A Study on COVID-19 Vaccine Effectiveness Published

The JAMA Network Open published a study on the effectiveness of the COVID-19 vaccine. It shows the vaccine is about 55% effective in preventing COVID-19-related hospitalizations and cuts down by half the visits to emergency rooms and urgent care facilities.

While the effectiveness of COVID-19 vaccines is widely acknowledged, this study attracted significant attention because political appointees from the Trump administration halted its publication in a Centers for Disease Control and Prevention (CDC) journal. They cited the study’s design as being susceptible to errors that might lead to misleading results. However, many experts in public health believe the method is reliable and has been used for many years to assess vaccine performance.

In the accompanying commentary of the study, Natalie Dean from Emory University emphasized the importance of continuing to publish vaccine effectiveness estimates amidst changing immunity and viral evolution.

The research was initially set to appear in the CDC’s Morbidity and Mortality Weekly Report. Although it was flagged by acting CDC Director Jay Bhattacharya, who questioned its design, the authors were allowed to address the concerns or choose to publish externally, as stated by Althea Grant-Lenzy, CDC’s chief science officer.

The study used a “test-negative design” where researchers looked at patients admitted for respiratory illnesses and compared the likelihood of a positive COVID-19 test between vaccinated and unvaccinated individuals. Previously, this method has been validated with expert reviews in journals such as Pediatrics and the New England Journal of Medicine.

Bhattacharya and Martin Kulldorff criticized the design, arguing that it relies excessively on assumptions and might be swayed by factors like prior infections and different patient behaviors. Despite United States Department of Health and Human Services officials not offering a better alternative to assess real-time vaccine efficacy, this design has been defended by many as addressing differences related to care-seeking behavior.

The CDC recently convened a forum where experts deliberated the study’s methodology. Participants included Natalie Dean and others who highlighted the strengths, although Kulldorff criticized the inclusion of varying disease types in studies and questioned the absence of long-term studies during the pandemic.

According to Kulldorff, the pandemic demanded quick evaluations, a sentiment echoed by attendees.

Note: The Associated Press Health and Science Department’s content is supported by the Howard Hughes Medical Institute and the Robert Wood Johnson Foundation.