Design
A longitudinal study was carried out in NHs having faced a COVID-19 outbreak in 2020. Firstly, we compared N- and S-protein IgG levels three weeks after a single BNT162b2 jab in residents without prior COVID-19 (with repeated negative RT-PCR and negative N-protein IgG measured 3 weeks after the jab) and in residents with prior COVID-19 (confirmed either by a positive RT-PCR or by detectable N-protein IgG). Two periods were considered - the past 9 to 12 months (older infections) and the past 3 to 7 months (newer infections) - corresponding to the first and second waves of the epidemic in our region.
Secondly, S-protein levels were compared six weeks after a second BNT162b2 jab in residents with or without prior COVID-19.