Reference:
Israel, A., Shenhar, Y., Green, I., Merzon, E., Golan-Cohen, A., Schäffer, A. A., Ruppin, E., Magen, E., & Vinker, S. (2021). Elapsed time since BNT162b2 vaccine and risk of SARS-CoV-2 infection in a large cohort. medRxiv. https://doi.org/10.1101/2021.08.03.21261496
Summary:
This study investigates the decay of SARS-CoV-2 IgG antibodies in individuals vaccinated with two doses of BNT162b2 mRNA vaccine compared to those who recovered from COVID-19. The research included 2,653 vaccinated individuals and 4,361 convalescent patients. Results showed that vaccinated individuals had significantly higher initial antibody levels (median 1581 AU/mL) than convalescents (median 355.3 AU/mL). However, antibody levels in vaccinated individuals decreased by approximately 40% each month, while convalescents experienced a decline of less than 5% monthly. Six months post-vaccination, 16.1% of vaccinated individuals had antibody levels below the protective threshold, compared to 10.8% of convalescents after nine months. The findings highlight the differing kinetics of antibody responses between vaccinated and convalescent individuals, suggesting a need for ongoing monitoring and potential booster vaccinations for vaccinated populations.