Subjects who have developed SARS-CoV-2 specific IgM-S after vaccination show a longer humoral immunity and a lower frequency of infection

We analysed anti-SARS-CoV-2 spike (S) protein (IgG-S), anti-nucleocapsid IgG (IgG-N) and anti-Spike IgM (IgM-S) in 1872 vaccinees at the first dose (D1; w0), after three weeks at the second dose (D2; w3) at three (w6) and 23 weeks (w29) after D2; 109 subjects where further tested at the booster dose (D3, w44), at three weeks (w47) and six months (w70) after D3. Two-level linear regression models were used to evaluate the differences in IgG-S levels.