Fourth COVID Shot Reduced the Risk of Infection by 12.9%

While the general public may feel we are post-pandemic, healthcare workers know that COVID still runs rampant worldwide, especially in hospital settings. The recent study published in JAMA Network Open looked at how a fourth COVID shot may help reduce the risk of infection for healthcare workers.

Many sources, such as Yale Medicine, refer to the BA.5 and BA.4 subvariants of the Omicron variant as the most contagious strains, accounting for more than 70% of all COVID-19 cases in the United States, with BA.5 making up over 50% of new COVID-19 cases.

This article highlights December 2021 as the beginning of the Omicron surge in Israel. Shortly after this surge, the Israeli government provided a fourth voluntary dose of the BNT162b2 vaccine (the Pfizer COVID-19 vaccine) to elderly and immunocompromised patients and healthcare workers.

The article suggests that only 19% of healthcare workers overall opted for the fourth dose due to doubts about its necessity.

“The common assumption was that the combination of reduced virulence of the Omicron variant and the protection given by the first three vaccine doses created no added value for the fourth vaccine. However, when considering vaccination of HCWs, the infection rate is equally important to complications or mortality rates because quarantine and isolation of a large number of HCWs may impair the ability of the health system to function, as observed at the beginning of the pandemic,” stated the investigators of the publication.

The study found that 25% of male healthcare workers opted for a fourth dose while only 19% of female healthcare workers did. Furthermore, the likelihood of opting for the fourth dose increased with age, with 42% of healthcare workers ages 60 and older opting for the fourth dose. Meanwhile, the percentage was 19% and 10% for the 40–59 and the under 40 age brackets, respectively.

“In this multicenter cohort study of 29,611 healthcare workers in Israel, the breakthrough infection rate among those who received four doses was 6.9% compared with 19.8% in those who received three doses,” stated the researchers in the study.

That is almost a 13% decrease in disease risk between the three- and four-dose series.

This data suggests that boosters may be considered in the event of new COVID waves. While this study has some limitations, it may be considered when making public health decisions. Additionally, as we continue to navigate new variants, those eligible for an additional booster may discuss the benefits with their healthcare provider.