Immunity induced by vaccination and infection, referred to as hybrid immunity, provides better protection against SARS-CoV-2 infections compared to immunity induced by vaccinations alone. To assess the development of hybrid immunity we investigated the induction of Nucleoprotein-specific antibodies in PCR-confirmed infections by Delta or Omicron in vaccinated individuals (n = 520). Eighty-two percent of the participants with a breakthrough infection reached N-seropositivity. N-seropositivity was accompanied by Spike S1 antibody boosting, and independent of vaccination status or virus variant. Following the infection relatively more antibodies to the infecting virus variant were detected. In conclusion, these data show that hybrid immunity through breakthrough infections is hallmarked by Nucleoprotein antibodies and broadening of the Spike antibody repertoire. Exposure to future SARS-CoV-2 variants may therefore continue to maintain and broaden vaccine-induced population immunity.
A large part of the global population has acquired immunity through vaccination, infection or a combination of both i.e. hybrid immunity against SARS-CoV-2 in late 2022 (2022).” href=”https://www.nature.com/articles/s41598-023-45718-8#ref-CR1″ id=”ref-link-section-d30580613e534″>1. Especially Omicron variants have shown their potential to escape vaccine-induced humoral immunity, resulting in many vaccine breakthrough infections and the development of hybrid immunity<a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" title="Eggink, D. et al. Increased risk of infection with SARS-CoV-2 Omicron BA.1 compared with Delta in vaccinated and previously infected individuals, the Netherlands, 22 November 2021 to 19