Reduced antibody acquisition with increasing age following vaccination with BNT162b2: results from a large study performed in the general population aged 12 to 92 years (preprint)

Vaccine-induced protection of the population against severe COVID-19, hospitalization and death is of utmost importance, especially in the elderly. However, limited data are available on humoral immune responses following COVID-19 vaccination in the general population across a broad age range. We performed an integrated analysis of the effect of age, sex and prior SARS-CoV-2 infection on Spike S1-specific (S1) IgG concentrations up to three months post BNT162b2 vaccination. 1,735 persons, eligible for COVID-19 vaccination through the national program, were recruited from the general population (12 to 92 years old). Sixty percent were female and the median vaccination interval was 35 days (interquartile range, IQR: 35-35). All participants had seroconverted to S1 one month after two doses of vaccine. S1 IgG was higher in participants with a history of SARS-CoV-2 infection (median: 4,535 BAU/ml, IQR: 2,341-7,205) compared to infection-naive persons (1,842 BAU/ml, 1,019-3,116) after two doses, p<0.001. In infection-naive persons, linear mixed effects regression showed a strong negative association between age and S1 IgG one month after the first vaccination (p<0.001) across the entire age range. The association was still present after the second vaccination, but less pronounced. Females had higher S1 IgG than males after both the first and second vaccination (p<0.001); although this difference was lower after the second dose. In persons with an infection history, age nor sex was associated with peak S1 IgG. As IgG decreased with age and time since vaccination, older persons may become at risk of infection, especially with escape variants such as Omicron.

SARS-CoV-2 Spike S1-specific IgG kinetic profiles following mRNA- versus vector-based vaccination in the general Dutch population (preprint)

mRNA- and vector-based vaccines are used at a large scale to prevent COVID-19. We compared Spike S1-specific (S1) IgG antibodies after vaccination with mRNA-based (Comirnaty, Spikevax) or vector-based (Janssen, Vaxzevria) vaccines, using samples from a Dutch nationwide cohort. mRNA vaccines induced faster inclines and higher S1 antibodies compared to vector-based vaccines in adults 18-64 years old (n=2,412). For all vaccines, one dose resulted in boosting of S1 antibodies in adults with a history of SARS-CoV-2 infection. For Comirnaty, two to four months following the second dose (n=196), S1 antibodies in adults aged 18-64 years old (436 BAU/mL, interquartile range: 328-891) were less variable and median concentrations higher compared to those in persons [≥]80 years old (366, 177-743), but differences were not statistically significant (p>0.100). Nearly all participants seroconverted following COVID-19 vaccination, including the aging population. These data confirm results from controlled vaccine trials in a general population, including vulnerable groups.