COVID-19 BOOSTER VACCINE EFFECTIVENESS in PEOPLE with and WITHOUT IMMUNE DYSFUNCTION

ABSTRACT

Background: Real-world evidence on effectiveness of booster or additional doses of COVID-19 vaccine is limited. Methods: Using patient-level data from 50 sites in the U.S. National COVID Cohort Collaborative (N3C), we estimated COVID-19 booster vaccine effectiveness compared to full vaccination alone (completed 2 doses mRNA or 1 dose Janssen vaccine). At each month following full vaccination, we created comparable cohorts of patients with boosters propensity-score matched to those without boosters by age, sex, race/ethnicity, comorbidities, geographic region, prior COVID-19 infection, and calendar month of full vaccination. Booster efficacy was evaluated among patients with and without immunosuppressed/compromised conditions (ISC;HIV infection, solid organ or bone marrow transplant, autoimmune diseases, and cancer). We used Cox regression models to estimate hazards of breakthrough infection (COVID-19 diagnosis after last dose of vaccine) and logistic regression models to compare the risk of death ≤45 days after a breakthrough infection in the boosted vs. matched non-boosted groups. Results: By 11/18/2021, 656390 patients had received full vaccination, and 125409 fully vaccinated had received an additional booster (median time from last vaccine to booster dose 7.4 months, IQR6.6, 8.2). At completion of full vaccination, median age was 50 (IQR 33-64) years, 43% male, 50% white, 11% Black, 18% Latinx, 4.8% Asian American/Pacific Islander, and 20% had ISC. People receiving a booster were more likely to be older, male, white, and have ISC. Booster vaccine was significantly associated with a reduced hazard of breakthrough infection (Table). Booster efficacy ranged from 46% (booster receipt 1-4 months after full vaccination) to 83% (receipt 7 months after full vaccination) in people without ISC. Vaccine efficacy was lower, ranging from 43%-65%, in ISC patients (Table). Compared to fully vaccinated patients without booster receipt, patients with booster had an 83% (OR 0.17, 95% CI 0.11, 0.28) reduced risk of COVID-19 related death, independent of demographics, geographic region, comorbidities, ISC, prior COVID-19 infection, and time of full vaccination. Conclusion: A booster dose of COVID-19 vaccine has high effectiveness in reducing breakthrough infection risk among all fully vaccinated individuals, though only with moderate effectiveness among ISC patients. Nonetheless, booster vaccination significantly reduced risk for COVID-19 related death regardless of ISC status.