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. 2021 Nov;83(5):559-564.
doi: 10.1016/j.jinf.2021.08.031. Epub 2021 Aug 23.

Immunogenicity of mRNA-1273 COVID vaccine after 6 months surveillance in health care workers; a third dose is necessary

Marie Tré-Hardy  1 , Roberto Cupaiolo  2 , Alain Wilmet  2 , Thomas Antoine-Moussiaux  3 , Andrea Della Vecchia  3 , Alexandra Horeanga  3 , Emmanuelle Papleux  4 , Marc Vekemans  3 , Ingrid Beukinga  2 , Laurent Blairon  2
Affiliations

Immunogenicity of mRNA-1273 COVID vaccine after 6 months surveillance in health care workers; a third dose is necessary

Marie Tré-Hardy et al. J Infect. 2021 Nov.

Abstract

Objectives: Scarce data are currently available on the kinetics of antibodies after vaccination with mRNA vaccines as a whole and, with mRNA-1273, in particular. We report here an ad-interim analysis of data obtained after a 6-month follow-up in a cohort of healthcare workers (HCWs) who received the mRNA-1273 vaccine. These new data provide more insight into whether and in whom a 3rd dose could be necessary.

Methods: Our study compared the anti-S antibody kinetics at 2 weeks (T1), 3 months (T3) and 6 months (T4) after the first injection, and 2 weeks after the second injection (T2). The 201 participating HCWs were stratified according to their initial serological status. The vaccine effectiveness was also assessed through a medical questionnaire.

Results: We report here a marked and statistically significant antibody decrease (P < 0.05) between T3 and T4, especially in naïve vaccinees. The analysis of potential confounding factors or known risk factors for severe COVID-19 disease did not reveal any influence on the drop observed. Six-month after vaccination, only one, symptomatic, infection was reported in our cohort.

Conclusions: In a supply-limited environment, our results plead for reserving the 3rd dose scheme, in the upcoming months, to seronegative individuals prior to vaccination, especially when the serological status is easily accessible.

Keywords: COVID-19; Efficacy; Immunogenicity; SARS-CoV-2; mRNA-1273 vaccine.

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Conflict of interest statement

Conflicts of Competing Interest The authors have no relevant competing interest to disclose in relation to this work.

Figures

Fig 1
Fig. 1
Immunogenicity of mRNA-1273 COVID vaccine after 6 months surveillance in health care workers; a third dose is necessary It shows the titers of SARS-CoV-2 IgG antibodies directed against the subunits (S1) and (S2) of the virus spike protein before (T0), 2 weeks after the first injection (T1), 2 weeks after the second injection (T2), 3 months (T3) and 6 months (T4) after the first infection according to the participant serological status (n = 201). Data are presented with median and interquartile range. A P-value < 0.05 was considered significant.
Fig 2
Fig. 2
Odds ratio with 95% confidence interval for univariate associationwith decline in IgG between T3 and T4 in seropositive (A) and seronegative (B) HCWs.
See this image and copyright information in PMC

Comment in

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