COVID-19 in the NBA: Omicron Infection by Booster Vaccination Status

Recently, debates surrounding COVID-19 vaccine boosters have been heating up. As the Omicron variant continues to dominate and mutate, the Food and Drug Administration’s (FDA’s) Vaccine and Related Biological Products Advisory Committee (VRBPAC) voted to recommend including an Omicron component in upcoming COVID-19 booster vaccines.

However, some experts, including the 2 of 21 VRBPAC members who voted against the recommendation, worry this sends a message that current COVID-19 boosters offer insufficient protection. A recent study, published in JAMA, examined the efficacy of current COVID-19 vaccine boosters against Omicron in a high-profile, highly vaccinated cohort: the National Basketball Association (NBA).

The investigators compared the incidence of COVID-19 infections in NBA players and staff who did receive a booster shot versus those who did not. Players and staff were included if they were tested for COVID-19 more than once from December 1, 2021-January 15, 2022. They were tested with a nucleic acid amplification test when symptomatic, after known exposure, or during daily enhanced surveillance testing implemented after multiple players on a team tested positive.

The NBA mandated COVID-19 vaccination for staff, but not for players. Staffers had to be fully vaccinated by October 1, 2021, and if eligible, had to receive a booster dose by January 5, 2022. Overall, NBA players and staff had similar masking recommendations, though players could unmask while on the court and head coaches could unmask during games.

The investigators performed genome sequencing for all confirmed infections to determine the COVID-19 variant, though some failed due to inadequate sample volume, viral load, or genome coverage. Full vaccination was defined as 2 doses of an approved 2-dse vaccination course (Pfizer-BioNTech or Moderna) or 1 dose of the 1-dose approved Johnson & Johnson vaccine. Vaccination status was considered as a time-varying exposure.

Using hazard ratios from an Andersen-Gill Cox proportional hazards model, the investigators compared time to infection between individuals who were fully vaccinated and those who were full vaccinated and boosted. Study outcomes included confirmed COVID-19 infections, symptomatic infections, hospitalizations, and deaths. COVID-19 infections were not included if they occurred after vaccination but before 14 days had elapsed. The models were adjusted for age and prior COVID-19 infection.

Of 2613 NBA players and staffers, 67% were followed through the entire 45-day study period, for a total of 10890 person-days contributed by fully vaccinated individuals and 74165 person-days from fully vaccinated and boosted individuals. The NBA cohort was 88% male and averaged 33.7 years of age.

Through the course of the study, the proportion of study participants fully vaccinated and eligible for a booster decreased from 26% (n= 682) to 8% (n = 205). The proportion of those fully boosted increased from 49% (n = 1282) to 85% (n = 2215). The rest of the NBA cohort were in other categories, such as vaccinated but not yet eligible for a booster, or within 14 days of their booster.

The fully vaccinated and boosted NBA players and staffers experienced 608 confirmed infections. They were overall significantly less likely to contract COVID-19 than the fully vaccinated individuals who had not been boosted despite eligibility, for a hazard ratio of 0.43. No hospitalizations nor deaths occurred in the NBA cohort. Notably, Omicron was the dominant variant during the study period, accounting for 93% of 339 sequenced COVID-19 infections.

This young, healthy, highly vaccinated NBA cohort was frequently monitored for COVID-19. The study showed that booster vaccinations significantly reduced COVID-19 infections during the Omicron wave. As this population was recently boosted, it may not adequately reflect waning vaccine efficacy over time. The investigators recommended further research to assess the need for additional COVID-19 booster doses.