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Tai CG, Maragakis LL, Connolly S, et al. Association Between COVID-19 Booster Vaccination and Omicron Infection in a Highly Vaccinated Cohort of Players and Staff in the National Basketball Association. JAMA. Published online June 02, 2022. doi:10.1001/jama.2022.9479
Evaluation of COVID-19 vaccine booster effectiveness is essential as new variants of SARS-CoV-2 emerge. Data support the effectiveness of booster doses in preventing severe disease and hospitalization; however, the association with reducing incident SARS-CoV-2 infections is not clear.1-3 We compared the incidence of SARS-CoV-2 infection in players and staff of the National Basketball Association (NBA) who did vs those who did not receive a booster dose.
Players and staff who were tested more than once between December 1, 2021, and January 15, 2022, were included. Individuals were tested via the nucleic acid amplification test when symptomatic, after a known exposure, or during daily enhanced surveillance testing triggered by multiple cases on 1 team. Player vaccinations were not mandated. Staff were required to be fully vaccinated by October 1, 2021, and to have received a booster dose by January 5, 2022, if eligible. Masking requirements were similar between players and staff, with the exceptions of players unmasking on court and head coaches unmasking during games.
Genome sequencing was performed for all infections to determine the SARS-CoV-2 variant, but some sequencing failed due to inadequate sample volume, viral load, or genome coverage. Vaccination status was considered as a time-varying exposure; individuals could dynamically move through multiple categories during the study and contribute person-days accordingly. Fully vaccinated was defined as 2 doses of a 2-dose vaccination course (Pfizer-BioNTech BNT162b2 or Moderna mRNA-1273) or 1 dose of the 1-dose vaccination course (Johnson & Johnson JNJ-78436735)4 and fully boosted was defined as 14 days after receiving any booster dose.
Hazard ratios (HRs) from an Andersen-Gill Cox proportional hazards model5 compared time to infection for individuals who were fully vaccinated vs those who were fully boosted. Infections occurring after vaccination but prior to 14 days after vaccination were censored. The outcomes included confirmed SARS-CoV-2 infections, symptomatic infections, COVID-19 hospitalizations, and COVID-19 deaths.
The models were adjusted for age and prior SARS-CoV-2 infection and the analyses were performed using SAS version 8.2 (SAS Institute Inc) and R version 4.1.1 (R Foundation for Statistical Computing). Statistical significance was defined as a 2-sided P < .05. The Advarra institutional review board determined the study met criteria for exemption status. Individuals signed health information authorizations allowing collection, storage, and use of health information by the NBA for monitoring purposes, including disclosure to medical experts.
Of 2613 players and staff, 67% were followed up the entire 45-day study period, with 74 165 person-days contributed by fully boosted individuals and 10 890 person-days by those who were fully vaccinated but not boosted though eligible to receive a booster dose. From the start to the end of the study period, the percentage of individuals who were fully vaccinated and eligible for a booster dose decreased from 26% (n = 682) to 8% (n = 205) and the percentage of individuals who were fully boosted increased from 49% (n = 1282) to 85% (n = 2215); the remainder were in other categories, such as fully vaccinated but not yet eligible for a booster or within 14 days of their booster dose. In the overall cohort, 88% were male with a median age of 33.7 years (IQR, 27.3-45.2 years; Table 1).
Individuals who were fully boosted experienced 608 confirmed SARS-CoV-2 infections and were significantly less likely to be infected than fully vaccinated individuals who were booster eligible and had not received a booster, who had experienced 127 confirmed infections (adjusted HR, 0.43 [95% CI, 0.35-0.53], P < .001; Table 2). The secondary analyses evaluating symptomatic infection showed a similar association (adjusted HR, 0.39 [95% CI, 0.30-0.50]; P < .001). No hospitalizations or deaths occurred. Omicron was the dominant variant, representing 93% of 339 sequenced cases.
This study found that in a young, healthy, highly vaccinated cohort frequently monitored for SARS-CoV-2, booster vaccination was associated with a significant reduction in incident infections during the Omicron wave. Study limitations include generalizability to older populations and the possibility that some infections may have been undetected in the absence of daily surveillance testing. This is a population that was recently boosted (median of 20 days as of December 1, 2021) and may not reflect waning efficacy over time. Surveillance testing in this population captured both symptomatic and asymptomatic infections, which differs from studies of the effectiveness of boosters that did not assess risk of asymptomatic infections.2,3 Continued research is required to assess the need for additional booster doses beyond a single booster dose.
Accepted for Publication: May 20, 2022.
Published Online: June 2, 2022. doi:10.1001/jama.2022.9479
Corresponding Author: Christina DeFilippo Mack, PhD, MSPH, IQVIA, 4820 Emperor Blvd, Durham, NC 27703 (firstname.lastname@example.org).
Author Contributions: Drs Tai and Mack had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Drs Grad and Mack are joint senior authors on this work.
Concept and design: All authors.
Acquisition, analysis, or interpretation of data: Tai, Maragakis, Connolly, Grad, Mack.
Drafting of the manuscript: All authors.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Tai, Connolly.
Administrative, technical, or material support: Tai, Connolly, Mack.
Supervision: Tai, Maragakis, DiFiori, Grad, Mack.
Conflict of Interest Disclosures: Drs Tai, Connolly, and Mack are employees of IQVIA, which is in a paid consultancy with the National Basketball Association (NBA). Dr Maragakis reported receiving support from the US Centers for Disease Control and Prevention (CDC) and the Agency for Healthcare Research and Quality; receiving personal fees while serving as a paid consultant to the NBA; and serving as a co-chair of the Healthcare Infection Control Practices Advisory Committee of the CDC. Dr DiFiori reported receiving consulting fees from the NBA. Dr Anderson reported receiving institutional support from the CDC, the Agency for Healthcare Research and Quality, and the National Institute of Allergy and Infectious Diseases; receiving royalties from Up To Date; and ownership of Infection Control Education for Major Sports. Dr Grad reported receiving support from the National Institutes of Health, the Smith Family Foundation, Welcome Trust, Pfizer, and Merck; receiving consulting fees from GlaxoSmithKline, Quidel, and the NBA; receiving payment for expert testimony from Merck; having a provisional patent application for Neisseria gonorrhoeae therapies; and serving on the scientific advisory board for Day Zero Diagnostics. No other disclosures were reported.
Funding/Support: This work was funded by the NBA in the interest of player, staff, and community health.
Role of the Funder/Sponsor: NBA employees had a role in the design and conduct of the study; collection, management, and interpretation of the data; preparation, review, and approval of the manuscript; and decision to submit the manuscript for publication.
Additional Contributions: We thank David D. Ho, MD (Aaron Diamond AIDS Research Center, Columbia University Vagelos College of Physicians and Surgeons); Michael H. Merson, MD (Duke Global Health Institute); Leroy Sims, MD (NBA); and Eleanor Adams, MD, MPH (NBA) for their advisory on the interpretation of these results and critical review of the manuscript. Drs Ho and Merson did not receive compensation specifically for this study. Drs Sims and Adams are paid employees of the NBA. We also thank the NBA Players Association, the NBA Team Physicians Association, and the athletic training staff and compliance officers for the collection of these data. We thank the analytic and operational teams at the NBA and IQVIA for their tireless work on the NBA COVID-19 monitoring program operations as well as protocol implementation and evolution by the following individuals: David Weiss, JD, Miheer Mhatre, JD, Taylor Walden, MS, Peter Meisel, MSPH, Rachel Davis, MPH, Kelly Hogan, and Wes Harris, MS (paid employees of the NBA); and Miriam Haviland, PhD, Kendall Knuth, MPH, Radhika M. Samant, MPH, Kristina Zeidler, MPH, Gabriel Farkas, MA, Riju Shrestha, MPH, Saamir Pasha, MPH, Rahul Gondalia, PhD, Tiffany Koch, Michael Booth, MBA, Tiffany Siber-Wolff, MBA, and Alexis Blum (employees of IQVIA, which has a paid consultancy with the NBA).