Primary Vaccination Research Articles

Barriers to initial COVID-19 booster among U.S. adults who completed a primary vaccine series in the CHASING COVID cohort, September 2021 - October 2022.

It is crucial to understand factors associated with COVID-19 booster uptake in the U.S. given the updated COVID-19 vaccine recommendations. Using data from a national prospective cohort (N=4,616) between September 2021-October 2022, we examined socioeconomic, demographic, and behavioral factors of initial booster uptake among participants fully-vaccinated with the primary COVID-19 vaccines series. Cox proportional hazards models were used to estimate the associations of each factor with time to initial booster uptake. Most participants (86.5%) reported receiving their initial booster. After adjusting for age, race/ethnicity, education, region, and employment, participants with greater risk for severe COVID-19 had similar booster uptake compared with those with lower risk (aHR: 1.04; 95% CI: 0.95, 1.14). Participants with greater barriers to healthcare (aHR: 0.89; 95% CI: 0.84, 0.96), food insecurity (aHR: 0.82; 95% CI: 0.75, 0.89), and housing instability (aHR: 0.81; 95% CI: 0.73, 0.90) were less likely to report receiving initial booster compared with those without those barriers. Factors motivating the decision to vaccinate changed from safety-related concerns for the primary series to perceived need for the booster. It is key to address economic and health access barriers to achieve equitable COVID-19 vaccine uptake and continued protection against COVID-19.

The Impact of Smoking on Long-Term Protection Following Hepatitis B Vaccination: A 24-Year Cohort Study.

The hepatitis B vaccination-induced immune response has been demonstrated to be associated with a number of factors, including age, sex, BMI, and the presence of comorbidities. Additionally, modifiable determinants such as smoking have been identified as influencing the response to vaccination. However, despite the evidence that smokers are at an increased risk of not responding to vaccination, the long-term effects of smoking on antibody persistence remain poorly understood. This study aims to assess the impact of smoking habits on long-term immunity following the primary vaccination cycle. Participants were required to have received a standard three-dose vaccine schedule in childhood, without subsequent doses, and to be between 18 and 24 years of age. Data on age, sex, BMI, age of administration of the first vaccine dose, and time between doses were collected. An antibody concentration < 10 IU/L was considered as non-protective. A total of 2133 individuals were included, 14.2% of whom were smokers. The mean age was 20.28 ± 0.92 years. The probability of having a non-protective antibody concentration was significantly higher in smokers than in non-smokers (AOR: 1.287; 95% CI: 1.002-1.652). The detrimental effects of smoking extend beyond the immediate effects on the vaccine response, also impairing the long-term immune response in individuals who received vaccinations during childhood.

Vaccine challenges in CLL: a comprehensive exploration of efficacy of SARS-CoV-2 immunization for patients with chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) is characterized by disease- and treatment-related immunosuppression. Patients with CLL comprise a vulnerable population to coronavirus disease 2019 (COVID-19), while the protective effect of COVID-19 vaccination remains uncertain.We conducted a systematic review to evaluate published data reporting response to COVID-19 vaccination in patients with CLL. The primary outcome was the rate of seropositivity after full primary vaccination, while secondary outcomes were rates of positive neutralizing antibodies, cellular responses, and adverse events. Response after booster doses of vaccination was also evaluated.Twenty-three studies of full primary vaccination (12 CLL-specific with 1747 patients, 11 with mixed hematologic diseases including 1044 patients with CLL) with a total of 2791 patients, and eight studies on booster doses with 389 patients were included in the analysis. The serologic response varied between studies with a median of 55%. Where reported, the median neutralizing antibody response rate was 61.2% and the cellular response rate was 44.2%. Poor serologic response was noted in patients under active treatment with anti-CD20 monoclonal antibodies, BCL2, and BTK inhibitors.The present review highlights the substantially impaired humoral and cellular response to COVID-19 vaccination in patients with CLL with patients under active treatment being the most vulnerable.

Randomized controlled trial reveals no benefit to a 3-month delay in COVID-19 mRNA booster vaccine.

BACKGROUNDThere is uncertainty about the timing of booster vaccination against COVID-19 in highly vaccinated populations during the present endemic phase of COVID-19. Studies focused on primary vaccination have previously suggested improved immunity with a longer interval between the first and second vaccine doses.METHODSWe conducted a randomized, controlled trial (November 2022-August 2023) and assigned 52 fully vaccinated adults to an immediate or a 3-month delayed bivalent Spikevax mRNA booster vaccine. Follow-up visits were completed for 48 participants (n = 24 per arm), with collection of saliva and plasma samples following each visit.RESULTSThe rise in neutralizing antibody responses to ancestral and Omicron strains were almost identical between the immediate and delayed vaccination arms. Analyses of plasma and salivary antibody responses (IgG, IgA), plasma antibody-dependent phagocytic activity, and the decay kinetics of antibody responses were similar between the 2 arms. Symptomatic and asymptomatic SARS-CoV-2 infections occurred in 49% (21 of 49) participants over the median 11.5 months of follow-up and were also similar between the 2 arms.CONCLUSIONSOur data suggest that there was no benefit in delaying COVID-19 mRNA booster vaccination in preimmune populations during the present endemic phase of COVID-19.TRIAL REGISTRATIONAustralian New Zealand Clinical Trials Registry number 12622000411741 (https://anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12622000411741).FUNDINGNational Health and Medical Research Council, Australia (program grant App1149990) and Medical Research Future Fund (App2005544).

Child COVID-19 vaccine uptake among participants of the 2015 Pelotas (Brazil) Birth Cohort Study

ObjectiveTo analyze COVID-19 vaccine uptake in children and to investigate factors associated with two outcomes variables: (a) not even beginning; (b) not completing the COVID-19 vaccine series. MethodsWe used data of children aged 6–7 years from the 2015 Pelotas c Birth Cohort Study. COVID-19 vaccination status was collected from immunization cards and National Immunization Program Information System. Adjusted analyses were performed using a hierarchical model to identify factors associated with the two study outcomes. ResultsAmong 3867 children, 20.7 % (95 % CI, 19.5 %–22.0 %) did not even begin the 2-dose primary COVID-19 vaccine series, and 28.2 % (95 % CI, 26.6 %–29.8 %) did not complete the series with the second dose. Children not even beginning the COVID-19 vaccine series were more likely to have a White mother, not to have obesity, to have a history of COVID-19 infection, to have received non-recommended drugs for COVID-19, to be afraid of needles, and to have an incomplete diphtheria-tetanus-pertussis (DTP) and poliovirus immunization schedule. Not completing the 2-dose series was associated with lower maternal age and education, mother’s self-identification as White or Brown, lower household income, lack of access to health services, not having completed the DTP and poliovirus immunization schedule and living with a person with a history of infection with COVID-19. ConclusionThe results highlight a vaccine-hesitant parents’ group who chose not beginning the COVID-19 vaccine series of their children and, another group of parents who failure to complete the child’s series due to difficulty accessing health services.

Memory B cell proliferation drives differences in neutralising responses between ChAdOx1 and BNT162b2 SARS-CoV-2 vaccines.

Vaccination against COVID-19 has been pivotal in reducing the global burden of the disease. However, Phase III trial results and observational studies underscore differences in efficacy across vaccine technologies and dosing regimens. Notably, mRNA vaccines have exhibited superior effectiveness compared to Adenovirus (AdV) vaccines, especially with extended dosing intervals. Using in-host mechanistic modelling, this study elucidates these variations and unravels the biological mechanisms shaping the immune responses at the cellular level. We used data on the change in memory B cells, plasmablasts, and antibody titres after the second dose of a COVID-19 vaccine for Australian healthcare workers. Alongside this dataset, we constructed a kinetic model of humoral immunity which jointly captured the dynamics of multiple immune markers, and integrated hierarchical effects into this kinetics model, including age, dosing schedule, and vaccine type. Our analysis estimated that mRNA vaccines induced 2.1 times higher memory B cell proliferation than AdV vaccines after adjusting for age, interval between doses and priming dose. Additionally, extending the duration between the second vaccine dose and priming dose beyond 28 days boosted neutralising antibody production per plasmablast concentration by 30%. We also found that antibody responses after the second dose were more persistent when mRNA vaccines were used over AdV vaccines and for longer dosing regimens. Reconstructing in-host kinetics in response to vaccination could help optimise vaccine dosing regimens, improve vaccine efficacy in different population groups, and inform the design of future vaccines for enhanced protection against emerging pathogens.

Comparative safety and efficacy of autogenous vaccine administrated by different routes against furunculosis caused by Aeromonas salmonicida sub. salmonicida in large Rainbow trout (Oncorhynchus mykiss)

The development and growth of fish farming are hindered by viral and bacterial infectious diseases, which necessitate effective disease control measures. Furunculosis, primarily caused by Aeromonas salmonicida, stands out as a significant bacterial disease affecting salmonid fish farms, particularly rainbow trout. Vaccination has emerged as a crucial tool in combating this disease. The objective of this experiment was to assess and compare the efficacy and duration of different vaccine protocols against furunculosis in large trout under controlled rearing conditions, utilizing single and booster administrations via intraperitoneal, oral, and immersion routes. Among the various vaccination protocols tested, only those involving intraperitoneal injection, administered at least once, proved truly effective in preventing the expression of clinical signs of furunculosis and reducing mortality rates. A single intraperitoneal administration provided protection for up to 2352°-days, equivalent to approximately 5 months in water at 16 °C. However, intraperitoneal vaccination may lead to reduced growth in the fish due to resultant intraperitoneal adhesions. Additionally, protocols incorporating booster doses via intraperitoneal injection demonstrated efficacy regardless of the administration route of the primary vaccination. Nevertheless, the use of booster vaccinations via the intraperitoneal route did not confer any significant advantage over a single intraperitoneal injection in terms of efficacy.

Community Health Volunteers' experiences of implementing COVID-19 vaccine education and promotion in Kenya: a qualitative descriptive study.

Vaccination was a key measure in the COVID-19 pandemic response, though much work was needed to promote vaccine uptake and acceptance. In Kenya, Community Health Volunteers (CHVs) played a key role in vaccine education and promotion. We conducted this study to explore CHVs' experiences of implementing COVID-19 vaccine education and promotion during the pandemic to increase COVID-19 vaccine uptake in two areas of Kenya. In a qualitative descriptive study, we conducted 30 structured in-depth interviews with 20 CHVs and 10 Community Health Assistants from rural Kilifi County and Kangemi, an urban informal settlement of Nairobi County in Kenya between April 2022 and July 2022. Thematic analysis generated five key themes in relation to CHVs' experiences of implementing COVID-19 vaccine education and promotion: Five key themes emerged regarding CHVs' experiences of implementing COVID-19 vaccine education and promotion: (1) vaccine preferences influenced acceptance, (2) the fear of side effects was a barrier, (3) misinformation was widespread (4) lack of trust in government and politicization of vaccines was a barrier, and (5) CHVs' efforts were a facilitator to increased uptake. Extensive community outreach from CHVs contributed to the high uptake of primary vaccines and boosters during the COVID-19 pandemic. CHVs acting as role models by receiving vaccinations first was particularly important in influencing communities to accept vaccinations. Findings provide evidence for prioritizing CHVs in the planning and implementation of future vaccination initiatives in Kenya and other countries.

A phase 2 study of a brachyury-targeting vaccine in combination with radiation therapy for the treatment of advanced chordoma.

This was a single-arm, phase 2 clinical trial of Bavarian Nordic (BN)-Brachyury vaccine plus radiotherapy (RT) designed to determine the objective response rate (ORR), progression-free survival (PFS), and safety of the combination in chordoma. A total of 29 adult patients with advanced chordoma were treated with two subcutaneous priming vaccine doses of modified vaccinia Ankara-Bavarian Nordic (MVA-BN)-Brachyury and one vaccine dose of fowlpox virus (FPV)-Brachyury before RT. After RT, booster vaccinations were given with FPV-Brachyury every 4 weeks for 4 doses, then every 12 weeks (week 110). A minimum RT dose of >8 Gy in one fraction for each target was required. Response was evaluated by modified Response Evaluation Criteria in Solid Tumors 1.1 (mRECIST), where only radiated lesions were considered targets, and by standard RECIST 1.1 in a subset of patients. Two of 26 evaluable patients experienced durable partial response (PR) (ORR of 7.7%; 90% confidence interval [CI], 2.6-20.8]) by mRECIST 1.1. A total of 21 patients (80.8%; 90% CI, 65.4-90.3) had stable disease, and three patients (11.5%; 90% CI, 4.7-25.6) had progressive disease as best response per mRECIST 1.1. Median PFS was not reached during the study. This trial confirms the safety of BN-Brachyury and RT. Although the study did not meet the predefined study goal of four responses in 29 patients, we did observe two PRs and a PFS of greater than 2 years. For a vaccine-based study in chordoma, an ultra-rare disease where response rates are low, a randomized study or novel trial designs may be required to confirm activity.

Enhancing cross-protection against influenza by heterologous sequential immunization with mRNA LNP and protein nanoparticle vaccines

Enhancing influenza vaccine cross-protection is imperative to alleviate the significant public health burden of influenza. Heterologous sequential immunization may synergize diverse vaccine formulations and routes to improve vaccine potency and breadth. Here we investigate the effects of immunization strategies on the generation of cross-protective immune responses in female Balb/c mice, utilizing mRNA lipid nanoparticle (LNP) and protein-based PHC nanoparticle vaccines targeting influenza hemagglutinin. Our findings emphasize the crucial role of priming vaccination in shaping Th bias and immunodominance hierarchies. mRNA LNP prime favors Th1-leaning responses, while PHC prime elicits Th2-skewing responses. We demonstrate that cellular and mucosal immune responses are pivotal correlates of cross-protection against influenza. Notably, intranasal PHC immunization outperforms its intramuscular counterpart in inducing mucosal immunity and conferring cross-protection. Sequential mRNA LNP prime and intranasal PHC boost demonstrate optimal cross-protection against antigenically drifted and shifted influenza strains. Our study offers valuable insights into tailoring immunization strategies to optimize influenza vaccine effectiveness.

Effect of Rabies Booster Vaccination on Antibody Levels in African Wild Dogs (Lycaon pictus).

Rabies is a highly virulent viral disease that has been associated with large-scale population declines of the endangered African wild dog (Lycaon pictus). Rabies vaccination may be a valuable conservation tool in this species, but studies indicate that a single dose does not always confer protective immunity. We examined 47 serum samples from 22 captive African wild dogs (sampled opportunistically for other purposes) to assess whether serum antibody levels after vaccination correlated with the number of doses received and whether other factors affected outcomes. Results of the fluorescent antibody virus neutralization test showed that median antibody titers were 0.085 IU/mL prevaccination, 0.660 IU/mL after a single vaccination, and 22.150 IU/mL after a booster vaccination. Antibody titers above 0.5 IU/mL, internationally accepted as the threshold for seroconversion, were found in none of the samples taken prevaccination, 66.67% of samples taken after primary vaccination, and 90.90% of samples collected after booster vaccination. This study illustrates the probable protective benefit a rabies booster vaccination may provide in African wild dogs and serves as a basis for future research to improve vaccination protocols contributing to the conservation of this endangered species.

The association between screen time exposure, parent depression, and development of social communication skills among preschool children in Qassim Region

BackgroundScreen exposure among children continues to increase worldwide. It has negative effects on children of developmental age, including obesity, poor attention, sleep disorders, vision problems, language delays, and deficits in communication skills. It has been reported that parental depression is associated with both increased screen time for children and poor function and skills in children. However, other studies have reported no association between screen time and parental depression.Research methodologyA cross-sectional study was conducted using a convenience sample of 340 parents of 4- to 6-year-old children in the Qassim Region of Saudi Arabia. Data were collected from the primary health care vaccination clinic by contacting parents of children aged 4 to 6 years to fill out the Social Communication Questionnaire (SCQ) for the child and the Patient Health Questionnaire-9 (PHQ9) for the parents.Research resultsWe conducted a regression analysis to assess the influence of screen time exposure on social communication skills (SCQ score). The results of this study indicated that there was no significant effect observed (B = 0.283, P > 0.05), indicating that a positive correlation between screen time usage and SCQ score may not apply to the entire population. Conversely, we discovered a crucial link between screen time exposure and parental depression (PHQ), as it displayed noteworthy impact values (B = 1.136, P < 0.05), indicating an affirmative correlation between them. In addition, our results also indicated apparent positive associations between parental depression and SCQ scores (B = 0.229, P < 0.05).ConclusionOur findings revealed that there was a significant association between parental depression and both screen time exposure and SCQ score, while there was no correlation between screen time exposure and SCQ score.

Immunogenicity and safety of an 18-month booster dose of the VLA15 Lyme borreliosis vaccine candidate after primary immunisation in healthy adults in the USA: results of the booster phase of a randomised, controlled, phase 2 trial

Incidence rates of Lyme borreliosis, a tickborne disease attributed to infection by Borrelia species, are increasing, and limitations to existing treatments potentiate the possibility of severe outcomes. Nevertheless, there are no licensed vaccines for Lyme borreliosis prevention in humans. This study investigated the immunogenicity and safety of a booster dose of VLA15, an investigational outer surface protein A (OspA)-based Lyme borreliosis vaccine that has previously shown safety and immunogenicity when administered as a primary vaccination series, following a primary VLA15 vaccination series. We report the results of the booster phase of a randomised, observer-blinded, placebo-controlled, multicentre, phase 2 study that enrolled healthy adults aged 18-65 years from five US clinical study centres to receive 135 μg or 180 μg VLA15 or placebo at months 0, 2, and 6 in the main study phase. Participants who received 180 μg VLA15 in the main study phase and did not have relevant protocol deviations were eligible for the booster phase (months 18-30). Participants were randomly reassigned (2:1) to receive an intramuscular injection of a VLA15 booster or placebo 1 year after the completion of primary vaccination (month 18) via a randomisation list generated by an unmasked statistician with a block size of six. Individuals involved in data safety monitoring, rerandomisation, vaccine handling, and vaccine accountability were unmasked; the study sponsor and statisticians were only unmasked after analysis of data up to 1 month after booster administration. All other individuals remained masked throughout the booster phase. The outcomes for the booster phase were the immunogenicity (evaluated in the booster per-protocol population) and safety (evaluated for all participants who received the booster) of the booster dose up to month 30. The study is registered at ClinicalTrials.gov (NCT03970733) and is completed. Between Feb 4 and March 23, 2021, 58 participants (28 men and 30 women) were screened, randomly assigned, and received VLA15 (n=39) or placebo (n=19). One participant in the placebo group was lost to follow-up. The IgG geometric mean titres for each OspA serotype (serotypes 1-6) in the VLA15 group peaked at 1 month after the booster dose (1277·0 U/mL [95% CI 861·8-1892·3] to 2194·5 U/mL [1566·8-3073·7] vs 23·6 U/mL [18·1-30·8] to 36·8 U/mL [26·4-51·3] in the placebo group [p<0·0001 for all serotypes]), remained elevated at month 24 (137·4 U/mL [95·8-196·9] to 265·8 U/mL [202·9-348·2] vs 22·3 U/mL [17·7-28·0] to 29·1 U/mL [20·8-40·6] in the placebo group; p<0·0001 for all serotypes), and declined by month 30 (54·1 U/mL [38·6-75·7] to 101·6 U/mL [77·6-133·1] vs 21·9 U/mL [18·0-26·6] to 24·9 U/mL [19·0-32·6] in the placebo group; p<0·0001 for all serotypes except serotype 1 [p=0·0006]). Solicited local adverse events were reported more frequently in the VLA15 group (35 [92%, 95% CI 79-97] of 38 participants) than the placebo group (six [32%, 15-54] of 19 participants; p<0·0001) after booster vaccination. There was no significant difference in the frequency of solicited systemic adverse events between groups (20 [59%, 42-74] of 34 participants in the VLA15 group vs six [38%, 18-61] of 16 participants in the placebo group). Related unsolicited adverse events (none severe) were reported by two (5%, 1-17) of 39 participants in the VLA15 group and none (0%, 0-17) of 19 participants in the placebo group. There were no severe solicited local or systemic adverse events or deaths during the study. A booster dose of VLA15 is safe and induces substantial anamnestic immune responses against all six OspA serotypes. As with previously investigated OspA-based Lyme borreliosis vaccines, waning immune responses were observed with VLA15, and annual boosters might therefore be required. Valneva.

Improving HPV Vaccination Uptake Among Adolescents in Low Resource Settings: Sociocultural and Socioeconomic Barriers and Facilitators.

Lower- and middle-income countries (LMICs) are disproportionately impacted by human papillomavirus (HPV) and would benefit from implementing the HPV vaccine. In the context of competing health priorities, utilizing scarce domestic infrastructure and human resources for HPV vaccination remains challenging for many LMICs. Given the high benefits of the HPV vaccine, the World Health Organization (WHO) is now encouraging for all countries, particularly LMICs, to introduce HPV vaccines into their routine immunization programs. Understanding the barriers and facilitators to HPV adolescent vaccine programs in LMICs may help strengthen how LMICs implement HPV vaccine programs, in turn, increasing HPV vaccine acceptance, uptake, and coverage. To identify and assess barriers and facilitators to implementing adolescent HPV vaccination programs in LMICs. This study comprised a review of literature assessing adolescent HPV vaccination in LMICs published after 2020 from a sociocultural perspective. Overall, the findings showed that LMICs should prioritize increasing HPV vaccine availability and HPV vaccine knowledge, particularly focusing on cancer prevention, as knowledge reduces misinformation and increases vaccine acceptance. Evidence suggests that factors promoting HPV vaccine uptake include fostering low vaccine hesitancy, integrating HPV vaccination as a primary school routine vaccination, and vaccinating both genders. A one-dose HPV vaccine may enable many LMICs to increase vaccine acceptance, uptake, and coverage while controlling financial, infrastructure, and human resource costs. As HPV is one of the leading causes of death in many LMICs, implementing the HPV vaccine may be highly beneficial. Cohesive national HPV vaccine buy-in and understanding the success and challenges of prior LMIC HPV vaccine implementation is crucial to developing effective, efficient, and sustainable HPV vaccination programs.

COVID-19 vaccination-induced antibody responses and waning by age and comorbidity status in a large population-based prospective cohort study

BackgroundInformation on the magnitude and duration of antibody levels after COVID-19 vaccination in different groups may be useful for prioritizing of additional vaccinations. MethodsSerum samples were collected every six months in a prospective cohort study among adults in the Netherlands. Geometric mean concentrations (GMCs) of antibodies against the receptor binding domain of the SARS-CoV-2 spike protein were calculated after the primary series, first, and second booster vaccinations. Effects of age (18–59 vs 60–85 years) and medical risk conditions on GMC 2–6 weeks and 21–25 weeks after each vaccination, and on waning during 3–25 weeks after each vaccination, were estimated by linear regression. ResultsWe included 20,640, 15,229 and 8,392 samples collected after primary, first and second booster vaccination, respectively. GMCs at 2–6 and 21–25 weeks after primary series were lower in participants with older age or medical risk conditions. After the first booster, older age was associated with lower GMC at 2–6 weeks and at 21–25 weeks. Waning after the first and second boosters (only 60–85) was not associated with age or medical risk conditions. ConclusionsSince antibody differences by age and medical risk groups have become small with increasing number of doses, other factors such as COVID-19 disease severity rather than antibody levels are useful for prioritization of additional vaccinations.

Reactogenicity of Primary Vaccination with Hexavalent Vaccines in Infants: Mathematical Projections in Four Southeast Asian Countries

Reactogenicity of Primary Vaccination with Hexavalent Vaccines in Infants: Mathematical Projections in Four Southeast Asian Countries

Similar Limited Protection Against Severe Acute Respiratory Syndrome Coronavirus 2 Omicron Infection in Vaccinated Individuals With HIV and Comparable Controls.

Little is known about the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron infection in people with human immunodeficiency virus (HIV; PWH) with vaccine-induced or hybrid immunity. We assessed the incidence of Omicron infection in 209 AGEhIV coronavirus disease 2019 substudy participants with well-controlled HIV on antiretroviral therapy and 280 comparable controls, who had received at least the primary vaccination series. From September 2020 onward, participants were assessed every 6 months for the incidence of SARS-CoV-2 infection, per SARS-CoV-2 nucleocapsid antibody assay or self-reported positive antigen or polymerase chain reaction test. Between 1 January and 31 October 2022, the cumulative incidence of Omicron infection and associated risk factors were estimated using a conditional risk-set Cox proportional hazards model. The cumulative incidence of a first Omicron infection was 58.3% by 31 October 2022, not significantly different between groups. HIV status was not independently associated with acquiring Omicron infection. Former and current smoking, as well as an increased predicted anti-spike immunoglobulin G titer were significantly associated with a lower risk of Omicron infection. The majority of infections were symptomatic, but none required hospitalization. People with well-controlled HIV and controls in our cohort experienced a similarly high proportion of Omicron infections. More booster vaccinations significantly reduced the risk of infection. Clinical Trial Registration. NCT01466582.

Factors predicting primary and booster COVID-19 vaccination in a community sample of African American men and women in the United States Midwest

COVID-19 has disproportionately burdened impoverished minority communities. This study recruited an age- and gender-diverse community sample of 541 Black adults in a United States Midwestern city with large racial health disparities, with the aim of examining factors associated with COVID-19 vaccination. All participants completed measures assessing their COVID-19 vaccination status (unvaccinated, received primary vaccination, or received primary plus booster vaccination) as well as demographic characteristics, socioeconomic factors, health and health system factors, and health behavior theory constructs related to vaccination. In this predominantly low-income sample, 55% of participants had received primary COVID-19 vaccination and 31% of the sample had received a booster dose. Multiple regression analyses established that having primary vaccination was significantly predicted by older age, political identification as Democrat, education beyond high school, barriers to accessing health care, as well as higher trust of vaccine benefits, less preference for natural immunity, stronger social norms favoring vaccination, and perceiving higher levels of collective responsibility. Surprisingly, higher global medical mistrust and difficulty with healthcare access were associated with vaccination. The model explained 76% of the variance in primary COVID-19 vaccination. Having received a COVID-19 booster was predicted by older age, previous COVID-19 infection, higher trust in vaccine benefits, and fewer worries about unforeseen future effects of vaccination. Study findings identified factors associated with COVID-19 vaccine uptake in racial minority communities, and support the benefits of interventions that harness social network supports for vaccination, address community vaccine concerns, and appeal to collective responsibility to promote vaccine uptake.

Age differentially impacts adaptive immune responses induced by adenoviral versus mRNA vaccines against COVID-19.

Adenoviral and mRNA vaccines encoding the viral spike (S) protein have been deployed globally to contain severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Older individuals are particularly vulnerable to severe infection, probably reflecting age-related changes in the immune system, which can also compromise vaccine efficacy. It is nonetheless unclear to what extent different vaccine platforms are impacted by immunosenescence. Here, we evaluated S protein-specific immune responses elicited by vaccination with two doses of BNT162b2 or ChAdOx1-S and subsequently boosted with a single dose of BNT162b2 or mRNA-1273, comparing age-stratified participants with no evidence of previous infection with SARS-CoV-2. We found that aging profoundly compromised S protein-specific IgG titers and further limited S protein-specific CD4+ and CD8+ T cell immunity as a probable function of progressive erosion of the naive lymphocyte pool in individuals vaccinated initially with BNT162b2. Our results demonstrate that primary vaccination with ChAdOx1-S and subsequent boosting with BNT162b2 or mRNA-1273 promotes sustained immunological memory in older adults and potentially confers optimal protection against coronavirus disease 2019.

Effectiveness of mRNA COVID-19 Vaccines as First Booster Doses in England: An Observational Study in OpenSAFELY-TPP.

The UK delivered its first "booster" COVID-19 vaccine doses in September 2021, initially to individuals at high risk of severe disease, then to all adults. The BNT162b2 Pfizer-BioNTech vaccine was used initially, then also Moderna mRNA-1273. With the approval of the National Health Service England, we used routine clinical data to estimate the effectiveness of boosting with BNT162b2 or mRNA-1273 compared with no boosting in eligible adults who had received two primary course vaccine doses. We matched each booster recipient with an unboosted control on factors relating to booster priority status and prior COVID-19 immunization. We adjusted for additional factors in Cox models, estimating hazard ratios up to 182 days (6 months) following booster dose. We estimated hazard ratios overall and within the following periods: 1-14, 15-42, 43-69, 70-97, 98-126, 127-152, and 155-182 days. Outcomes included a positive SARS-CoV-2 test, COVID-19 hospitalization, COVID-19 death, non-COVID-19 death, and fracture. We matched 8,198,643 booster recipients with unboosted controls. Adjusted hazard ratios over 6-month follow-up were: positive SARS-CoV-2 test 0.75 (0.74, 0.75); COVID-19 hospitalization 0.30 (0.29, 0.31); COVID-19 death 0.11 (0.10, 0.14); non-COVID-19 death 0.22 (0.21, 0.23); and fracture 0.77 (0.75, 0.78). Estimated effectiveness of booster vaccines against severe COVID-19-related outcomes peaked during the first 3 months following the booster dose. By 6 months, the cumulative incidence of positive SARS-CoV-2 test was higher in boosted than unboosted individuals. We estimate that COVID-19 booster vaccination, compared with no booster vaccination, provided substantial protection against COVID-19 hospitalization and COVID-19 death but only limited protection against positive SARS-CoV-2 test. Lower rates of fracture in boosted than unboosted individuals may suggest unmeasured confounding. Observational studies should report estimated vaccine effectiveness against nontarget and negative control outcomes.