Protection of mRNA vaccines against hospitalized COVID-19 in adults over the first year following authorization in the United States
Pulmonary/Critical Care Medicine
Background: COVID-19 mRNA vaccines were authorized in the United States in December 2020. Although vaccine effectiveness (VE) against mild infection declines markedly after several months, limited understanding exists on the long-term durability of protection against COVID-19-associated hospitalization.
Methods: Case control analysis of adults (≥18 years) hospitalized at 21 hospitals in 18 states March 11 - December 15, 2021, including COVID-19 case patients and RT-PCR-negative controls. We included adults who were unvaccinated or vaccinated with two doses of a mRNA vaccine before the date of illness onset. VE over time was assessed using logistic regression comparing odds of vaccination in cases versus controls, adjusting for confounders. Models included dichotomous time (<180 vs ≥180 days since dose two) and continuous time modeled using restricted cubic splines.
Results: 10,078 patients were included, 4906 cases (23% vaccinated) and 5172 controls (62% vaccinated). Median age was 60 years (IQR 46-70), 56% were non-Hispanic White, and 81% had ≥1 medical condition. Among immunocompetent adults, VE <180 days was 90% (95%CI: 88-91) vs 82% (95%CI: 79-85) at ≥180 days (p < 0.001). VE declined for Pfizer-BioNTech (88% to 79%, p < 0.001) and Moderna (93% to 87%, p < 0.001) products, for younger adults (18-64 years) [91% to 87%, p = 0.005], and for adults ≥65 years of age (87% to 78%, p < 0.001). In models using restricted cubic splines, similar changes were observed.
Conclusion: In a period largely pre-dating Omicron variant circulation, effectiveness of two mRNA doses against COVID-19-associated hospitalization was largely sustained through 9 months.
Keywords: COVID-19; duration of protection; mRNA; vaccine effectiveness; waning.
Tenforde MW, Self WH, Zhu Y, Naioti EA, Gaglani M, Ginde AA, Jensen K, Talbot HK, Casey JD, Mohr NM, Zepeski A, McNeal T, Ghamande S, Gibbs KW, Files DC, Hager DN, Shehu A, Prekker ME, Erickson HL, Gong MN, Mohamed A, Johnson NJ, Srinivasan V, Steingrub JS, Peltan ID, Brown SM, Martin ET, Monto AS, Khan A, Hough CL, Busse LW, Ten Lohuis C, Duggal A, Wilson JG, Qadir N, Chang SY, Mallow C, Rivas C, Babcock HM, Kwon JH, Exline MC, Botros MM, Lauring AS, Shapiro NI, Halasa N, Chappell JD, Grijalva CG, Rice TW, Jones ID, Stubblefield WB, Baughman A, Womack KN, Rhoads JP, Lindsell CJ, Hart KW, Turbyfill C, Olson S, Murray N, Adams K, Patel MM; Influenza and Other Viruses in the Acutely Ill (IVY) Network. Protection of mRNA vaccines against hospitalized COVID-19 in adults over the first year following authorization in the United States. Clin Infect Dis. 2022 May 17:ciac381. doi: 10.1093/cid/ciac381. Epub ahead of print.