COVID-19 Research Articles

P-1909. Social Connectedness in the COVID-19 Pandemic’s Aftermath: The Influence of Disease Status

Abstract Background During the COVID-19 pandemic, maintaining social connectedness became difficult.As the pandemic receded, these challenges eased and allowed people to re-develop their social relationships. However, those with Long COVID (LC) may experience ongoing difficulties given the effects of their illness, but limited research has examined the association of LC with social connectedness. Methods The US Census Bureau Household Pulse Survey data was used in this analysis. Data was collected online between January 9 - February 5, 2024, in English and Spanish. Sample size was N=68,544. Social connectedness metrics were compared between those reporting LC, COVID-19 infection that had resolved (Short COVID, or SC), and those who had not experienced COVID (No COVID, or NC). Data were analyzed using χ2 and between group contrast analysis. Results When asked how often they feel lonely, those with LC were significantly more likely to say always, usually, or sometimes as compared to SC and NC respondents and less likely to say rarely or never (all comparisons to LC p< .05). In terms of receiving necessary social and emotional support, only 21.6% of those with LC said they always get necessary support, vs. 30.9% for SC and 30.0% for NC (both LC comparisons p< .05). LC respondents were most likely to say they got together with friends or relatives less than once per week (47.1%, vs. 35.3% SC and 43.1% NC, all comparisons p< .05). Those experiencing SC were most likely to say they texted with friends, family or neighbors 5+ times per week (70.1%), followed by LC (65.1%), then NC (59.9%, all comparisons p< .05). Conclusion People suffering from LC generally exhibited lower levels of social connectedness and had lower likelihood of obtaining necessary social and emotional support than those who experienced SC or NC. Additional research should be conducted to better understand the causal connections: are people with poorer social connections more likely to experience LC, does LC damage the ability to become or remain socially connected, or both? More research is needed to examine these questions and develop programs to help rebuild and retain social connections in the aftermath of the COVID-19 pandemic. Disclosures All Authors: No reported disclosures

P-2132. Comparison of Clinical Characteristics and Risk Factors among Adult Patients with Bloodstream Infections due to candida auris vs other candida Species: a 3-year analysis in a Large Care Tertiary Hospital, Saudi Arabia

Abstract Background Candida auris is considered a serious global threat due to its potential to cause invasive infections, staggering transmissibility and mortality. We evaluated the epidemiologic and clinical features of candida bloodstream infections (BSIs) and explored risk factors associated with C. auris. Methods A retrospective review of all candida BSI in patients aged ≥ 18 years were conducted during August 2018 to June 2021. C. auris cases were compared to other Candida species cases. Odds ratio (OR), estimated using stepwise regression analysis, was used to assess the association between risk factors and incidence of C. auris infection. Results We identified 137 patients with first episode Candida BSIs. 32% patients were secondary to C. auris and the remaining were due to: C.albicans (20%), C.glabrata (18%), C.Parapsilosis (12%), C.trpicalis (15%), and others (4%). 60% of total cohort were male and their age were more than 55 yearsz. The proportions of patients with underlying diseases e.g. diabetes mellitus, hypertension, cardiovascular diseases, chronic renal diseases and COVID-19 infection were not significantly different. The prevalence of malignancy was significantly higher in non C. auris group (P= 0.01). The following risk factors were independently associated with C. auris BSI: Prior Use of antifungals (OR: 3.60, CI: 1.18-10.98), Previous history of multidrug resistant bacterial infection (OR: 3.37, CI: 1.41-8.06), and intensive care unit stay (OR 8.6, CI 2.61-28.37). Conclusion The epidemiology of candidemia is changing with non-albicans becoming predominant. Judicious use of all types of antimicrobials including antifungals will help in controlling the emergence of C. auris infection. Disclosures All Authors: No reported disclosures

Acute Macular Neuroretinopathy Following COVID-19 Infection: A Case Report

Acute Macular Neuroretinopathy Following COVID-19 Infection: A Case Report

Post COVID-19 infection and quality of life of healthcare workers at Sahloul University Hospital of Sousse in Tunisia.

Since the COVID-19 pandemic, health care workers (HCWs) faced an enormous physical and mental burden, sometimes altering their quality of life due mainly to persistent challenges stemming from their frontline position. Todetermine the prevalence of post-COVID-19 syndrome, and its impact on the Health-Related Quality of Life (HRQoL) among HCWs. This is an exhaustive cross-sectional study with analytical scope, conducted among all HCWs of the University Hospital Sahloul of Sousse, Tunisia, who have contracted COVID-19 between September 2020 and 30 March 2021 (N=529 cases).The post-covid medical check-up was carried out three months after the acute phase of the COVID-19 infection (December 2020 to June 2021). HRQoL was assessed using the SF-12 (12-item Short Form Health Survey) questionnaire. Bivariate study and multiple linear regressions were performed to identify the different factors influencing the quality of life of HCWs. During the study period, 529 HCWs were diagnosed with SARS CoV-2 infection, out of them 249 participants were included (47% participation rate). Post covid-19 syndrome was reported in 65% of cases. A low overall quality of life (QoL) score was reported in 28.6% of cases. Low physical and mental composite scores were reported in 34.3% and 29.4% of cases respectively. In the multiple linear regression analysis, gender, post COVID-19 syndrome and time off work were significantly associated with SF12 scores. In our study, HCWs experienced a significant deterioration in HRQoL after COVID-19 with a high incidence of post-COVID-19 syndrome. The need of long-term follow-up after SARS-CoV-2 infection remains essential to support HCWs and mitigate long-term impacts.

Self-Reported Long COVID and Its Impact on COVID-19-Related Worries and Behaviors After Lifting the COVID-19 Restrictions in China

Objective: Since the lifting of the COVID-19 restrictions in China in November 2022, there has been a notable surge in the COVID-19 infection rate. Little is known about the prevalence of long COVID among the general adult population and its impact on COVID-19-related worries and behaviors after the policy change. Methods: This cross-sectional study recruited 1530 adults with prior COVID-19 infection in Guangzhou from February to March 2023. Logistic regression analyses and trend analyses were performed to investigate the associations between long COVID- and COVID-19-related worries and preventive behaviors. Results: The estimated prevalence of long COVID among adults in China was 18.0% (95% confidence interval: 16.1% to 20.0%). Common long COVID symptoms included cough (60.7%), fatigue (47.6%), dyspnea (34.5%), palpitation (26.2%), and insomnia (25.1%). Adjusted for background variables, individuals with long COVID exhibited higher level of COVID-19-related worries compared to those who had fully recovered from the infection (reference: without long COVID; adjusted odds ratios ranged from 1.87 to 2.55, all p values < 0.001). Participants primarily expressed worries regarding the potential for COVID-19 reinfection, the impact of the pandemic on daily life, the increasing number of COVID-19 cases and deaths, and the capacity of the healthcare system. While long COVID did not statistically significantly affect their preventive behaviors. Conclusions: Long COVID was prevalent among the general adult population in China after lifting the COVID-19 restrictions, and it had a significant impact on COVID-19-related worries. This study highlights the importance of monitoring the mental health of individuals with long COVID and developing targeted intervention strategies to improve their adherence to preventive measures.

P-1988. COVID-19 vaccine induced antibodies in human milk: exploring form and function

Abstract Background Following SARS-CoV-2 vaccination/infection of pregnant/lactating women, human milk contains SARS-CoV-2 antibodies (Ab). Limited data exists on whether those Ab induce protection for infants against COVID-19. Among 45 lactating women who received primary and booster SARS-CoV-2 vaccines from 2021 to 2022, we previously showed that anti-receptor binding domain (RBD) IgG and IgA significantly increased in serum and milk following booster SARS-CoV-2 vaccine but did not differ by maternal nucleoprotein (NP) status. In this exploratory analysis, we aimed to further characterize the Ab present in human milk following maternal booster SARS-CoV-2 vaccination. SARS-CoV-2 Neutralization Antibodies in Human Milk by Maternal Nucleoprotein Status before and after SARS-CoV-2 Booster Vaccine. Neutralization titers in human milk significantly increased among women with hybrid immunity (NP+) after booster vaccine (P=0.04) but not for women with vaccine only immunity (NP-). Methods Using a subset of paired longitudinal milk and blood samples from a cohort of 45 lactating women who received primary and booster SARS-CoV-2 vaccines from 2021 to 2022, we characterized neutralizing Ab, RBD IgG subclasses (IgG1-IgG4), and Ab-dependent complement activation (ADCA). Antibody-Dependent Complement Activation (ADCA) using Human Milk from Lactating Women before and after SARS-CoV-2 Booster Vaccine. Two women with hybrid immunity (NP+) had significantly positive ADCA after SARS-CoV-2 booster vaccine, human milk from all others resulted in low or no activation of complement. Results For 7 NP+ (hybrid immune) and 7 NP- (vaccine immune) women, SARS-CoV-2 neutralization titers increased in serum and milk after booster vaccine among NP+ women (p=0.04) but not for NP- women (Fig1). After booster vaccine, ADCA was positive but variable in maternal serum and milk with only 2/12 (16%) women demonstrating high-levels of ADCA in human milk (Fig2). These same two women demonstrated different IgG subclass profiles in milk after booster vaccine with moderate to high levels of IgG1 and IgG3, and low levels of IgG4 (Fig3). This was inverse for all other women who demonstrated moderate to low levels of IgG1 and high titers of IgG4 in human milk. Notably, both women with high ADCA response were NP+ and vaccinated with primary SARS-CoV-2 vaccine more than 4 months post-partum, while all others received primary SARS-CoV-2 vaccine while pregnant or less than a month post-partum. IgG Subclasses in Human Milk before and after SARS-CoV-2 booster vaccine by Complement Activation Status Human milk with high complement activation demonstrated higher levels of IgG1 and IgG3 after booster vaccine compared to women with low complement activation. Conclusion The different Ab profile may indicate a tolerizing response that could be related to pregnancy at time of initial antigen exposure or from repeat SARS-CoV-2 vaccination and warrants future investigation (additional samples are under analysis). Nonetheless, human milk demonstrates robust binding and neutralizing Ab following SARS-CoV-2 vaccination, offering other potential mechanisms for protection of infants against COVID-19 infection. Disclosures Anne-Marie Rick, MD, MPH, PhD, Pfizer: Advisor/Consultant

P-1991. Unique Demographic Characteristics of Patients Experiencing Long COVID

Abstract Background As the COVID-19 pandemic retreats, health care providers now treat many patients experiencing lingering symptoms long after their initial infection, also known as Long COVID (LC). Given that the population of those affected by LC has been generally cumulative, understanding the current demographics of this population is critical to public health planning. Methods The US Census Bureau Household Pulse Survey data was used in this analysis. The survey data was collected January 9 - February 5, 2024. Respondents were asked about a variety of demographic factors, as well as their self-reported COVID-19 experiences. The survey was conducted online; N=68,544 respondents were included in the analysis. Demographic factors were compared between those reporting LC, COVID-19 infection that had resolved (Short COVID, or SC), and those who had not experienced COVID (No COVID, or NC). Data were analyzed using X2, between group contrast analysis, and non-parametric tests. Results Among those surveyed, 16.5% reported experiencing LC, 42.2% reported SC and 41.3% reported NC. Among those who reported LC, 64.3% identified as female (vs. 53.1% SC and 53.0% NC, comparisons to LC p< .05). The median incomes by group were LC $54.6k, SC $75.4K, and NC $59.2K (all pairwise comparisons p< .001). Median age for those with LC was 50 years old, SC was 52 years old, and NC was 60 years old (all pairwise comparisons p< .001). LC individuals were 10.1% Hispanic of any race, compared to SC 8.0% and NC 7.6% (comparisons to LC p< .05). Additionally, 6.3% of those with LC described themselves as Black or African American, vs. 5.7% of SC and 9.6% NC (comparisons to NC p< .05). Conclusion Patients experiencing LC have a substantially different demographic profile than both those who experienced SC and NC. LC individuals are younger, poorer, more female, and more likely to be Hispanic. The reasons for these differences are unclear and merit further study, but the general finding that people with LC are more likely to belong to marginalized groups suggests they could have greater difficulty getting adequate care. Reportedly, LC patients may feel their illness is trivialized by others, and these findings underscore the importance for medical personnel to identify and validate LC patient experiences. Disclosures All Authors: No reported disclosures

P-1403. Measuring Impact of COVID-19 Pandemic using Novel EPII Survey on PLWH in New Orleans

Abstract Background Research has shown that the impacts of the COVID-19 pandemic stretch beyond solely physical health. This study uses the newly developed Epidemic-Pandemic Impacts Inventory (EPII), a 92-item tool designed to quantify the impact of COVID-19 pandemic across several personal and social domains. People living with HIV (PLWH) have an increased morbidity and mortality associated with COVID-19 infection and are overall more vulnerable to social change. The current study uses the EPII to compare pandemic-related experiences of PLWH to those without HIV in New Orleans. Methods The Tulane University COVID-19 Antibody and Immunity Network (TUCAIN) maintains a longitudinal cohort of PLWH who provide clinical data and biological specimens for studies on the immune response to COVID-19 infection and vaccination. For the current study, participants were asked to complete the EPII assessing their perception of the pandemic. Participants were invited to complete the survey in person or via phone with a study coordinator. Responses from participants ≥18 years old who completed the survey were reviewed. Survey responses were analyzed using SPSS software. Results Both the PLWH (N=54) and control group (N=220) were similar in age; however, the PLWH subset was predominantly male and more racially diverse. PLWH reported more severe impacts of pandemic such as food insecurity (χ2=15.9; df=1; p< 0.01) and loss of employment (χ2=26.9; df=1; p< 0.01) and housing (χ2=6.6; df=1; p=0.01). PLWH reported more interruptions in medical care (χ2=12.6; df=1; p< 0.01) and more health problems unrelated to COVID-19 (χ2=7.2; df=1; p< 0.01). The PLWH subset was also less likely overall to report positive impacts of the pandemic (i.e. increased quality time with loved ones) compared to control group. Conclusion Results indicate that the HIV cohort reported greater rates of financial and health ramifications of the pandemic relative to control population. This study further reinforces the notion that this population was more susceptible to the socioeconomic turmoil of the COVID-19 pandemic. The results from this study will help to refine EPII as a survey tool for use in future pandemics and more precisely identify domains of social impact that affect the PLWH population the most. Disclosures All Authors: No reported disclosures

P-1987. Effectiveness of Tixagevimab-Cilgavimab as Pre-Exposure Prophylaxis in Patients Undergoing Hematopoietic Cell Transplant or Chimeric Antigen Receptor T-cell Therapy

Abstract Background Tixagevimab-cilgavimab (tixa-cil), was approved for emergency use authorization by the FDA in December of 2021 for pre-exposure prophylaxis of the COVID-19 virus in immunocompromised populations due to concerns about vaccine efficacy. Data regarding real world efficacy of tixa-cil in preventing SARS-CoV-2 infection in immunocompromised patients is limited.Table 1Patient Demographics Methods We conducted a retrospective analysis of all patients who had received hematopoietic cell transplantation (HCT) or chimeric antigen receptor T-cell (CAR-T cell) therapy between 12/1/2021-12/1/2022 at the University of North Carolina Bone Marrow Transplant and Cellular Therapy Program and were eligible to receive tixa-cil as pre-exposure prophylaxis. Patient demographics, underlying malignancy type, COVID-19 vaccine status, data and number of tixa-cil injections, cellular infusion type, presence of GVHD, adverse events, and cause of death if related to COVID-19 were all collected.Table 2Therapeutic Agents Used For Treatment of COVID-19 Results Of 184 eligible patients, 113 (61%) received at least one tixa-cil injection. Forty-five cases of either documented or reported COVID-19 infection following cell infusion (including 8 recurrent infections) were identified. Of the 113 patients who received tixa-cil, 14 (12%) had a documented positive COVID test within 6 months. In comparison, 23 (32%) of the 71 patients who did not receive tixa-cel had a documented positive COVID test, (p=0.0013, Fisher’s exact test), OR=0.2951. Of 13 COVID-related hospitalizations, only one occurred in a patient who received tixa-cil, (p=0.0048, Fisher’s exact), OR=0.0641. Number of Patients with Documented COVID Infections Who Did and Did Not Receive Tixa-Cil Conclusion Our findings indicate that tixa-cil was effective as pre-exposure prophylaxis in reducing SARS-CoV-2 infection and disease severity in a highly immunocompromised patient population. While the FDA removed authorization for ongoing use of tixa-cil in January 2023 due to its ineffectiveness against the Omicron variants, our data suggest that mAbs are highly effective in providing protective passive immunity to patients at risk of impaired vaccination responses. Pemibivart, a new anti-SARS-CoV-2 spike protein mAb, was recently authorized by the FDA. Our results suggest a clinical benefit for this therapy; however, real world studies will be needed to determine actual efficacy. Number of Patients Hospitalized Related to COVID Infection Who Did and Did Not Receive Tixa-Cil Disclosures Jonathan Ptachcinski, PharmD, Johnson & Johnson: Company Employee

P-1999. Predictors of Mortality in Myelodysplastic Syndrome with COVID-19: A 2020-2021 National Study

Abstract Background We aimed to evaluate mortality predictors in Myelodysplastic Syndrome who were admitted for COVID-19 (MDSCov) using the Healthcare Cost and Utilization Project. Sociodemographics in MDSCoV Patients Methods A cross-sectional study using the NIS on adults (≥ 18 years) hospitalized in the United States for MDSCov (n=769). We identified 151 nonsurvivors among MDSCov. Analysis was done using t-tests and chi-square tests, and multivariate regression models were constructed with p≤ 0.05 significance. Factors Associated with Higher Mortality in MDSCoV Patients Results The average age of MDSCov was higher than those without COVID-19 (77.3 vs 53.5 years, p=0.0000). MDSCov had a longer average length of stay (7.9 vs 5.1 days, p=0.0000) and higher total hospital charges ($85,059.6 vs $66887.8, p=0.0001) compared to MDS patients without COVID-19. We found that HSCT (allogenic and autogenic) was not associated with increased MDSCov hospitalization (2.2% vs 2.5%, p=0.8286). Males experienced a higher mortality rate (64.9% vs 53.9%, p=0.015; aOR 1.51, p=0.076) as they have higher expression of ACE2 receptors than females, correlating to disease severity. Race did not contribute to mortality (White 72.8% vs 77.3%, p=0.5267). The Non Survivors of MDSCov showed a high association with stroke (2% vs 0.3%, p=0.0227; aOR 4.7, p=0.026), severe sepsis (17.9% vs 0.6%, 0.0000; 9.1, 0.000), acute respiratory failure (66.9% vs 49.5%, 0.0001; 3.93, 0.000), and acute kidney injury (45.7% vs 29.1%, 0.0001; 1.27, 0.326). Due to COVID-19, T-cell exhaustion and secondary infections that contribute to sepsis can occur. Increased microthrombus formation and endothelial dysfunction can lead to thromboembolic episodes. Increased proinflammatory cytokines (IL-1β, IL-6, IL-12, IFN-γ, IP-10, and MCP-1) caused by the virus contribute to pulmonary inflammation and lung injury. The use of vasopressors to maintain MAP (9.3% vs 0.2%, p=0.0000; aOR 6.65, p=0.081) was markedly higher but not significant among nonsurvivors. Sociodemographic Profile of Patients with MDS Conclusion Our study identified several predictors of mortality in MDSCov. However, due to the need for more information on disease severity and laboratory evidence, future studies are needed to develop timely treatment plans. Appropriate chemotherapeutic regimens for MDS and antivirals/biologics for COVID-19 are needed. Predictors of In-hospital Mortality in Patients with MDS and COVID-19 Disclosures All Authors: No reported disclosures

P-2039. Prognostic factors of disease progression in patients with mild-to-moderate COVID-19 on early remdesivir treatment in Taiwan

Abstract Background An early 3-day course of remdesivir treatment was recommended for high risk patients with mild-to-moderate COVID-19. We investigated the prognostic factors of disease progression and mortality in patients with mild-to-moderate COVID-19 who were treated with a 3-day course of remdesivir in Taiwan. Methods Adult patients with mild-to-moderate COVID-19 treated with a 3-day course of remdesivir at Taipei Veterans General Hospital from April–July 2022 were identified. The main outcomes were 14-day disease progression (defined as increased oxygen requirement compared with the baseline condition or mortality) and 28-day mortality. Logistic regression was used to identify independent variables associated with poor outcomes. Results Among the 345 patients on early remdesivir treatment with a 3-day course, 62 patients (18%) had 14-day disease progression, and 5 patients (1.4%) died within 28 days. Eighty patients (23.2%) did not receive COVID-19 vaccine before the diagnosis of COVID-19. Body mass index, cardiovascular disease, Charlson Comorbidity Index, and secondary bacterial infection were independent factors associated with 14-day disease progression, and nosocomial COVID-19 was the only independent factor associated with 28-day mortality. In 233 patients (67.5%) administered at least two doses of COVID-19 vaccine, 38 patients (16.3%) had 14-day disease progression, and 4 patients (1.7%) died within 28 days. Female sex, cardiovascular disease, and secondary bacterial infection were independent factors for 14-day disease progression. Nosocomial COVID-19 and C-reactive protein levels >10 mg/dL were independent factors associated with 28-day mortality. Conclusion Nosocomial COVID-19 and secondary bacterial infections predisposed these patients to poor outcomes, regardless of vaccination. Therefore, infection control measures are important in the fight against COVID-19. Disclosures All Authors: No reported disclosures

P-1596. Procalcitonin: A Promising Tool in Post COVID-19 Antibiotic Prescribing at a Community Teaching Hospital

Abstract Background A rise in antibiotic use was universally observed during the COVID-19 pandemic. Use of procalcitonin (PCT) in understanding the bacterial burden of disease both in the context of COVID-19 and other infections continues to be associated with much debate. Our hospital saw a precipitous rise in antimicrobial use during COVID-19, despite ongoing efforts of antimicrobial stewardship. We looked to PCT to help curb antibiotic overprescribing following the COVID-19 pandemic. Hospital wide SAAR Methods This was a single-center, before and after study to evaluate the impact of PCT implementation at a 500-bed community teaching hospital on antimicrobial usage. Education was provided to all providers before and during PCT implementation. A lab order was added to the existing sepsis clinical pathway and a pocket card detailing the appropriate use of PCT for approved indications (lower respiratory tract infections and sepsis) was provided to clinicians. For the primary outcome, we evaluated the standardized antimicrobial administration ratio (SAAR) before and after PCT implementation. Secondary outcomes included antibiotic consumption as described by days of therapy (DOT) per 1000 days present (DP), change in antimicrobial cost, appropriateness of testing and adherence to the PCT prescribing algorithm included in the pocket guide. ICU SAAR Results Since becoming available at our hospital, PCT has been ordered on average 583 times per month. On average, monthly SAARs were 8.4% lower during post-PCT period (1.06 vs 0.98; p=0.0011) (Figure 1). A decline was observed in both intensive care units (ICU) as well as non-ICU inpatient wards (Figure 2, 3). Total antimicrobial utilization decreased by 8.5% (550 vs 503 DOT/1000 DP), which translated to a 19.3% reduction in antimicrobial spending. Appropriateness of the initial PCT testing was 74% and appropriate discontinuation of antibiotics based on PCT algorithm was 80% during 18-months of PCT use. Non-ICU SAAR Conclusion Our findings suggest that appropriate use of PCT added to antimicrobial stewardship can be a valuable tool in both ICU and non-ICU settings. Disclosures Elizabeth Nothdurft, PharmD, BCPS, BCIDP, Abbvie: Honoraria Nirmol Philip, MD, MPH, Nestle: Honoraria

P-1421. A socioeconomic index of Brazilian municipalities correlates with dengue cases severity status but not with lethality

Abstract Background Social determinants of health (SDOH) affect a wide range of health outcomes and risks. This includes differences in exposure and vulnerability to infectious diseases such as tuberculosis, COVID-19 and arboviral diseases. However, information on SDOH can be difficult to retrieve from medical records. We set out to explore how SDOH measured at populational level can affect natural history and lethality in dengue fever. ORs from logistic regressions performed Methods We performed a retrospective, descriptive study of dengue fever cases in Brazil, using Ministry of Health openly available notification databases. We used GeoSES, a composite index that summarizes the main dimensions of the Brazilian socioeconomic context for research purposes, as a proxy for SDOH in given municipalities. Only laboratory confirmed cases were included. Outcomes considered were case classification (dengue without warning signs, dengue with warning signs or dengue with severity signs) and discharge or death by dengue. We performed logistic regressions of recognized risk factors alongside GeoSES as predictors for outcomes. R software version 4.3.1 was used for analysis. Code will be made public upon abstract acceptance. Results We analyzed 2,137,462 cases notified between January 2014 and December 2023. In the proportional odds logistic regression model for case classification, the GeoSES index was associated with case classification (OR = 2.87, 95% CI 2.77-2.98; p-value < 0.0001), indicating an increased risk of dengue with warning signs or severity signs as the index increases. However, in the binomial logistic regression for discharge or death, the index showed no association (OR = 0.99, 95% CI 0.88-1.12; p-value = 0.98) with outcome, holding constant all other variables. Interestingly, peptic ulcer disease stood out as a protective factor against negative outcomes in dengue fever patients. Conclusion As a seasonal disease with a recent upsurge in Brazil, reevaluating risk factors for dengue infection and complication is an ever-present necessity. Here, we demonstrate that the GeoSES index is not a strong predictor of dengue fever mortality. This does not excuse policymakers from improving structural conditions, but allows for rational evaluation in epidemic scenarioes. Disclosures All Authors: No reported disclosures

P-2072. COVID-19 and RSV Prevention Products in Pregnancy – Overcoming COVID-19 Network, United States, October 2023–March 2024

Abstract Background Maternal vaccines for COVID-19 and respiratory syncytial virus (RSV) are tools to prevent severe infant respiratory disease. Among recently pregnant people with hospitalized infants < 6 months with COVID-19 or COVID-like illness, we evaluated receipt of these products and association with provider recommendations, other vaccine receipt, and acceptability of future vaccines in pregnancy. Methods Mothers of infants < 6 months hospitalized either for COVID-19 or COVID-like illness were interviewed for the Overcoming COVID-19 Network. Outcomes were 1) verified receipt of COVID-19 and maternal report of RSV vaccines during pregnancy by provider recommendation (among those eligible for updated/new vaccine based on date of vaccine approval and infant date of birth), 2) influenza and Tdap vaccine receipt during pregnancy, and 3) willingness to receive vaccines in future pregnancies. Results Caregivers of 514 (68%) of 760 hospitalized infants < 6 months were interviewed; 216 (42%) of 514 interviews were among mothers. Seven (5%) of 147 eligible mothers received COVID-19 vaccine during pregnancy, 8 (5%) were vaccinated 1 to 180 days before pregnancy, and 132 (90%) were vaccinated >180 days before pregnancy or not at all. Ten (9%) of 113 eligible mothers received the RSV vaccine during pregnancy; 20 (19%) mothers who did not receive RSV vaccine reported their infant receiving an infant monoclonal antibody against RSV. Provider recommendation was associated with maternal receipt of both COVID-19 and RSV vaccines during pregnancy (Figure 1A, 1B). Tdap was the most received vaccine during pregnancy (n=117 [61%]) (Figure 2). Willingness to receive vaccines in a future pregnancy was common for Tdap (n=93, 58%), influenza (n=88, 55%), and RSV (n=87, 54%). Only 22% (n=35) of mothers stated they would be willing to receive a COVID-19 vaccine in a future pregnancy. Conclusion Among mothers of infants hospitalized with COVID-19 or COVID-19-like illness, few had received a COVID-19 vaccine during or within 180 days before pregnancy. Tdap and influenza vaccines were more commonly received during pregnancy and were more acceptable in future pregnancies. Provider recommendation was associated with receipt of COVID-19 and RSV vaccines during pregnancy. Disclosures Regina Simeone, PhD, Pfizer: Stocks/Bonds (Private Company) Adrienne G. Randolph, MD, MSc, Illumina, Inc.: Reagents|Inotrem: Advisor/Consultant|Thermo Fisher, Inc.: Advisor/Consultant

P-1995. A Nationwide Cohort Study of Delta and Omicron SARS-CoV-2 Outcomes and Vaccine Effectiveness amongst Individuals with Chronic Heart Failure or Ischemic Heart Disease

Abstract Background Individuals with heart failure (HF) / ischemic heart disease (IHD) have poorer outcomes following respiratory viral infections; however, data is lacking on outcomes and Vaccine Effectiveness (VEs) following SARS-CoV-2 infection with newer COVID variants. Methods Outcomes of Delta/Omicron SARS-CoV-2 infection in a highly vaccinated/boosted cohort of adult Singaporeans with HF/IHD were contrasted against matched population controls. Matching was conducted based on age, sex, ethnicity, socioeconomic status, and comorbidities. Cox regressions were used to compare risk of infection, COVID-19-related hospitalisations and severe COVID-19 disease and estimate VEs. Results 15,426 HF patients and 110,442 IHD patients were matched to 41,221 and 223,843 population controls, respectively. Compared with controls, higher risk of COVID-19 hospitalisation and severe disease was observed amongst HF cases during Delta (hospitalisation: adjusted-hazards-ratio, aHR=1.40[1.20-1.62]; severe-COVID-19: aHR=1.66[1.28-2.14]) and Omicron (hospitalisation: aHR=1.77[1.65-1.90]; severe-COVID-19: aHR=2.40[2.10-2.75]). Higher risks were also observed for infected IHD patients, albeit to a smaller extent (Omicron, hospitalization: aHR=1.21[1.17-1.26]; severe-COVID-19: aHR=1.12[1.03-1.21]). During both Delta and Omicron waves, the risk of COVID-19-related infection, hospitalisation and severe disease was significantly lower in boosted groups compared against those who had only received 2 doses. VEs were comparable with controls for IHD, with lower effectiveness observed against hospitalisation amongst HF patients (3 doses aHR=0.42[0.37-0.48]; 4 doses aHR=0.28[0.23-0.34]) compared to controls (3 doses: aHR=0.28[0.23-0.34]; 4 doses: aHR=0.18[0.16-0.22]). Conclusion Higher risks of severe COVID and comparable VEs suggest that it is more cost effective to boost IHD/HF patients. Lower VEs amongst HF patients point to the need for more boosters to achieve similar rates of protection. Disclosures All Authors: No reported disclosures

P-2035. Pharmacokinetics (PK) and Serum Virus Neutralizing Antibody (sVNA) Titers Following the 2nd dose of Pemivibart in the Phase 3 CANOPY Trial

Abstract Background Pemivibart (PEM) is a half-life extended recombinant human monoclonal IgG1 antibody that targets the SARS-CoV-2 spike protein receptor binding domain. PEM has been granted emergency use authorization (EUA) for the pre-exposure prophylaxis of COVID-19 in certain adults and adolescents with moderate-to-severe immune compromise, with dosing recommended every 3 months. Methods CANOPY (NCT06039449) is a Phase 3 study investigating PEM 4500 mg for the prevention of COVID-19 that enrolled adult (≥18 years) participants (ppts) with immune compromise (Cohort A, single arm, open label) and those at risk of exposure to SARS-CoV-2 (Cohort B, randomized 2:1 to PEM or placebo). Ppts received an initial dose of study drug administered via intravenous (IV) infusion on Day 1 followed by a second dose approximately 3 months later (i.e., month 3). Serum samples were collected for PK analysis at the month 3 visit prior to and after receipt of the second PEM dose and at month 6 and month 12. Here we describe calculated sVNA titers for ppts in Cohort A following a second dose of PEM and further estimates from a population PK (PPK) model constructed with available data from a Phase 1 first-in-human study and the Phase 3 CANOPY study. Results At the completion of the second (i.e., month 3) dose of PEM, the calculated sVNA geometric mean titer (GMT) to the SARS-CoV-2 Omicron JN.1 variant in Cohort A ppts was 17% higher than the corresponding value following the initial PEM dose. This is consistent with the estimated accumulation ratio based on the PPK model. Based on this model, the median calculated GMT is predicted to remain above the predefined protection titer threshold of 3514 for at least 90 days following dosing at month 3 (Figure 1). The steady-state AUC over the entire 3-month dosing interval is estimated to be approximately 30% higher than the AUC observed following the initial dose. Conclusion A second dose of PEM 4500 mg IV given at month 3 boosted calculated sVNA titers and is anticipated to provide continued protection above predefined protection titer thresholds in immune compromised participants through 90 days post-dose for JN.1. The overall risk-benefit of PEM supports use in certain adults and adolescents with moderate-to-severe immune compromise for the prevention of COVID-19 per the EUA. Disclosures Anna Holmes, PhD, Invivyd, Inc.: employee|Invivyd, Inc.: Stocks/Bonds (Private Company) Yong Li, PhD, Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Deepali Gupta, BSc, Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Chloe Katz, PMP, Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Mike Gavazzi, B.S., Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Pamela Hawn, Pharm.D., Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Kathryn Mahoney, PharmD, Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Myra Popejoy, Pharm.D., Invivyd, Inc.: employee|Invivyd, Inc.: Stocks/Bonds (Public Company)

91. Clinical Efficacy Endpoints from the Phase 3 CANOPY Study Evaluating Pemivibart

Abstract Background Pemivibart (PEM) is a half-life extended recombinant human monoclonal IgG1 antibody that targets the SARS-CoV-2 spike protein receptor binding domain. PEM has been granted emergency use authorization (EUA) for the pre-exposure prophylaxis of COVID-19 in certain adults and adolescents with moderate-to-severe immune compromise. Methods CANOPY (NCT06039449) is a Phase 3 study investigating the prevention of COVID-19 in immunocompromised participants (ppts) (Cohort A; single arm, open label) and in ppts at risk of exposure to SARS-CoV-2 (Cohort B; randomized 2:1 PEM 4500 mg or placebo). Ppts received an initial dose of study drug administered via intravenous (IV) infusion on Day 1 followed by a second dose of study drug approximately 3 months later. The safety, tolerability, pharmacokinetics (PK), immunogenicity, and clinical efficacy of PEM is being evaluated. Here we describe an exploratory endpoint of reverse transcription polymerase chain reaction (RT-PCR)-confirmed symptomatic COVID-19 that developed within 90 days following the first administration of either PEM or placebo among ppts without SARS-CoV-2 infection at baseline. Nasopharyngeal and saliva samples were collected for central SARS-CoV-2 testing by RT-PCR and subsequent whole genome sequencing (WGS). Results RT-PCR-confirmed COVID-19 cases were observed in 3 of 298 ppts (1%) with significant immune compromise who received a full initial dose of PEM in Cohort A and 9 of 484 (1.9%) ppts who received either PEM or placebo in Cohort B. In Cohort B, RT-PCR confirmed COVID-19 cases were observed in 1 (0.3%) PEM-treated ppt compared to 8 (5.0%) placebo-treated ppts (Absolute Risk Reduction: -4.73% (95% CI: -8.2, -1.3), nominal p = 0.0070). Characteristics of these cases are described in Table 1. All but one COVID-19 case were self-reported as mild or moderate in severity. SARS-CoV-2 variants including JN.1, EG.5.1, and other related lineages were identified. Conclusion This exploratory analysis of COVID-19 events demonstrated a clinically meaningful reduction in COVID-19 with PEM treatment versus placebo. Disclosures Myra Popejoy, Pharm.D., Invivyd, Inc.: employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Anna Holmes, PhD, Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Chloe Katz, PMP, Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Anne-Marie Phelan, MA, Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Kazima Tosh, Ph.D., Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Yong Li, PhD, Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Deepali Gupta, BSc, Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Pamela Hawn, Pharm.D., Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Kristin Narayan, Ph.D., Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Kathryn Mahoney, PharmD, Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company) Mark Wingertzahn, Ph.D., Invivyd, Inc.: Employee|Invivyd, Inc.: Stocks/Bonds (Public Company)

426. Effectiveness of Updated (2023-2024) Monovalent COVID-19 Vaccines – VISION Network, September 2023-March 2024

Abstract Background In September 2023, the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP) recommended updated 2023-2024 (monovalent XBB.1.5) COVID-19 vaccines for use in persons ≥6 months for prevention of COVID-19, including severe disease. Understanding how well updated COVID-19 vaccines work in the context of high population immunity due to prior infection, vaccination, or both, is important for future vaccine policy decisions, as well as informing patient/provider discussions, and increasing vaccine confidence. Effectiveness of updated (2023-2024) COVID-19 vaccination against laboratory-confirmed COVID-19-associated emergency department/urgent care encounters and hospitalization among immunocompetent adults aged ≥18 years — VISION Network, September 2023–March 2024 Methods VISION, an electronic health record (EHR)-based network including emergency departments/urgent care clinics (ED/UCs) and hospitals including 6 health systems, uses clinician-ordered testing data to estimate vaccine effectiveness (VE) for respiratory viruses. COVID-19 VE was estimated using the test-negative design, comparing the odds of vaccination with a single updated 2023-2024 COVID-19 vaccine dose between patients who tested positive versus those who tested negative for SARS-CoV-2 by molecular assay, adjusting for potential confounders. Effectiveness of updated 2023–2024 (monovalent XBB.1.5) COVID-19 vaccination against laboratory-confirmed COVID-19–associated hospitalization among immunocompromised adults aged ≥18 years — VISION network, September 2023–March 2024 Results A total of 198,345 ED/UC encounters and 59,777 hospitalizations between September 2023-March 2024 among immunocompetent adults ≥18 years with symptoms of COVID-19 were included. VE against COVID-19-associated ED/UC encounters comparing receipt of an updated dose to no receipt of an updated dose was 50% (95% CI: 46-53%) in the 7-59 days and 0 (95% CI: -14 to 12) in the 120-179 days after receipt of an updated dose (Table 1). VE against COVID-19-associated hospitalization was 50% (95% CI: 44-56%) in the 7-59 days and 23 (95% CI: 2-39) in the 120-179 days after receipt of an updated dose (Table 1). A total of 17,417 hospitalizations among immunocompromised adults ≥18 years with symptoms of COVID-19 were included, with a VE of 38% (95% CI: 23-50%) in the 7-59 days and 14 (95% CI: -33 to 44) in the 120-179 days after receipt of an updated dose after an updated dose (Table 2). Conclusion Receipt of an updated COVID-19 vaccine dose provided protection against COVID-19-associated ED/UC encounters and hospitalizations among immunocompetent and immunocompromised adults, although waning was evident. Disclosures Nicola P. Klein, MD, PhD, GlaxoSmithKline: Grant/Research Support|Merck: Grant/Research Support|Pfizer: Grant/Research Support|Sanofi Pasteur: Grant/Research Support|Seqirus: Grant/Research Support Toan Ong, PhD, Patent Title: Systems and Methods For Record Linkage: PCT/US2018/047961 Patent Title: Systems and Methods For Record Linkage|PCORI: Travel support to attend the PCORI Annual meeting in Washington DC, 2023|Regenstrief Institute: Advisor/Consultant|Regenstrief Institute: Travel support to attend the OHIE 23 meeting in Malawi. Brian E. Dixon, PhD, Elsevier: Honoraria

P-1931. Health-related quality of life one year after mild COVID-19 infection: a multicenter prospective cohort study

P-1931. Health-related quality of life one year after mild COVID-19 infection: a multicenter prospective cohort study

P-2066. Impact of XXB 1.5 Monovalent Booster Vaccination on Mucosal and Systemic Immune Responses in Healthy Adults

Abstract Background The FDA recently approved the first monovalent XBB1.5 booster vaccine. However, the mechanism by which this vaccine stimulates mucosal and systemic immune responses has been understudied.Figure 1.Impact of XBB 1.5 vaccination on viral neutralization titers using pseudo virus assay (left panel) and ACE2 inhibition assay (right panel).Each dot (white) represents a single serum sample tested in parallel with a post-vaccination sample (colored dot) for each of the 28 participants. The mean fold increase in neutralization titers pre- and post-vaccination are shown for Wuhan, XBB 1.5, and BA5 variants. All increases in neutralization titers are significant to P<0.0001 by employing Wilcoxon matched-pairs signed rank test. Methods We examined 28 participants' serum and saliva one week before and two to three weeks after the XBB1.5 mRNA vaccination for neutralizing and binding antibodies to Wuhan and XBB1.5 S protein.Figure 2:Inhibition of ACE2 binding to different S variants by saliva samples pre- and post-vaccination with XBB1.5 monovalent booster.Paired samples represent the percent ACE2 binding inhibition in participants before and after vaccination. Vaccination induced a 1.7-fold increase in ACE2 neutralization in saliva to XBB1.5 (p<0.0001) and 1.2-fold increase in ACE2 neutralization to Wuhan (p=0.03). Significance tested between pre and post-vaccination by Wilcoxon matched-paired sign rank test. *** p<0.001, **** p<0.0001. Results We observed a 2.9 to 2.6-fold and 5.0 to 7.8-fold increase in Wuhan and XBB1.5 serum neutralization titers following mRNA vaccination using pseudovirus and ACE2 neutralization assays respectively, that closely correlated with a rise in binding antibodies to S protein. Vaccination induced a 1.7-fold increase in ACE2 neutralization in saliva to XBB1.5 (p< 0.0001) and 1.2-fold increase in ACE2 neutralization to Wuhan (p=0.03). This increase in neutralization Ab levels in saliva failed to correlate with the number and time of prior COVID-19 infections, vaccination status, type of vaccine, or concomitant rise in S-specific IgA or IgG in saliva or serum. Depletion of IgA or IgG in saliva following vaccination demonstrated that IgA was primarily responsible for the increase in ACE2 blocking activity (mean reduction in blocking activity with IgA depletion=68%, range, 58-81%) compared to IgG (mean reduction=27%, range 0-71%).Figure 3.Role of IgA on percent reduction in ACE2 inhibition in saliva. Depletion of IgA or IgG in saliva following vaccination demonstrated that IgA was primarily responsible for the increase in ACE2 blocking activity (mean reduction in blocking activity with IgA depletion=68%, range, 58-81%) compared to IgG (mean reduction=27%, range 0-71%). Statistical analysis done using unpaired t test. Conclusion The XBB1.5 monovalent vaccine boosts systemic and mucosal viral neutralization antibody levels, primarily to the XBB1.5 variant. Most people have hybrid immunity to SARS-CoV2 now, so mRNA vaccines boost mucosal immune response better than observed earlier in the pandemic. Increased oral mucosal immunity may reduce the risk of COVID-19 progressing to pneumonia and more severe disease. Disclosures All Authors: No reported disclosures