Seroprevalence of immunoglobulin G antibodies against SARS-CoV-2 in Cyprus

Monitoring the levels of IgG antibodies against the SARS-CoV-2 is important during the coronavirus disease 2019 (COVID-19) pandemic, to plan an adequate and evidence-based public health response. After this study we report that the plasma levels of IgG antibodies against SARS-CoV-2 spike protein were higher in individuals with evidence of prior infection who received at least one dose of either an mRNA-based vaccine (Comirnaty BNT162b2/Pfizer-BioNTech or Spikevax mRNA-1273/Moderna) or an adenoviral-based vaccine (Vaxzervia ChAdOx1 nCoV-19 /Oxford-Astra Zeneca) (n = 39) compared to i) unvaccinated individuals with evidence of prior infection with SARS-CoV-2 (n = 109) and ii) individuals without evidence of prior infection with SARS-CoV-2 who received one or two doses of one of the aforementioned vaccines (n = 342). Our analysis also revealed that regardless of the vaccine technology (mRNA-based and adenoviral vector-based) two doses achieved high antiSARS-CoV-2 IgG responses. Our results indicate that vaccine-induced responses lead to higher levels of IgG antibodies compared to those produced following infection with the virus. Additionally, in agreement with previous studies, our results suggest that among individuals previously infected with SARS-CoV-2, even a single dose of a vaccine is adequate to elicit high levels of antibody response.

Automated summary

Monitoring IgG antibody levels against SARS-CoV-2 is crucial during the COVID-19 pandemic. A study found that individuals with evidence of prior infection who received mRNA or adenoviral vaccines had higher levels of IgG antibodies against the spike protein compared to unvaccinated individuals with prior infection or individuals without prior infection who received vaccines. Regardless of the vaccine technology, two doses produced strong anti-SARS-CoV-2 IgG responses. Results also indicated that even a single dose of vaccine is sufficient to elicit high levels of antibody response in individuals previously infected with SARS-CoV-2.