Anti-nucleocapsid Antibodies Research Articles

Protection from Omicron Infection in Residents of Nursing and Retirement Homes in Ontario, Canada.

To identify factors that contribute to protection from infection with the Omicron variant of SARS-CoV-2 in older adults in nursing and retirement homes. Longitudinal cohort study with retrospective analysis of infection risk. 997 residents of nursing and retirement homes from Ontario, Canada, in the COVID in LTC study. Residents with 3 messenger RNA (mRNA) dose vaccinations were included in the study. SARS-CoV-2 infection was determined by positive nasopharyngeal polymerase chain reaction test and/or circulating antinucleocapsid IgG antibodies. Cumulative probability of Omicron infection after recent COVID-19 was assessed by log-rank test of Kaplan-Meier curves. Cox regression was used to assess risk of Omicron infection by age, sex, mRNA vaccine combination, whether individuals received a fourth dose, as well as recent COVID-19. In total, 171 residents (17.2%) had a presumed Omicron variant SARS-CoV-2 infection between December 15, 2021 (local start of the first Omicron wave) and May 3, 2022. Risk of Omicron infection was not different by age [hazard ratio (95% confidence interval) 1.01 (0.99‒1.02)], or in women compared with men [0.97 (0.70‒1.34)], but infection risk decreased 47% with 3 vaccine doses of mRNA-1273 (Moderna) compared with BNT162b2 (Pfizer) [0.53 (0.31-0.90)], 81% with any fourth mRNA vaccine dose [0.19 (0.12‒0.30)], and 48% with SARS-CoV-2 infection in the 3months prior to beginning of the Omicron wave [0.52, (0.27‒0.99)]. Vaccine type (ie, mRNA-1273/Spikevax vs BNT162b2/Cominarty), any fourth vaccine dose, and hybrid immunity from recent COVID-19, were protective against infection with the Omicron variant. These data emphasize the importance of vaccine type, and number of vaccine doses, in maintenance of protective immunity and reduction of risk of Omicron variant breakthrough infection. These findings promote continued public health efforts to support vaccination programs and monitor vaccine immunogenicity in older adults.

Immunogenicity and safety of mixed COVID-19 vaccine regimens in patients with immune-mediated inflammatory diseases: a single-centre prospective cohort study

ObjectiveAmong persons with immune-mediated inflammatory diseases (IMIDs) who received SARS-CoV-2 vaccines, we compared postvaccine antibody responses and IMID disease activity/states.DesignSingle-centre prospective cohort study.SettingSpecialty ambulatory clinics in central Canada.ParticipantsPeople with inflammatory...

Antibody titer after administration of mRNA-based vaccine against severe acute respiratory syndrome coronavirus 2 in liver transplant recipients.

The mRNA-based vaccine was released as a COVID-19 prophylactic; however, its efficacy in organ transplant recipients is unknown. This study aimed to clarify this in liver transplant recipients. Herein, liver transplant recipients from two hospitals who received vaccines were included. Immunoglobulin-G antibodies against the spike and nucleocapsid proteins were measured chronologically after the second, third, and fourth vaccine doses. Antibody levels in 125 liver transplant recipients and 20 healthy volunteers were analyzed. The median age at transplant was 35 (interquartile range 1, 53) years, and the period between transplant and the first dose was 15.2 ± 7.7 years. After the second and third doses, 89.1% and 100% of recipients displayed a positive humoral response, respectively. Anti-spike antibodies after the second dose were significantly reduced at 3 and 6 months, compared to that at 1 month (26.0 [5.4, 59.5], 14.7 [6.5, 31.4] vs. 59.7 [18.3, 164.0] AU/mL, respectively, p < 0.0001). However, a booster vaccine significantly elevated anti-spike antibodies in LT recipients (p < 0.0001) as well as in healthy controls (p < 0.0001). Additionally, the decay rate was comparable between the transplant recipients and controls (2.1 [0.8, 4.5] vs. 2.7 [1.1, 4.1] AU/mL/day, p = 0.9359). Only 4.0% of vaccinated transplant recipients were positive for anti-nucleocapsid antibodies. Liver transplant recipients can acquire immunity similar to that of healthy people through vaccination against SARS-CoV-2. The antibody decay rate is the same, and booster vaccinations should be administered similarly to that in healthy individuals.

Mid-term follow-up after COVID-19 vaccination in adults with CHD: a prospective study.

Long-term data on COVID-19 vaccine safety, immunogenicity, and acceptance in adults with CHD are lacking. This is a prospective study including adults with CHD patients undergoing COVID-19 vaccination from January 2021 to June 2022. Data on adverse events, antispike IgG titre, previous or subsequent COVID-19 infection, booster doses, and patients' attitude towards vaccination were collected. Four hundred and ninety CHD patients (36 ± 13 years, 53% male, 94% with moderate/complex defects) were prospectively included: 433 (88%) received a Pfizer-BioNTech mRNA vaccine, 31 (6%) Moderna mRNA vaccine, 23 (5%) AstraZeneca-Oxford ChAdOx1 nCov-19 vaccine, and 3 (0.6%) Janssen Vaccine; 310 (63%) received a booster dose. Median follow-up after vaccination was 1.53 [1.41-1.58] years. No major adverse event was reported. Eighty-two fully vaccinated patients contracted COVID-19 during follow-up after a median of 5.4 [4.3-6.5] months from the last dose. One patient with Ebstein's disease died from severe COVID-19. Symptoms' duration in patients who tested positive after vaccination was significantly shorter than in the group tested positive before vaccination (5.5 [3-8] versus 9 [2.2-15] days, p = 0.04). Median antispike IgG titre measured in 280 individuals (57%) at a median of 1.4 [0.7-3.3] months from the last dose was 2381 [901-8307] BAU/ml. Sixty patients (12%) also showed positive antinucleocapsid antibodies, demonstrating previous SARS-COV2 exposure. Twenty-nine percent appeared to have concerns regarding vaccine safety and 42% reported fearing potential effects of the vaccine on their cardiac disease before discussing with their CHD cardiologist. COVID-19 vaccines appear safe in the mid-term follow-up in adults with CHD with satisfactory immunogenicity and reduction of symptoms' duration in case of infection.

COVID-19としての入院診療中に，日本紅斑熱と診断し救命し得た1例

COVID-19 is manifested by various symptoms and needs to be distinguished from other diseases. We report the case of a patient with Japanese spotted fever (JSF) who was admitted with a diagnosis of COVID-19. The patient was a 72-year-old woman with high fever whose SARS-CoV-2 rapid antigen test was positive. She also had rashes on her trunk and extremities, including on her palms and soles. We treated her as a COVID-19 patient, viewing her rashes as a complication of COVID-19 or a drug eruption. However, her fever and rashes persisted. Her medical history revealed a history of mowing, which involves a high risk of tick bites, and we discovered an eschar on her left popliteal fossa. We then suspected JSF and treated her with intravenous minocycline and levofloxacin as a severe case. PCR testing of specimens from the eschar was positive for Rickettsia japonica. A confirmatory SARS-CoV-2 PCR test and an anti-nucleocapsid antibody test were negative. We ultimately diagnosed the patient with JSF, not COVID-19. The number of JSF patients in Japan has increased in recent years. Since the clinical presentation of JSF patients and COVID-19 patients is similar, a careful medical history and physical examination are necessary to make the differential diagnosis.

Estimated COVID-19 vaccine effectiveness against seroconversion from SARS-CoV-2 Infection, March–October, 2021

BackgroundMonitoring the effectiveness of COVID-19 vaccines against SARS-CoV-2 infections remains important to inform public health responses. Estimation of vaccine effectiveness (VE) against serological evidence of SARS-CoV-2 infection might provide an alternative measure of the benefit of vaccination against infection. MethodsWe estimated mRNA COVID-19 vaccine effectiveness (VE) against development of SARS-CoV-2 anti-nucleocapsid antibodies in March–October 2021, during which the Delta variant became predominant. Participants were enrolled from four participating healthcare systems in the United States, and completed electronic surveys that included vaccination history. Dried blood spot specimens collected on a monthly basis were analyzed for anti-spike antibodies, and, if positive, anti-nucleocapsid antibodies. We used detection of new anti-nucleocapsid antibodies to indicate SARS-CoV-2 infection, and estimated VE by comparing 154 case-participants with new detection of anti-nucleocapsid antibodies to 1,540 seronegative control-participants matched by calendar period. Using conditional logistic regression, we estimated VE ≥ 14 days after the 2nd dose of an mRNA vaccine compared with no receipt of a COVID-19 vaccine dose, adjusting for age group, healthcare worker occupation, urban/suburban/rural residence, healthcare system region, and reported contact with a person testing positive for SARS-CoV-2. ResultsAmong individuals who completed a primary series, estimated VE against seroconversion from SARS-CoV-2 infection was 88.8% (95% confidence interval [CI], 79.6%–93.9%) after any mRNA vaccine, 87.8% (95% CI, 75.9%–93.8%) after BioNTech vaccine and 91.7% (95% CI, 75.7%–97.2%) after Moderna vaccine. VE was estimated to be lower ≥ 3 months after dose 2 compared with < 3 months after dose 2, and among participants who were older or had underlying health conditions, although confidence intervals overlapped between subgroups. ConclusionsVE estimates generated using infection-induced antibodies were consistent with published estimates from clinical trials and observational studies that used virologic tests to confirm infection during the same period. Our findings support recommendations for eligible adults to remain up to date with COVID-19 vaccination.

Elevated SARS-CoV-2-Specific Antibody Levels in Patients with Post-COVID Syndrome.

With the routine use of effective severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines, the number of life-threatening coronavirus disease 2019 (COVID-19) courses have largely been reduced. However, multiple COVID-19 convalescents, even after asymptomatic to moderate disease, suffer from post-COVID syndrome, with relevant limitations in daily life. The pathophysiologic mechanisms of post-COVID syndrome are still elusive, with dysregulation of the immune system suggested as a central mechanism. Here, we assessed COVID-19 post-infectious symptoms (5-6 months after PCR-confirmed acute infection) together with the humoral immune response against SARS-CoV-2 in non-hospitalized COVID-19 convalescents, early (5-6 weeks) and late (5-6 months) after their first positive SARS-CoV-2 PCR result. Convalescents reporting several post-infectious symptoms (>3) showed higher anti-spike and anti-nucleocapsid antibody levels 5-6 weeks after PCR-confirmed infection with the latter remained increased 5-6 months after positive PCR. Likewise, a higher post-infectious symptom score was associated with increased antibody levels. Of note, convalescents displaying neuro-psychiatric symptoms such as restlessness, palpitations, irritability, and headache, as well as general symptoms such as fatigue/reduced power had higher SARS-CoV-2-specific antibody levels compared with asymptomatic cases. The increased humoral immune response in convalescents with post-COVID syndrome might be useful for the detection of individuals with an increased risk for post-COVID syndrome.

Serological response to vaccination in post-acute sequelae of COVID

BackgroundIndividuals with post-acute sequelae of COVID (PASC) may have a persistence in immune activation that differentiates them from individuals who have recovered from COVID without clinical sequelae. To investigate how humoral immune activation may vary in this regard, we compared patterns of vaccine-provoked serological response in patients with PASC compared to individuals recovered from prior COVID without PASC.MethodsWe prospectively studied 245 adults clinically diagnosed with PASC and 86 adults successfully recovered from prior COVID. All participants had measures of humoral immunity to SARS-CoV-2 assayed before or after receiving their first-ever administration of COVID vaccination (either single-dose or two-dose regimen), including anti-spike (IgG-S and IgM-S) and anti-nucleocapsid (IgG-N) antibodies as well as IgG-S angiotensin-converting enzyme 2 (ACE2) binding levels. We used unadjusted and multivariable-adjusted regression analyses to examine the association of PASC compared to COVID-recovered status with post-vaccination measures of humoral immunity.ResultsIndividuals with PASC mounted consistently higher post-vaccination IgG-S antibody levels when compared to COVID-recovered (median log IgG-S 3.98 versus 3.74, P < 0.001), with similar results seen for ACE2 binding levels (median 99.1 versus 98.2, P = 0.044). The post-vaccination IgM-S response in PASC was attenuated but persistently unchanged over time (P = 0.33), compared to in COVID recovery wherein the IgM-S response expectedly decreased over time (P = 0.002). Findings remained consistent when accounting for demographic and clinical variables including indices of index infection severity and comorbidity burden.ConclusionWe found evidence of aberrant immune response distinguishing PASC from recovered COVID. This aberrancy is marked by excess IgG-S activation and ACE2 binding along with findings consistent with a delayed or dysfunctional immunoglobulin class switching, all of which is unmasked by vaccine provocation. These results suggest that measures of aberrant immune response may offer promise as tools for diagnosing and distinguishing PASC from non-PASC phenotypes, in addition to serving as potential targets for intervention.

Comparison of risk factors for SARS-CoV-2 infection among healthcare workers during Omicron and Delta dominance periods in Japan

The risk factors for coronavirus disease (COVID-19) among healthcare workers (HCWs) might have changed since the emergence of the highly immune evasive Omicron variant. To compare the risk factors for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among HCWs during the Delta- and Omicron-predominant periods. Using data from repeated serosurveys among the staff of a medical research centre in Tokyo, two cohorts were established: Delta period cohort (N= 858) and Omicron period cohort (N= 652). The potential risk factors were assessed using a questionnaire. Acute/current or past SARS-CoV-2 infection was identified by polymerase chain reaction or anti-nucleocapsid antibody tests, respectively. Poisson regression was used to calculate the risk ratio (RR) of infection risk. The risk of SARS-CoV-2 infection during the early Omicron-predominant period was 3.4-fold higher than during the Delta-predominant period. Neither working in a COVID-19-related department nor having a higher degree of occupational exposure to SARS-CoV-2 was associated with an increased infection risk during both periods. During the Omicron-predominant period, infection risk was higher among those who spent ≥30min in closed spaces, crowded spaces, and close-contact settings without wearing mask (≥3 times versus never: RR: 6.62; 95% confidence interval: 3.01-14.58), whereas no such association was found during the Delta period. Occupational exposure to COVID-19-related work was not associated with the risk of SARS-CoV-2 infection in the Delta or Omicron period, whereas high-risk behaviours were associated with an increased infection risk during the Omicron period.

A COVID–19-fertőzés és a védőoltások hatásosságának vizsgálata egészségügyi dolgozókon

New variants of the SARS-CoV-2 coronavirus are constantly appearing, causing the COVID-19 pandemic. From November 2021, most infections were caused by the Omicron coronavirus variant. The aim of this prospective observational cohort study was to estimate the incidence of COVID-19 infections in the high-risk healthcare workers after two BNT162b2 mRNA Pfizer-BioNTech vaccines and the subsequent booster vaccine, as well as the effectiveness, the safety and the humoral immune response of the vaccines. We started the two Pfizer-BioNTech ((BNT162b29) vaccinations of healthcare workers of the Polyclinic of the Hospitaller Brothers of St. John between January 07 and March 08, 2021. The choice of the type and timing of the third booster vaccination was voluntary. The workers were followed up between January 07, 2021 and June 29, 2022. The infection rate, adverse events of the vaccination, risk factors to infection and the kinetics of anti-spike (S) antibody and anti-nucleocapsid (N) antibody serum level were evaluated. The data of 294 healthcare workers - 96 medical doctors, 127 nurses and 71 workers in hospital - who had at least three antibody level measurements were analyzed. The third booster vaccine was given to 280 workers, the distribution of the vaccines was the following: Pfizer-BioNTech (BNT162b29) vaccine (n = 210), Moderna COVID-19 (mRNA-1273) vaccine (n = 37), Sinopharm COVID-19 vaccine (n = 21), Janssen COVID-19 (n = 10), AstraZeneca (ChAdOx1 nCoV-19) vaccine (n = 2). Infection occurred in 121 cases (41%) during the observation period. The course of the COVID-19 infections was mostly mild (97%) and recovered within a week. During the observational period, 2 workers died: a 56-year-old woman died after two vaccinations for reason unrelated to COVID-19 infection, and a 58-year-old man died after the booster vaccination, following COVID-19 infection. The incidence of infection did not correlate with age, sex, comorbidities, smoking, occupation and BMI. The median titre of anti-S antibody serum level increased one month after the second vaccination of the basic immunization (1173.0 U/ml) and decreased slowly until the 8th month (678.5-625.8-538.0 U/ml) after the basic vaccination. One month after the booster vaccination, the median titre of anti-S antibody serum level increased significantly (16535 U/ml), and showed a decreasing trend in the 3rd month after the booster vaccination (9697.7 U/ml). An exceptionally high S antibody serum level increasing after the basic (>10000 U/mL) and booster (>60000 U/m) vaccination showed a correlation with prior COVID-19 infection. The median cut-off index (COI) of anti-N antibody was not affected by vaccination, the increasing of the titre is related to the infection. The booster vaccination had less effect on the infection caused by Omicron variant, but the course of the infection was milder. Compared to the basic immunisation, the booster vaccination caused a significant increase in the S antibody level. An exceptionally high S antibody level correlated with prior COVID-19 infection. Orv Hetil. 2023; 164(5): 163-171.

National seroepidemiological study of COVID-19 after the initial rollout of vaccines: Before and at the peak of the Omicron-dominant period in Japan.

Based on routine surveillance data, Japan has been affected much less by COVID-19 compared with other countries. To validate this, we aimed to estimate SARS-CoV-2 seroprevalence and examine sociodemographic factors associated with cumulative infection in Japan. A population-based serial cross-sectional seroepidemiological investigation was conducted in five prefectures in December 2021 (pre-Omicron) and February-March 2022 (Omicron [BA.1/BA.2]-peak). Anti-nucleocapsid and anti-spike antibodies were measured to detect infection-induced and vaccine/infection-induced antibodies, respectively. Logistic regression was used to identify associations between various factors and past infection. Among 16 296 participants (median age: 53 [43-64] years), overall prevalence of infection-induced antibodies was 2.2% (95% CI: 1.9-2.5%) in December 2021 and 3.5% (95% CI: 3.1-3.9%) in February-March 2022. Factors associated with past infection included those residing in urban prefectures (Tokyo: aOR 3.37 [95% CI: 2.31-4.91], Osaka: aOR 3.23 [95% CI: 2.17-4.80]), older age groups (60s: aOR 0.47 [95% CI 0.29-0.74], 70s: aOR 0.41 [95% CI 0.24-0.70]), being vaccinated (twice: aOR 0.41 [95% CI: 0.28-0.61], three times: aOR 0.21 [95% CI: 0.12-0.36]), individuals engaged in occupations such as long-term care workers (aOR: 3.13 [95% CI: 1.47-6.66]), childcare workers (aOR: 3.63 [95% CI: 1.60-8.24]), food service workers (aOR: 3.09 [95% CI: 1.50-6.35]), and history of household contact (aOR: 26.4 [95% CI: 20.0-34.8]) or non-household contact (aOR: 5.21 [95% CI:3.80-7.14]) in February-March 2022. Almost all vaccinated individuals (15 670/15 681) acquired binding antibodies with higher titers among booster dose recipients. Before Omicron, the cumulative burden was >10 times lower in Japan (2.2%) compared with the US (33%), the UK (25%), or global estimates (45%), but most developed antibodies owing to vaccination.

Early humoral response to COVID-19 vaccination in patients living with obesity and diabetes in France. The COVPOP OBEDIAB study with results from the ANRS0001S COV-POPART cohort

BackgroundPatients with diabetes and obesity are populations at high-risk for severe COVID-19 outcomes and have shown blunted immune responses when administered different vaccines. Here we used the ‘ANRS0001S COV-POPART’ French nationwide multicenter prospective cohort to investigate early humoral response to COVID-19 vaccination in the sub-cohort (‘COVPOP OBEDIAB’) of patients with obesity and diabetes. MethodsPatients with diabetes (n = 390, type 1 or 2) or obesity (n = 357) who had received two vaccine doses and had no history of previous COVID-19 infection and negative anti-nucleocapsid (NCP) antibodies were included and compared against healthy subjects (n = 573). Humoral response was assessed at baseline, at one month post-first dose (M0) and one-month post-second dose (M1), through percentage of responders (positive anti-spike SARS-CoV-2 IgG antibodies (Sabs), geometric means of Sabs; BAU/mL), proportion of individuals with anti-RBD antibodies, and proportion of individuals with anti-SARS-CoV-2-specific neutralizing antibodies (Nabs). Potential clinical and biological factors associated with weak response (defined as Sabs < 264 BAU/mL) and presence of non-reactive anti-RBD antibodies at M1 were evaluated. Univariate and multivariate regressions were performed to estimate crude and adjusted coefficients with 95 % confidence intervals. Poor glycemic control was defined as HbA1c ≥ 7.5 % at inclusion. ResultsPatients with diabetes, particularly type 2 diabetes, and patients with obesity were less likely to have positive Sabs and anti-RBD antibodies after the first and second dose compared to controls (p < 0.001). At M1, we found Sabs seroconversion in 94.1 % of patients with diabetes versus 99.7 % in controls, anti-RBD seroconversion in 93.8 % of patients with diabetes versus 99.1 % in controls, and Nabs seroconversion in 95.7 % of patients with diabetes versus 99.6 % in controls (all p < 0.0001). Sabs and anti-RBD seroconversion at M0 and M1 were also significantly lower in obese patients than controls, at respectively 82.1 % versus 89.9 % (p = 0.001; M0 Sabs), 94.4 % versus 99.7 % (p 0.001; M1 Sabs), 79.0 % vs 86.2 % (p = 0.004 M0 anti-RBD), and 96.99 % vs 99.1 % (p = 0.012 M1 anti-RBD). The factors associated with low vaccine response (BAU < 264/mL) in patients with diabetes were chronic kidney disease (adjusted OR = 6.88 [1.77;26.77], p = 0.005) and poor glycemic control (adjusted OR = 3.92 [1.26;12.14], p = 0.018). In addition, BMI ≥ 40 kg/m2 was found to be associated with a higher vaccine response (adjusted OR = 0.10 [0.01;0.91], p = 0.040) than patients with BMI < 40 kg/m2. ConclusionCOVID-19 vaccine humoral response was lower in patients with obesity and diabetes one month after second dose compared to controls, especially in diabetic patients with CKD or inadequate glycemic control. These findings point to the need for post-vaccination serological checks in these high-risk populations.

SARS-CoV-2 epidemiology, antibody dynamics, and neutralisation capacity in Irish healthcare workers in the era of booster COVID-19 vaccinations.

The PRECISE Study, a multi-phase cross-sectional seroprevalence study of anti-SARS-CoV-2 antibodies in Irish healthcare workers (HCW) investigated: (1) risk factors for SARS-CoV-2 seropositivity, (2) the durability of antibody responses in a highly vaccinated HCW cohort, and (3) the neutralisation capacity of detected antibodies, prior to booster COVID-19 vaccination. Serology samples were collected across two hospital sites in November 2021 and analysed using the Roche Elecsys Anti-SARS-CoV-2/Elecsys-S Anti-SARS-CoV-2 assays to detect anti-nucleocapsid (N) and anti-spike (S) antibodies respectively. Paired serology results from prior study phases were used to analyse changes in individual HCW serostatus over time. Risk-factors for SARS-CoV-2 infection were assessed for demographic and work-related factors. Antibody neutralisation capacity was assessed in a subset of samples via an in vitro ACE2 binding enzyme-linked immunosorbent assay. 2,344 HCW samples were analysed. Median age was 43 years (IQR 33-50) with 80.5% (n = 1,886) female participants. Irish (78.9%, n = 1,850) and Asian (12.3%, n = 288) were the most commonly reported ethnicities. Nursing/midwifery (39.3%, n = 922) was the most common job role. 97.7% of participants were fully vaccinated, with Pfizer (81.1%, n = 1,902) and AstraZeneca (16.1%, n = 377) the most common vaccines received. Seroprevalence for anti-SARS-CoV-2 antibodies indicating prior infection was 23.4%, of these 33.6% represented previously undiagnosed infections. All vaccinated participants demonstrated positive anti-S antibodies and in those with paired serology, no individual demonstrated loss of previously positive anti-S status below assay threshold for positivity. Interval loss of anti-N antibody positivity was demonstrated in 8.8% of previously positive participants with paired results. Risk factors for SARS-CoV-2 seropositivity suggestive of previous infection included age 18-29 years (aRR 1.50, 95% CI 1.19-1.90, p < 0.001), India as country of birth (aRR 1.35, 95% CI 1.01-1.73, p = 0.036), lower education level (aRR 1.35, 95% CI 1.11-1.66, p = 0.004) and HCA job role (aRR 2.12, 95% CI 1.51-2.95, p < 0.001). Antibody neutralisation varied significantly by anti-SARS-CoV-2 antibody status, with highest levels noted in those anti-N positive, in particular those with vaccination plus previous SARS-CoV-2 infection. All vaccinated HCWs maintained anti-S positivity prior to COVID-19 booster vaccination, however anti-N positivity was more dynamic over time. Antibody neutralisation capacity was highest in participants with COVID-19 vaccination plus prior SARS-CoV-2 infection.

Cross-Canada Variability in Blood Donor SARS-CoV-2 Seroprevalence by Social Determinants of Health.

We compared the seroprevalence of SARS-CoV-2 anti-nucleocapsid antibodies in blood donors across Canadian regions in 2021. The seroprevalence was the highest in Alberta and the Prairies, and it was so low in Atlantic Canada that few correlates were observed. Being male and of young age were predictive of seropositivity. Racialization was associated with higher seroprevalence in British Columbia and Ontario but not in Alberta and the Prairies. Living in a materially deprived neighborhood predicted higher seroprevalence, but it was more linear across quintiles in Alberta and the Prairies, whereas in British Columbia and Ontario, the most affluent 60% were similarly low and the most deprived 40% similarly elevated. Living in a more socially deprived neighborhood (more single individuals and one parent families) was associated with lower seroprevalence in British Columbia and Ontario but not in Alberta and the Prairies. These data show striking variability in SARS-CoV-2 seroprevalence across regions by social determinants of health. IMPORTANCE Canadian blood donors are a healthy adult population that shows clear disparities associated with racialization and material deprivation. This underscores the pervasiveness of the socioeconomic gradient on SARS-CoV-2 infections in Canada. We identify regional differences in the relationship between SARS-CoV-2 seroprevalence and social determinants of health. Cross-Canada studies, such as ours, are rare because health information is under provincial jurisdiction and is not available in sufficient detail in national data sets, whereas other national seroprevalence studies have insufficient sample sizes for regional comparisons. Ours is the largest seroprevalence study in Canada. An important strength of our study is the interpretation input from a public health team that represented multiple Canadian provinces. Our blood donor seroprevalence study has informed Canadian public health policy at national and provincial levels since the start of the SARS-CoV-2 pandemic.

Rhesus Blood Group C (RH2) is Associated with Protection against SARS-Cov-2 Infections

Background: Previous reports showed a 40% reduction in the odds of being HIV-positive in RH2-heterozygotes. In addition, those lacking the gene were 24 times and 33 times more likely to be HIV-infected than heterozygotes or homozygotes, respectively. A four-year longitudinal study observed lower HIV viral load and slower disease progression in RH2-positive individuals. Thus, the current study sought to establish if the same phenomenon applied to SARS-CoV-2 infections. We also compared the plasma levels of SARS-CoV-2 anti-spike and anti-nucleocapsid protein antibodies following full vaccination against COVID-19. Materials and Methods: Erythrocytes were phenotyped using anti-C and anti-c. Antibodies against SARS-CoV-2 were also measured in plasma of fully vaccinated persons (Oxford Astra-Zeneca, Johnson &amp; Johnson, Pfizer/BioNTech, Sinovac, and Moderna vaccines) and compared across RH2 phenotypes. Results: RH2 expression on erythrocytes (n=319) was associated with lower odds for SARS-CoV-2 infection (OR= 0.42, 95%CI: 0.22-0.80, p=0.008). The strength of the serological reaction between anti-C and erythrocytes was predictive of a COVID-19 diagnosis (Mantel-Haenszel Chi Square = 9.44, p=0.002). However, there was no difference in the levels of anti-SARS-CoV-2 antibodies across categories of RH2, regardless of the vaccine taken. Discussion: RH2-positivity and stronger anti-C reaction were associated with protection against SARS-CoV-2, practically duplicating previous observations regarding HIV infection. Since both pathogens are ssRNA viruses, the primary mechanism likely involves Toll-like receptors that favor a TH1 response. The TH1 polarization is also suggested by protection against infection devoid of a superior humoral response. Further investigations could potentially provide a new approach to treat or prevent both viruses and other single-stranded RNA viruses.

Anti-nucleocapsid IgG antibodies in SARS-CoV-2 recovered health care workers: One year follow-up study.

Objective: The objective of this study was to evaluate the magnitude and durability of the anti-nucleocapsid-IgG antibody titer in healthcare workers previously infected with SARS-CoV-2 for a period of 12months.Methods: This study examined blood samples for SARS-CoV-2-specific IgG collected periodically from 120 healthcare workers previously infected with SARS-CoV-2 (confirmed by RT-PCR) and followed longitudinally up to 12months from their enrolment into the study.Results: The median anti-N-IgG antibody level identified at 3months was 23.7 CO-index (IQR: 9.13-50.27) and increased to 32.9 CO-index (IQR: 11.8-84.4) at 6months. At 9months, the median anti-N-IgG antibody level started to wane in the subsequent time and was dropped to 14 CO-index (IQR: 3.4-37.6) and declined further to 9.8 CO-index at 12months (IQR: 2.8-9.8). When classified by age groups, the only statistically significant difference in anti-N-IgG between the two age groups (≤30years and >30years) was identified at 12month time point (median difference 8.06, p = 0.035). Spearman correlation coefficient was negatively associated between anti-N-IgG and time interval (r = -0.255, p = 0.000) but was not statistically significant with age of a patient (p > 0.05).Conclusions: In conclusion, SARS-CoV-2 antibody levels started declining after 6months but remained detectable in the majority of patients up to 12months.

Seroprevalence of antibodies against SARS-CoV-2 in the Valencian Community (Spain) as of October 2022

ObjectiveTo estimate the seroprevalence of SARS-CoV-2 antibodies in the Valencian Community (Spain) in October 2022, when BA.5 was the predominant variant. MethodCross-sectional, region-wide, population-based serosurvey study in 88 randomly selected primary care centers of the Valencian Community. ResultsSeroprevalence of anti-nucleocapsid (indicative of past infection) and total receptor binding domain (indicative of past infection or vaccination) antibodies was 71.0% (confidence interval [CI]: 67.8-74.2) and 98.4% (CI: 97.5-99.3), respectively. 66.7% (CI: 63.4-70.0) of the population shows hybrid immunity, but only 43.2% in those 80 and over. ConclusionsThe high proportion of hybrid immunity detected is relevant for public health strategies. A second vaccination booster was advisable in the elderly population.

Severe acute respiratory syndrome coronavirus 2 seroprevalence and longitudinal antibody response following natural infection in pregnancy: A prospective cohort study.

Antenatal care provides unique opportunities to assess severe acute respiratory syndrome coronavirus 2 seroprevalence and antibody response duration after natural infection detected during pregnancy; transplacental antibody transfer may inform peripartum and neonatal protection. We estimated seroprevalence and durability of antibodies from natural infection (anti-nucleocapsid immunoglobulin G) among pregnant people, and evaluated transplacental transfer efficiency. We conducted a cross-sectional study to measure severe acute respiratory syndrome coronavirus 2 seroprevalence, and a prospective cohort study to longitudinally measure anti-nucleocapsid immunoglobulin G responses and transplacental transfer of maternally derived anti-nucleocapsid antibodies. We screened pregnant people for the seroprevalence study between 9 December 2020 and 19 June 2021 for anti-nucleocapsid immunoglobulin G in Seattle, Washington. We enrolled anti-nucleocapsid immunoglobulin G positive people from the seroprevalence study or identified through medical records with positive reverse transcription polymerase chain reaction or antigen positive results in a prospective cohort between 9 December 2020 and 9 August 2022. In the cross-sectional study (N = 1284), 5% (N = 65) tested severe acute respiratory syndrome coronavirus 2 anti-nucleocapsid immunoglobulin G positive, including 39 (60%) without prior positive reverse transcription polymerase chain reaction results and 42 (65%) without symptoms. In the prospective cohort study (N = 107 total; N = 65 from the seroprevalence study), 86 (N = 80%) had anti-nucleocapsid immunoglobulin G positive results during pregnancy. Among 63 participants with delivery samples and prior anti-nucleocapsid positive results, 29 (46%) were anti-nucleocapsid immunoglobulin G negative by delivery. Of 34 remaining anti-nucleocapsid immunoglobulin G positive at delivery with paired cord blood, 19 (56%) had efficient transplacental anti-nucleocapsid immunoglobulin G antibody transfer. Median time from first anti-nucleocapsid immunoglobulin G positive to below positive antibody threshold was 19 weeks and did not differ by prior positive reverse transcription polymerase chain reaction status. Maternally derived severe acute respiratory syndrome coronavirus 2 antibodies to natural infection may wane before delivery. Vaccines are recommended for pregnant persons to reduce severe illness and confer protection to infants.

1941. Describing the immune response kinetics to mRNA COVID-19 vaccines among previously SARS-CoV-2–infected and –uninfected nursing home residents, a prospective longitudinal observational cohort evaluation—Georgia, October 2020 – September 2021

Abstract Background To describe post-COVID-19 vaccination [fully vaccinated (FV) and first booster] immune response and occurrence of reinfection ( &amp;gt;90 days from prior infection) in nursing home residents (NHr) with/without evidence of prior SARS-CoV-2 infection. Methods In a longitudinal prospective cohort of 36 NHr from 3 NHs, interviews, chart abstractions, and specimens [blood and anterior nasal swabs (ANs)] were collected at baseline and monthly visits. ANs underwent molecular and BinaxNOW™ antigen testing. Quantitative Meso Scale Discovery platform tested blood specimens for anti-spike (S) protein and anti-nucleocapsid (N) antibodies. In addition, in a subset (n=13), S-specific memory B cells (MBCs) were tested with ELISpot assays. Results The cohort's median age was 72 years; 46% male, 64% White Non-Hispanic, 80% had ≥3 comorbidities, and 29 (81%) had prior SARS-CoV-2 infection. Of 36, 76% received Pfizer-BioNTech and 24% Moderna homologous vaccine. The median distribution of anti-S IgG concentrations among those with prior infection increased 15‒30 days post-FV, remained stable for 90 days, and declined by 120 days. The anti-S IgG remained above the estimated vaccine effectiveness (VE) thresholds published [Pfizer-BioNTech (95% VE: 530 BAU/ml), Moderna (90% VE: 298 BAU/ml)]. Among those without previous infection, anti-S IgG declined after 60 days and stayed near the VE thresholds until a recent infection/booster. Age, sex, and comorbidities had no appreciable impact on anti-S IgG. From enrollment to November 2021, 1of 29 had reinfection. From December 2021 to January 2022, 2 of 7 had a new infection, and 4 of 29 had reinfection, as shown by anti-N IgG rise. Persistently low numbers of total and anti-S MBC were seen across the evaluation, even with post-booster anti-S MBC rise. There was an immediate rise in anti-S IgG concentrations in all participants post-booster, irrespective of recent infection. Conclusion These findings from a NH convenience cohort suggest that prior SARS-CoV-2 infection has a pronounced immunomodulatory enhancing effect on the magnitude and duration of FV immune response. The decline of anti-S antibodies post-FV and rise after booster supported the booster recommendation in this cohort. The low MBC counts indicate immunosenescence in this high-risk population. Disclosures Hollis Houston, BA, Fidelity: Stocks/Bonds.

1958. Longitudinal SARS-COV-2 anti-spike antibody response in pregnant people with natural infection and variable vaccine uptake

Abstract Background Natural SARS-CoV-2 infection results in anti-nucleocapsid (N) and anti-spike (S) antibody (Ab) development. Anti-S Ab response (conferred by infection and/or vaccination) is more closely associated with protection. We evaluated anti-N/S Ab responses in vaccinated (&amp;gt; 1 dose) and unvaccinated pregnant people with prior SAR-CoV-2 infection. Methods During January 2021-March 2022, we enrolled participants with SARS-CoV-2 infection identified in pregnancy (26 via anti-N IgG+; 52 via prior RT-PCR+). Baseline, 1, 2, 3, 6, and 12 months, and delivery samples were tested for anti-N (index ≥ 1.4 positive) and anti-S (≥ 50 AU/mL positive) IgG Ab by Abbott Architect. Kaplan-Meier methods were used to measure Ab response duration. Results Among 78 participants, 62 (79%) enrolled in pregnancy (median 27 weeks gestation), and 16 (21%) at delivery/postpartum (median 2 weeks); 34 (44%) had received ≥1 vaccine prior to initial Ab testing. At baseline, 59 (75%) participants had concordant anti-N/S positive results (median anti-N index 3.58 [IQR 2.01-5.82], median anti-S 5529 AU/ml [IQR 687-25000]). Anti-S IgG was higher (25000 vs 774, p&amp;lt; 0.001) among participants receiving ≥1 vaccine vs no vaccine, while anti-N IgG indices were similar. Among 59 participants with initial anti-N IgG+ results, median time to anti-N IgG negative results was 31 weeks after first RT-PCR+ (median 17 weeks after first anti-N IgG+ result). Only 1 (unvaccinated) participant had an anti-S IgG negative result by 22 weeks after first RT-PCR+ result. Among 30 participants with delivery samples (median 16 weeks after RT-PCR+, 12 weeks after baseline anti-N IgG+ samples), 15 (52%) remained anti-N IgG+; 29 (97%) remained anti-S IgG+. Anti-S IgG was higher (25000 vs 826 AU/ml, p&amp;lt; 0.001) among participants receiving ≥ 1 vaccine vs. no vaccine prior to delivery. Conclusion Among pregnant persons with prior SARS-CoV-2 infection, duration of anti-S IgG response was longer than anti-N IgG irrespective of vaccine status; vaccination during pregnancy was associated with higher anti-S levels at baseline and delivery. While anti-S IgG were detectable for ≥ 6 months, longer term follow-up is needed to assess durability of hybrid immunity vs. infection alone and has implications for maternal and infant protection. Disclosures Sylvia M. LaCourse, MD, MPH, Aurum Institute: Advisor/Consultant|Merck: Grant/Research Support Alexander L. Greninger, MD, PhD, Abbott: Contract Testing|Cepheid: Contract Testing|Gilead: Grant/Research Support|Gilead: Contract Testing|Hologic: Contract Testing|Merck: Grant/Research Support|Novavax: Contract Testing|Pfizer: Contract Testing Alisa B. Kachikis, MD, MSc, GSK: Advisor/Consultant|Merck: Grant/Research Support|Pfizer: Advisor/Consultant Janet A. Englund, MD, AstraZeneca: Advisor/Consultant|AstraZeneca: Grant/Research Support|GlaxoSmithKline: Grant/Research Support|Meissa Vaccines: Advisor/Consultant|Merck: Grant/Research Support|Pfizer: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant Alison L. Drake, PhD, MPH, Merck: Grant/Research Support.