Antibody response induced by the BNT162b2 mRNA COVID-19 vaccine in a cohort of health-care workers, with or without prior SARS-CoV-2 infection: a prospective study

Abstract

Objectives We assessed the antibody response to BNT162b2 mRNA COVID-19 vaccine in a cohort of health care workers (HCW), comparing subjects with previous SARS-CoV-2 infection and naïve subjects. Methods HCW were tested at T0 (day of first dose), T1 (day of second dose), and T2 (2-3 weeks after) for IgG anti nucleocapside protein, IgM anti spike protein and IgG anti receptor binding domain (IgG-RBD-S). The antibody response was compared between 4 main groups: A) Subjects with previous infection and positive antibodies at baseline; B) subjects with same history but negative antibodies; C) subjects with no infection history but positive antibodies; D) naïve subjects. Repeated measures analysis was used to compare results over time points. Results 1,935 HCW were included. Median IgG-RBD-S titre was significantly higher for group A (232 subjects) than for group B (56 subjects) both at T1 (A: 22,763 AU/mL, IQR 14,222-37,204; B: 1,373 AU/mL, IQR 783-3,078, p=0.0003) and T2 (A: 30,765 AU/mL, IQR 19,841-42,813; B:13,171 AU/mL, IQR 2,324-22,688, p=0.0038) and for group D (1563 subjects): 796 AU/mL, IQR 379-1,510 at T1; 15,494 AU/mL, IQR 9,122-23,916 at T2, p<0.0001 both timepoints. T1 values of group A were also significantly higher than T2 values of group D (p<0.0001). Presence of symptoms, younger age and female gender were associated with stronger antibody response. HCW infected in March showed a significantly stronger response (T1: 35,324 AU/mL, IQR 22,003-44,531; T2: 37,648 AU/mL, IQR 27,088-50,451) than those infected in November (T1: 18,499 AU/mL, IQR 11,492-27,283; T2: 23,210 AU/mL, IQR 18,074-36,086): p<0.0001, both timepoints. Conclusions Subjects with past COVID-19 infection had a strong antibody response after one single vaccine shot. A single dose might be sufficient for this group, regardless the time elapsed since infection, however the clinical correlation with antibody response needs to be studied.

Immunity after COVID-19 and vaccination: follow-up study over 1 year among medical personnel

“…This reassuring finding stands in contrast to a recent publication from Italy that describes lower antibody levels in fully vaccinated COVID-19-naïve individuals [ 26 ]. Other groups showed that a second booster dose given after the first booster vaccination to patients with previous COVID-19 did not increase antibody levels further [ 25 , 27 ].…”

Response to BNT162b2 mRNA COVID-19 vaccine among healthcare workers in Italy: a 3-month follow-up

“…More interestingly, we found that vaccine-induced antibody level was significantly high after 2 weeks from the single dose of SARS-CoV-2 mRNA vaccine in HCWs with preexisting immunity. Several data showed that one dose of the BNT162b2 vaccine (as well as other COVID-19 vaccines) maximizes the cellular and humoral immune response to S1 spike protein in subjects with previous SARS-CoV-2 infection and our results corroborate the hypothesis that previous SARS-CoV-2 infection may be considered an analogous to immune priming [ 6 , 7 ].…”

Antibody responses induced by the BNT162b2 mRNA COVID-19 vaccine in healthcare workers in a single community hospital in Japan

“…Antibody titers were significantly higher in women and in younger participants even more than three months after the second dose of the vaccine. Several studies have indicated that sex and age are associated with antibody responses [ [11] , [12] , [13] ], and the findings of this study are consistent with these reports. Kageyama et al reported that the use of medications for allergies had a correlation with lower antibody titers [ 13 ], although the results from this study showed no association.…”