Antibody response to SARS-CoV-2 vaccination is extremely vivacious in subjects with previous SARS-CoV-2 infection

Abstract

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic calls for rapid actions, now principally oriented to a world-wide vaccination campaign. In this study we verified if, in individuals with a previous SARS-CoV-2 infection, a single dose of messenger RNA (mRNA) vaccine would be immunologically equivalent to a full vaccine schedule in naïve individuals. Health care workers (184) with a previous SARS-CoV-2 infection were sampled soon before the second dose of vaccine and between 7 and 10 days after the second dose, the last sampling time was applied to SARS-CoV-2 naïve individuals, too. Antibodies against SARS-CoV-2 were measured using Elecsys Anti-SARS-CoV-2 S immunoassay. The study was powered for non-inferiority. We used non parametric tests and Pearson correlation test to perform inferential analysis. After a single vaccine injection, the median titer of specific antibodies in individuals with previous coronavirus disease 2019 was 30.527 U/ml (interquartile range [IQR]: 19.992-39.288) and in subjects with previous SARS-CoV-2 asymptomatic infection was 19.367.5 U/ml (IQR: 14.688-31.353) (p = .032). Both results were far above the median titer in naïve individuals after a full vaccination schedule: 1974.5 U/ml (IQR: 895-3455) (p < .0001). Adverse events after vaccine injection were more frequent after the second dose of vaccine (mean: 0.95; 95% confidence interval [CI]: 0.75-1.14 vs. mean: 1.91; 95% CI: 1.63-2.19) (p < .0001) and in exposed compared to naïve (mean: 1.63; 95% CI: 1.28-1.98 vs. mean: 2.35; 95% CI: 1.87-2.82) (p = .015). In SARS-CoV-2 naturally infected individuals a single mRNA vaccine dose seems sufficient to reach immunity. Modifying current dosing schedules would speed-up vaccination campaigns.

Keywords: COVID-19; SARS-CoV-2; humoral immunity; spike RBD; spike m-RNA vaccine.

Figure 1

Panel A: Specific antibody titers after a full vaccination schedule (two injections) in SARS‐CoV‐2 naïve individuals and a single vaccine injection in subjects with previous exposure to severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) either symptomatic or not. Panel B: Specific antibody titers in subjects with previous exposure to SARS‐CoV‐2 after a single or two doses of vaccine. Panel C: Specific antibody titers in SARS‐CoV‐2 pre‐exposed subjects according to time of infection. Values are differentiated between subjects with previous asymptomatic infection and subjects with previous COVID‐19. COVID‐19, coronavirus disease 2019

Figure 2

Most frequent "AE" observed after vaccine injection