SARS-CoV-2-antibody response in health care workers after vaccination or natural infection in a longitudinal observational study

BackgroundFollowing a year of development, several vaccines have been approved to contain the global COVID-19 pandemic. Real world comparative data on immune response following vaccination or natural infection are rare.MethodsWe conducted a longitudinal observational study in employees at a secondary care hospital affected by the COVID-19 pandemic. Comparisons were made about the presence of anti-SARS-CoV-2 immunglobulin G (IgG) antibody ratio after natural infection, or vaccination with one or two doses of BioNTech/Pfizer (BNT162b2), or one dose of AstraZenca (Vaxzevria) vaccine.ResultsWe found a 100% humoral response rate in participants after 2 doses of BNT162b2 vaccine. The antibody ratio in participants with one dose BNT162b2 and Vaxzevria did not differ significantly to those with previous PCR-confirmed infection, whereas this was significantly lower in comparison to two doses of BioNTech/Pfizer. We could not identify a correlation with previous comorbidities, obesity or age within this study. Smoking showed a negative effect on the antibody response (p = 0.006)ConclusionOur data provide an overview about humoral immune response after natural SARS-CoV-2 infection or following vaccination, and supports the usage of booster vaccinations, especially in patients after a natural SARS-CoV-2 infection.     

COVID-19 vaccine uptake,effectiveness, and waning in 82,959 health care workers: A national prospective cohort study in Wales

BackgroundWhile population estimates suggest high vaccine effectiveness against SARS-CoV-2 infection, the protection for health care workers, who are at higher risk of SARS-CoV-2 exposure, is less understood.MethodsWe conducted a national cohort study of health care workers in Wales (UK) from 7 December 2020 to 30 September 2021. We examined uptake of any COVID-19 vaccine, and the effectiveness of BNT162b2 mRNA (Pfizer-BioNTech) against polymerase chain reaction (PCR) confirmed SARS-CoV-2 infection. We used linked and routinely collected national-scale data within the SAIL Databank. Data were available on 82,959 health care workers in Wales, with exposure extending to 26 weeks after second doses.ResultsOverall vaccine uptake was high (90%), with most health care workers receiving the BNT162b2 vaccine (79%). Vaccine uptake differed by age, staff role, socioeconomic status; those aged 50–59 and 60+ years old were 1.6 times more likely to get vaccinated than those aged 16–29. Medical and dental staff, and Allied Health Practitioners were 1.5 and 1.1 times more likely to get vaccinated, compared to nursing and midwifery staff. The effectiveness of the BNT162b2 vaccine was found to be strong and consistent across the characteristics considered; 52% three to six weeks after first dose, 86% from two weeks after second dose, though this declined to 53% from 22 weeks after the second dose.ConclusionsWith some variation in rate of uptake, those who were vaccinated had a reduced risk of PCR-confirmed SARS-CoV-2 infection, compared to those unvaccinated. Second dose has provided stronger protection for longer than first dose but our study is consistent with waning from seven weeks onwards.     

Safety and effectiveness of BNT162b2 mRNA Covid-19 vaccine in adolescents

In South Korea, all 12th grade students (highs school seniors) were offered BNT162b2 vaccine starting July 19, 2021; while 10^th–11th grade students were not eligible. We conducted a nationwide retrospective cohort study by to determine the safety and effectiveness of BNT162b2 mRNA Covid-19 vaccine in adolescents against SARS-CoV-2 infection. Among 444,313 persons who received the first dose of vaccine, reporting rate for myocarditis and/or pericarditis was 1.8 per 100,000 (95% C.I. 0.8–3.5) among first-dose recipients and 4.3 per 100,000 (95% C.I. 2.6–6.7) in second-dose recipients. Vaccine effectiveness against symptomatic/asymptomatic SARS-CoV-2 infection 14 days post-first dose vaccination was 91.1% (95% C.I. 89.6–92.5), and 14 days post-second dose was 99.1% (95% C.I. 98.5–99.5). In this retrospective cohort study, BNT162b2 vaccination was safe and was associated with a significantly lower risk of SARS-CoV-2 infection, suggesting that vaccination in adolescent may reduce the burden of Covid-19.     

Impact of national Covid-19 vaccination Campaign,South Korea

BackgroundWe evaluate the overall effectiveness of the nationwide vaccination campaign using ChAdOx1 nCoV-19, BNT162b2, mRNA-1273, and Ad26.COV2.S vaccines in preventing Covid-19 in South Korea.MethodsThe National Surveillance System with the National Immunization Registry were linked to form a large-linked database for assessment. Age-adjusted incidence of SARS-CoV-2 infection, severe disease, and death by vaccination status are calculated. Weekly vaccine effectiveness was calculated based on incidence rate ratio (IRR) between fully-vaccinated and unvaccinated persons, as: IRR = incidence rate of vaccinated / incidence rate of unvaccinated. We estimate the cumulative SARS-CoV-2 outcome overtime comparing the observed case with predicted cases without vaccination.ResultsAge-adjusted incidence in unvaccinated persons (5.69 per 100,000 person-day) was 2.7 times the rate in fully vaccinated (2.13 per 100,000 person-day) persons, resulting effectiveness against SARS-CoV-2 infection of 63%. Vaccine effectiveness against severe disease and death were 93% and 95%, respectively. Between March and October 2021, estimated Covid-19 related outcomes averted by vaccinations were: 46,508 infections, 3,424 severe diseases, and 718 deaths.ConclusionsWe found significant protection for national Covid-19 vaccination campaign against Covid-19 severe disease, and death in target populations, but there was an unexpected decreased protection against SARS-CoV-2 infection, highlighting the importance of continued surveillance and assessment.     

Neutralizing antibody responses in healthcare personnel after three doses of mRNA BNT162b2 vaccine and association with baseline characteristics and past SARS-CoV-2 infection

AimTo estimate neutralizing antibody (NAb) immunity against SARS-CoV-2 in 739 healthcare personnel (HCP) vaccinated with three doses of BNT162b2 mRNA vaccine.MethodsSerum samples were collected at 3, 6, and 9 months after the second vaccine dose and at 7–55 days after the third dose. Samples were tested for NAbs against SARS-CoV-2 receptor binding domain.ResultsThe mean inhibition rates at 3, 6, and 9 months after the second dose were 86.33%, 73.38%, and 61.18%, and increased to 95.57% after the booster dose. Younger HCP and HCP with past SARS-CoV-2 infection had higher inhibition rates while there was an inverse correlation between NAb levels and comorbidities or tobacco use (p-values < 0.001). Increased NAb titers were also noticed in women (p-value = 0.033), especially at the end of the 9-month study period.ConclusionNAb levels increased considerably after a booster mRNA vaccine dose. Host factors and past SARS-CoV-2 infection influence NAb titers.     

Immunological responses and adverse reactions of the heterologous second booster dose of BNT162b2 after two-dose CoronaVac for COVID-19 vaccination in healthcare workers of Faculty of Medicine,Naresuan University

BackgroundThe first COVID-19 vaccination campaign in Thailand began in April 2020, with healthcare workers receiving two doses of inactivated COVID-19 vaccine (CoronaVac). However, the emergence of the delta and omicron variants raised concerns about vaccine effectiveness. The Thai Ministry of Public Health provided the first booster dose (third dose) and second booster dose (fourth dose) of the mRNA vaccine (BNT162b2) for healthcare workers. This study investigated the immunity and adverse reactions elicited by a heterologous second booster dose of BNT162b2 after a two-dose CoronaVac vaccination for COVID-19 in healthcare workers of the Faculty of Medicine, Naresuan University.MethodsIgG titres against the SARS-CoV-2-spike protein were measured four and 24 weeks after the second booster dose of BNT162b2 in the study participants. Adverse reactions were recorded during the first three days, four weeks and 24 weeks after the second booster dose of BNT162b2.ResultsIgG against the SARS-CoV-2-spike protein was positive (>10 U/ml) in 246 of 247 participants (99.6 %) at both four and 24 weeks after the second booster dose of BNT162b2. The median specific IgG titres at four and 24 weeks after the second booster dose of BNT162b2 were 299 U/ml (min: 2, max: 29,161) and 104 U/ml (min: 1, max: 17,920), respectively. The median IgG level declined significantly 24 weeks after the second booster dose of the BNT162b2 vaccine. Of the 247 participants, 179 (72.5 %) experienced adverse reactions in the first three days after the second booster dose of BNT162b2. Myalgia, fever, headache, injection site pain and fatigue were the most common adverse reactions.ConclusionThis study demonstrated that a heterologous second booster dose of BNT162b2 after two doses of CoronaVac induced elevated IgG against the SARS-CoV-2-spike protein and caused minor adverse reactions in healthcare workers of the Faculty of Medicine, Naresuan University.This study was registered as Thailand Clinical Trials No. TCTR20221112001.     

Effectiveness of Covid-19 vaccines against symptomatic and asymptomatic SARS-CoV-2 infections in an urgent care setting

BackgroundIt is critical to monitor changes in vaccine effectiveness against COVID-19 outcomes for various vaccine products in different population subgroups.MethodsWe conducted a retrospective study in patients ≥12 years who underwent testing for SARS-CoV-2 virus from April 14 through October 25, 2021, at urgent care centers in the New York metropolitan area. Patients self-reported vaccination status at the time of testing. We used a test-negative design to estimate vaccine effectiveness (VE) by comparing odds of a positive test for SARS-CoV-2 infection among vaccinated (n = 474,805), partially vaccinated (n = 87,834), and unvaccinated (n = 369,333) patients, adjusted for demographic factors and calendar time.ResultsVE against symptomatic infection after 2 doses of mRNA vaccine was 96% (95% Confidence Interval: 95%, 97%) in the pre-delta period and reduced to 79% (95% CI: 77%, 81%) in the delta period. In the delta period, VE for 12–15-year-olds (85%; [95% CI: 81%, 88%]) was higher compared to older age groups (<65% for all other age groups). VE estimates did not differ by sex and race/ethnicity. VE against symptomatic infection was the highest for individuals with a prior infection followed by full vaccination. VE against symptomatic infection after the 2-dose mRNA-1273 vaccine (82% [95% CI: 80%, 84%]) was higher compared to the BNT162b2 vaccine (76% [95% CI: 74%, 78%]) in the delta period. VE after 1-dose of the Ad26.COV2.S vaccine was the lowest compared to other vaccines (19% [95% CI: 15%, 23%]) in the delta period.ConclusionsVE against infection after two doses of the mRNA vaccines was high initially, but significantly reduced against the delta variant for both FDA-approved vaccines.     

A heterologous AZD1222 priming and BNT162b2 boosting regimen more efficiently elicits neutralizing antibodies,but not memory T cells,than the homologous BNT162b2 regimen

BackgroundComparative analyses of SARS-CoV-2-specific immune responses elicited by diverse prime-boost regimens are required to establish efficient regimens for the control of COVID-19.MethodIn this prospective observational cohort study, spike-specific immunoglobulin G (IgG) and neutralizing antibodies (nAbs) alongside spike-specific T-cell responses in age-matched groups of homologous BNT162b2/BNT162b2 or AZD1222/AZD1222 vaccination, heterologous AZD1222/BNT162b2 vaccination, and prior wild-type SARS-CoV-2 infection/vaccination were evaluated.ResultsPeak immune responses were achieved after the second vaccine dose in the naïve vaccinated groups and after the first dose in the prior infection/vaccination group. Peak titers of anti-spike IgG and nAb were significantly higher in the AZD1222/BNT162b2 vaccination and prior infection/vaccination groups than in the BNT162b2/BNT162b2 or AZD1222/AZD1222 groups. However, the frequency of interferon-γ-producing CD4⁺ T cells was highest in the BNT162b2/BNT162b2 vaccination group. Similar results were observed in the analysis of polyfunctional T cells. When nAb and CD4⁺ T-cell responses against the Delta variant were analyzed, the prior infection/vaccination group exhibited higher responses than the groups of other homologous or heterologous vaccination regimens.ConclusionnAbs are efficiently elicited by heterologous AZD1222/BNT162b2 vaccination, as well as prior infection/vaccination, whereas spike-specific CD4⁺ T-cell responses are efficiently elicited by homologous BNT162b2 vaccination. Variant-recognizing immunity is more efficiently generated by prior infection/vaccination than the other homologous or heterologous vaccination regimens.     

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

ObjectivesTo identify factors that contribute to protection from infection with the Omicron variant of SARS-CoV-2 in older adults in nursing and retirement homes.DesignLongitudinal cohort study with retrospective analysis of infection risk.Setting and Participants997 residents of nursing and retirement homes from Ontario, Canada, in the COVID in LTC study.MethodsResidents 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.ResultsIn 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 3 months prior to beginning of the Omicron wave [0.52, (0.27‒0.99)].Conclusions and ImplicationsVaccine 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.     

Safety and efficacy of COVID-19 prime-boost vaccinations: Homologous BBIBP-CorV versus heterologous BNT162b2 boosters in BBIBP-CorV-primed individuals

BackgroundBooster vaccine doses against SARS-CoV-2 have been advocated to address evidence of waning immunity, breakthrough infection, and the emergence of immune-evasive variants. A heterologous prime-boost vaccine strategy may offer advantages over a homologous approach, but the safety and efficacy of this approach with the mRNA vaccine BNT162b2 (BNT: Pfizer) and inactivated BBIBP-CorV (BBIBT: Sinopharm) vaccines have not been studied.MethodsWe conducted a non-randomized, non-blinded phase II observational community trial across Bahrain, investigating the reactogenic and immunogenic response of participants who had previously received two doses of BBIBP, followed by a third booster dose of either BBIBP (homologous booster) or BNT (heterologous booster). Immunogenicity through serological status was determined at baseline and on the following 8th week. Reactogenicity data (safety and adverse events) were collected throughout study period, in addition to participant-led electronic journaling.Results305 participants (152 BBIBP and 153 BNT booster) were enrolled in the study, with 246 (127 BBIBP and 119 BNT booster) included in the final analysis. There was a significant increase in anti-SARS-CoV-2 antibody levels post booster administration in both groups; however, the heterologous BNT arm demonstrated a significantly larger mean increase in the level of spike (S) antigen-specific antibodies (32.7-fold increase versus 2.6, p < 0.0001) and sVNT neutralising antibodies (3.4-fold increase versus 1.8, p < 0.0001), whereas the homologous arm demonstrated a significant increase in the levels of nucleocapsid (N) antigen-specific antibodies (3.8-fold increase versus none). Non-serious adverse events (injection site pain, fever, and fatigue) were more commonly reported in the heterologous arm, but no serious adverse events occurred.ConclusionHeterologous prime-boost vaccination with the mRNA BNT162b2 (Pfizer) vaccine in those who had received two doses of inactivated virus BBIBP-CorV (Sinopharm) vaccine demonstrated a more robust immune response against SARS-CoV-2 than the homologous BBIBP booster and appears safe and well tolerated.Clinical Trial Registry Number (ClinicalTrials.gov): NCT04993560.     

Kinetics of SARS-CoV-2 anti-S IgG after BNT162b2 vaccination

Deployment of the BNT162b2 mRNA Covid-19 Vaccine in Israel began in December 2020.This is a retrospective analysis of serological data, showing SARS-CoV-2 anti-S IgG kinetics in 116 Israeli health care workers receiving BNT162b2.Sero-conversion occurred in 14 days in all study participants, with IgG levels peaking approximately 30 days after initiation of the vaccination series.A statistically significant difference was observed in IgG levels between subjects younger than 50 years and older participants, although in all cases, IgG levels were well above the level considered reactive by the test's manufacturer.The importance of this difference needs to be studied further, but a potential difference in vaccine efficacy and vaccine effect length could possibly be present between these two groups.     

Induced humoral immunity of different types of vaccines against most common variants of SARS-CoV-2 in Egypt prior to Omicron outbreak

The diversity of SARS-CoV-2 continues to lead to the emergence of new SARS-CoV-2 variants. SARS-CoV-2 antibody assays are crucial in managing the COVID-19 pandemic by determining the neutralizing antibody response. This study aims to investigate vaccine-induced antibodies against most common variants of SARS-CoV-2 in Egypt. Sera samples were collected from vaccinated participants and neutralizing activity against the SARS-CoV-2 variants was determined using microneutralization assay. Our results show that the BNT162b2 (Pfizer-BioNTech), ChAdOx1 nCov-19 (AstraZeneca), and Ad26.COV2.S COVID-19 (Janssen) vaccines elicited neutralizing antibody responses more than the BBIBP-CorV vaccine (Sinopharm) against B.1, C.36.3, and AY.32 (Delta) variants. While vaccines remain highly effective in managing the COVID-19 pandemic, ongoing monitoring of vaccine effectiveness is needed.     

Humoral immune response characterization of heterologous prime-boost vaccination with CoronaVac and BNT162b2

BackgroundVaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has proven to be a successful strategy for prevent severe infections. CoronaVac and BNT162b2 are the most used vaccines worldwide, but their use in heterologous vaccination schedules is still subjected to evaluation.MethodsFifty healthy individuals who received heterologous prime-boost vaccination with CoronaVac and BNT162b2 were enrolled in a post-vaccination serological follow-up longitudinal prospective study. We evaluated specific serum anti-receptor binding domain (RBD) IgG antibody levels, and their capacity to block RBD-ACE2 interaction with a surrogate neutralization assay. In 20 participants, we assessed antibody binding kinetics by surface plasmon resonance, and Fc-mediated functions by ADCC and ADCP reporter assays.ResultsOur baseline seronegative cohort, displayed seroconversion after two doses of CoronaVac and an important decrease in serum anti-RBD IgG antibodies levels 80 days post-second dose. These levels increased significantly early after the third dose with BNT162b2, but 73 days after the booster we found a new fall. Immunoglobulin functionalities showed a similar behavior.ConclusionsThe heterologous prime-boost vaccination with CoronaVac and BNT162b2 generated an impressive increase in serum anti-RBD specific antibody levels followed by a drop. Nevertheless, these titers remained well above those found in individuals only vaccinated with CoronaVac in the same elapsed time. Serum IgG levels showed high correlation with antibody binding analysis, their capacity to block RBD-ACE2 interaction, and Fc-effectors mechanisms. Our work sheds light on the humoral immune response to heterologous vaccination with CoronaVac and BNT162b2, to define a post-vaccination correlate of protection against SARS-CoV-2 infection and to discuss the scheduling of future vaccine boosters in general population.     

BNT162b2 mRNA COVID-19 against symptomatic Omicron infection following a mass vaccination campaign in southern Brazil: A prospective test-negative design study

BackgroundEvidence regarding effectiveness of BNT162b2 mRNA COVID-19 vaccine against Omicron in Latin America is limited. We estimated BNT162b2 effectiveness against symptomatic COVID-19 in Brazil when Omicron was predominant.MethodsThis prospective test-negative, case-control study was conducted in Toledo, Brazil, following a mass COVID-19 vaccination with BNT162b2. Patients were included if they were aged ≥12 years, sought care for acute respiratory symptoms in the public health system between November 3, 2021 and June 20, 2022, and were tested for SARS-CoV-2 using RT-PCR. In the primary analysis, we determined the effectiveness of two doses of BNT162b2 against symptomatic COVID-19.ResultsA total of 4,574 were enrolled; of these, 1,758 patients (586 cases and 1,172 controls) were included in the primary analysis. Mean age was 27.7 years, 53.8 % were women, and 90.1 % had a Charlson comorbidity index of zero. Omicron accounted for >97 % of all identified SARS-CoV-2 variants, with BA.1 and BA.2 accounting for 84.3 % and 12.6 %, respectively. Overall adjusted estimate of two-dose vaccine effectiveness against symptomatic COVID-19 was 46.7 % (95 %CI, 19.9 %–64.6 %) after a median time between the second dose and the beginning of COVID-19 symptoms of 94 days (IQR, 60–139 days). Effectiveness waned from 77.7 % at 7–29 days after receipt of a second dose to <30 % (non-significant) after ≥120 days.ConclusionIn a relatively young and healthy Brazilian population, two doses of BNT162b2 provided protection against symptomatic Omicron infection. However, this protection waned significantly over time, underscoring the need for boosting with variant-adapted vaccines in this population prior to waves of disease activity.Trial registration number: ClinicalTrials.gov number, NCT05052307 (https://clinicaltrials.gov/ct2/show/NCT05052307).     

Vaccine Effectiveness,School Reopening,and Risk of Omicron Infection Among Adolescents Aged 12–17 Years

PurposeThe BNT162b2 (Pfizer-BioNTech) is approved for adolescents aged 12–17 years. We estimated BNT162b2 vaccine effectiveness (VE) and a booster dose effectiveness in adolescents aged 12–17 years and the impact of opening schools and the Omicron variant on risk of SARS-CoV-2 infection in adolescents.MethodsWe used logistic regression with a test-negative design controlling for gender and race to estimate BNT162b2 VE and the effectiveness of a booster dose in adolescents aged 12–17 years. To evaluate the effect of school opening on Omicron transmission, we used Cox proportional hazards regression to compare adolescents to a reference group of adults aged 22–33 or aged 65+ years, investigating whether risk for adolescents increased relative to the reference group after school opened.ResultsWe found that adolescents who received two BNT162b2 doses had significant protection against Omicron infection in the first three months following their second dose (VE = 54.5%, confidence interval [CI]: [17.8%–76.9%], p = .014) but no protection afterwards. Receiving a booster dose was associated with lower risk of infection (odds ratio = 0.48, CI: [0.33–0.69], p < .0001) and restored efficacy to a similar level (VE = 56.3%, CI: [36.5%–70.6%], p < .0001). We observed a statistically significant increase (p = .04) in adolescent infection risk relative to adults in the period of Omicron predominance.DiscussionThe BNT162b2 vaccine is effective at preventing SARS-CoV-2 infection in adolescents but immunity against Omicron wanes rapidly and booster doses are needed to retain protection. More research is needed to determine the effect of school reopening on spread in the Omicron-dominant period.     

Cohort study of Covid-19 vaccine effectiveness among healthcare workers in Finland,December 2020 - October 2021

Recently, Covid-19 vaccine effectiveness has decreased especially against mild disease due to emergence of the Delta variant and waning protection. In this register-based study among healthcare workers in Finland, the vaccine effectiveness of two-dose mRNA vaccine series against SARS-CoV-2 infection decreased from 82% (95% CI 79–85%) 14–90 days after vaccination to 53% (43–62%) after 6 months. Similar trend was observed for other series. Waning was not observed against Covid-19 hospitalization. These results facilitate decision-making of booster doses for healthcare workers.     

T-Cell Mediated Response after Primary and Booster SARS-CoV-2 Messenger RNA Vaccination in Nursing Home Residents

ObjectivesNursing home (NH) residents have been significantly affected by the coronavirus disease 2019 (COVID-19) pandemic. Studies addressing the immune responses induced by COVID-19 vaccines in NH residents have documented a good postvaccination antibody response and the beneficial effect of a third booster vaccine dose. Less is known about vaccine-induced activation of cell-mediated immune response in frail older individuals in the long term. The aim of the present study is to monitor messenger RNA SARS-CoV-2 vaccine-induced T-cell responses in a sample of Italian NH residents who received primary vaccine series and a third booster dose and to assess the interaction between T-cell responses and humoral immunity.DesignLongitudinal cohort study.Setting and ParticipantsThirty-four residents vaccinated with BNT162b2 messenger RNA SARS-CoV-2 vaccine between February and April 2021 and who received a third BNT162b2 booster dose between October and November 2021 were assessed for vaccine-induced immunity 6 (prebooster) and 12 (postbooster) months after the first BNT162b2 vaccine dose.MethodsPre- and postbooster cell-mediated immunity was assessed by intracellular cytokine staining of peripheral blood mononuclear cells stimulated in vitro with peptides covering the immunodominant sequence of SARS-CoV-2 spike protein. The simultaneous production of interferon-γ, tumor necrosis factor-α, and interleukin-2 was measured. Humoral immunity was assessed in parallel by measuring serum concentration of antitrimeric spike IgG antibodies.ResultsBefore the booster vaccination, 31 out of 34 NH residents had a positive cell-mediated immunity response to spike. Postbooster, 28 out of 34 had a positive response. Residents without a previous history of SARS-CoV-2 infection, who had a lower response prior the booster administration, showed a greater increase of T-cell responses after the vaccine booster dose. Humoral and cell-mediated immunity were, in part, correlated but only before booster vaccine administration.Conclusions and ImplicationsThe administration of the booster vaccine dose restored spike-specific T-cell responses in SARS-CoV-2 naïve residents who responded poorly to the first immunization, while a previous SARS-CoV-2 infection had an impact on the magnitude of vaccine-induced cell-mediated immunity at earlier time points. Our findings imply the need for a continuous monitoring of the immune status of frail NH residents to adapt future SARS-CoV-2 vaccination strategies.     

Comparative effectiveness of four COVID-19 vaccines,BNT162b2 mRNA,mRNA-1273, ChAdOx1 nCov-19 and NVX-CoV2373 against SARS-CoV-2 B.1.1.529 (Omicron) infection

BackgroundThere is limited data directly comparing the effectiveness of different COVID-19 vaccines.MethodsWe compared rates of SARS-CoV-2 Omicron BA.1/2 infection during March to May 2022 in Australian adults who had received one of four COVID-19 vaccines in the last 14–63 days as either a primary course or a booster dose using Cox proportional hazards models adjusting for age and other characteristics.ResultsAs a primary course, over 2318 person-years and 1033 infections, compared to recipients of BNT162b2 mRNA vaccine, adjusted hazard ratios for SARS-CoV-2 infection were 1.03 (95%CI 0.82–1.30), 1.19 (0.95–1.49), 1.70 (1.46–1.97) for respectively mRNA-1273, ChAdOx-1 nCov-19 and NVX-CoV2373. For the booster dose, over 154,984 person-years and 93,580 infections the respective adjusted hazard ratios compared to BNT162b2 mRNA vaccine were 1.02 (95%CI 1.00–1.04), 1.20 (1.10–1.32), 1.39 (1.20–1.60).ConclusionsOur findings suggest relatively higher effectiveness of ancestral strain mRNA vaccines against SARS-CoV-2 Omicron infection than viral vector and protein subunit vaccines and provide clinical confirmation of immunological data on differences in COVID-19 vaccine performance.