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. 2022 Sep;10(9):e679.
doi: 10.1002/iid3.679.

Impaired immunity and high attack rates caused by SARS-CoV-2 variants among vaccinated long-term care facility residents

Dorothée Obach  1   2 , Anna Solastie  3 , Oona Liedes  3 , Saimi Vara  3 , Eva Krzyżewska-Dudek  4   5 , Luise Brinkmann  4 , Anu Haveri  3 , Charlotte C Hammer  1   2 , Timothée Dub  1 , Seppo Meri  4 , Tobias L Freitag  4 , Outi Lyytikäinen  1 , Merit Melin  3
Affiliations

Impaired immunity and high attack rates caused by SARS-CoV-2 variants among vaccinated long-term care facility residents

Dorothée Obach et al. Immun Inflamm Dis. 2022 Sep.

Abstract

Introduction: Long-term care facilities (LTCF) residents are at high risk for severe coronavirus disease 2019 (COVID-19), and therefore, COVID-19 vaccinations were prioritized for residents and personnel in Finland at the beginning of 2021.

Methods: We investigated COVID-19 outbreaks in two LTCFs, where residents were once or twice vaccinated. After the outbreaks we measured immunoglobulin G (IgG) antibodies to severe acute respiratory syndrome coronavirus 2 spike glycoprotein, neutralizing antibody (NAb) titers, and cell-mediated immunity markers from residents and healthcare workers (HCWs).

Results: In LTFC-1, the outbreak was caused by an Alpha variant (B.1.1.7) and the attack rate (AR) among once vaccinated residents was 23%. In LTCF-2 the outbreak was caused by a Beta variant (B.1.351). Its AR was 47% although all residents had received their second dose 1 month before the outbreak. We observed that vaccination had induced lower IgG concentrations, NAb titers and cell-mediated immune responses in residents compared to HCWs. Only 1/8 residents had NAb to the Beta variant after two vaccine doses.

Conclusions: The vaccinated elderly remain susceptible to breakthrough infections caused by Alpha and Beta variants. The weaker vaccine response in the elderly needs to be addressed in vaccination protocols, while new variants capable of evading vaccine-induced immunity continue to emerge.

Keywords: COVID-19; cell-mediated immunity; elderly; long-term care facility; neutralizing antibodies.

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Conflict of interest statement

The Finnish Institute for Health and Welfare has received research funding for studies not related to COVID‐19 from GlaxoSmithKline Vaccines, in which Merit Melin was an investigator. Tobias L. Freitag is an employee of Rokote Laboratories Finland Oy, that is developing a nasal vaccine against SARS‐CoV‐2. Rokote Laboratories Finland has no role in this study. The other authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
IgG levels to WT SARS‐CoV‐2 spike glycoprotein after vaccination with Comirnaty. (A) Receptor binding domain (RBD) and (B) full‐length spike glycoprotein (SFL) in binding antibody units (BAU)/ml. Dashed lines mark the threshold for positive result per antigen. Statistical significance measured with Wilcoxon rank‐sum test, significance level 0.05. IgG, immunoglobulin G; SARS‐CoV‐2, severe acute respiratory syndrome coronavirus 2.
Figure 2
Figure 2
Neutralizing antibody (NAb) titers to SARS‐CoV‐2 (A) wild‐type (WT), (B) Alpha and (C) Beta variants after vaccination with Comirnaty. Dashed line marks the threshold for a positive NAb result (≥4). Statistical significance measured with Wilcoxon rank‐sum test, significance level 0.05. SARS‐CoV‐2, severe acute respiratory syndrome coronavirus.
Figure 3
Figure 3
Peripheral blood mononuclear cell (PBMC) responses to stimulation with (A) SARS‐CoV‐2 recombinant spike glycoprotein or (B) SARS‐CoV‐2 recombinant nucleoprotein. The secretion of IFN‐γ, perforin‐1 or granzyme B into supernatants was measured after 6 days in infected or noninfected residents and healthcare workers (HCWs,) who all had received two doses of Comirnaty. Cytokine concentrations are presented as stimulation indexes. Dashed line marks the threshold for a positive result (stimulation index ≥3). IFN, interferon; SARS‐CoV‐2, severe acute respiratory syndrome coronavirus.
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