Postexposure-vaccine-prophylaxis against COVID-19

Area of Science:

• Immunology
• Public Health
• Epidemiology

Background:

• Current COVID-19 protocols primarily involve patient isolation post-exposure, with no established therapeutic prevention.
• The effectiveness of administering vaccines shortly after potential SARS-CoV-2 exposure (postexposure vaccine prophylaxis) has not been widely studied.

Purpose of the Study:

• To investigate the potential mortality reduction associated with postexposure vaccine prophylaxis for COVID-19.
• To evaluate the effectiveness of receiving the first dose of the BNT162b2 vaccine on the day of or within five days of SARS-CoV-2 infection.

Main Methods:

• Utilized data from the Israeli Ministry of Health registry for PCR-positive SARS-CoV-2 cases aged 12 and older between December 20, 2020, and October 7, 2021.
• Compared mortality rates between individuals who received their first BNT162b2 vaccine dose on the day of or within five days of a positive PCR test and an unvaccinated control group.

Main Results:

• In individuals over 65, postexposure vaccine prophylaxis was associated with a significant reduction in mortality (10.13% vs. 18.06%, OR 0.51, p < 0.001).
• A significant reduction in deaths was also observed in the 55-64 age group (0.61% vs. 1.82%, OR 0.33, p = 0.007).

Conclusions:

• Postexposure vaccine prophylaxis demonstrates effectiveness in reducing mortality following COVID-19 infection.
• These findings suggest a potential benefit of early vaccination, even shortly after exposure, in mitigating severe outcomes of SARS-CoV-2 infection.