Immune Response 5–7 Months after Vaccination against SARS-CoV-2 in Elderly Nursing Home Residents in the Czech Republic: Comparison of Three Vaccines

Abstract

Background and Aims: Elderly nursing home residents are especially prone to a severe course of SARS-CoV-2 infection. In this study, we aimed to investigate the complex immune response after vaccination depending on the convalescence status and vaccine. Methods: Sampling took place in September–October 2021. IgG antibodies against spike protein and nucleocapsid protein, the titer of virus neutralization antibodies against delta and (on a subset of patients) omicron, and cellular immunity (interferon-gamma release assay) were tested in nursing home residents vaccinated with Pfizer, Moderna (both 30–31 weeks after the completion of vaccination), or AstraZeneca (23 weeks) vaccines. The prevalence with 95% confidence intervals (CI) was evaluated in Stata version 17. Results: 95.2% (95% CI: 92.5–97.1%) of the 375 participants had positive results of anti-S IgG, 92.8% (95% CI: 89.7–95.2%) were positive in virus neutralization assay against delta, and 89.0% (95% CI: 84.5–92.5%) in the interferon-gamma-releasing assay detecting cellular immunity. Results of the virus neutralization assay against omicron correlated with those against delta but the neutralization capacity was reduced by about half. As expected, the worst results were found for the AstraZeneca vaccine, although the vaccination-to-test period was the shortest for this vaccine. All immune parameters were significantly higher in convalescent residents than in naive residents after vaccination. No case of COVID-19 occurred during the vaccination-to-test period. Conclusions: A high immune response, especially among vaccinated convalescents (i.e., residents with hybrid immunity), was found in elderly nursing home residents 5–7 months after vaccination against SARS-CoV-2. In view of this, it appears that such residents are much better protected from COVID-19 than those who are only vaccinated and the matter of individual approach to the booster dose in such individuals should be further discussed.

Effectiveness of BNT162b2 mRNA vaccine third doses and previous infection in protecting against SARS-CoV-2 infections during the Delta and Omicron variant waves; the UK SIREN cohort study September 2021 to February 2022

“…Most notable are differences with neutralising antibody (nAb) titres and breadth of neutralisation with hybrid immunity compared to vaccine or infection induced immunity. [28][29][30][31][32][33][34] There are other immunological differences between the groups, including in tissue-resident memory T-cells, and the mucosal immune system, [34][35][36][37] The key strengths of our study include the size of our cohort undergoing frequent PCR testing independent of disease status, giving us confidence that most infections were detected. Having monitored our well-characterised cohort for infections and vaccination since June 2020, we have a valuable history of antigenic exposures for all our participants, enabling analysis of time since infection.…”

Humoral immunity induced by mRNA COVID-19 vaccines in Nursing Home Residents previously infected with SARS-CoV-2

“…Most important, recent studies in NH residents with or without a previous history of SARS-CoV-2 infection, have shown higher antibody response ensured by the hybrid immunity effect. Martinek and colleagues showed that 5–7 months after vaccination immune parameters were significantly higher in convalescent residents than in naive residents after vaccination [ 18 ]. Similar findings were described by Jeulin et al who showed that NH residents with a history of SARS-CoV-2 infection have a clear advantage in the magnitude and duration anti-S IgG titers following the 2nd dose [ 19 ].…”