• Hiam Chemaitelly, Patrick Tang, Mohammad R Hasan, Sawsan AlMukdad, Hadi M Yassine, Fatiha M Benslimane, Hebah A Al Khatib, Peter Coyle, Houssein H Ayoub, Zaina Al Kanaani, Einas Al Kuwari, Andrew Jeremijenko, Anvar H Kaleeckal, Ali N Latif, Riyazuddin M Shaik, Abdul RahimHanan FHFFrom the Infectious Disease Epidemiology Group (H.C., S.A., L.J.A.-R.) and the World Health Organization Collaborating Center for Disease Epidemiology Analytics on HIV/AIDS, Sexually Transmitted Infections, and Viral Hepatitis (H.C., S, Gheyath K Nasrallah, Mohamed G Al Kuwari, Hamad E Al Romaihi, Adeel A Butt, Mohamed H Al-Thani, Abdullatif Al Khal, Roberto Bertollini, and Laith J Abu-Raddad.
• From the Infectious Disease Epidemiology Group (H.C., S.A., L.J.A.-R.) and the World Health Organization Collaborating Center for Disease Epidemiology Analytics on HIV/AIDS, Sexually Transmitted Infections, and Viral Hepatitis (H.C., S.A., L.J.A.-R.), Weill Cornell Medicine-Qatar, Cornell University, Qatar Foundation-Education City, the Department of Pathology, Sidra Medicine (P.T., M.R.H.), the Biomedical Research Center, Member of QU Health (H.M.Y., F.M.B., H.A.A.K., P.C., G.K.N.), the Departments of Biomedical Science (H.M.Y., F.M.B., H.A.A.K., G.K.N.) and Public Health (H.F.A.R., L.J.A.-R.), College of Health Sciences, and the Mathematics Program, Department of Mathematics, Statistics, and Physics, College of Arts and Sciences (H.H.A.), Qatar University, Hamad Medical Corporation (P.C., Z.A.K., E.A.K., A.J., A.H.K., A.N.L., R.M.S., A.A.B., A.A.K.), Primary Health Care Corporation (M.G.A.K.), and the Ministry of Public Health (H.E.A.R., M.H.A.-T., R.B.) - all in Doha, Qatar; Wellcome-Wolfson Institute for Experimental Medicine, Queens University, Belfast, United Kingdom (P.C.); and the Department of Population Health Sciences, Weill Cornell Medicine, Cornell University, New York (A.A.B., L.J.A.-R.).
• N. Engl. J. Med. 2021 Dec 9; 385 (24): e83e83.

BackgroundWaning of vaccine protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or coronavirus disease 2019 (Covid-19) is a concern. The persistence of BNT162b2 (Pfizer-BioNTech) vaccine effectiveness against infection and disease in Qatar, where the B.1.351 (or beta) and B.1.617.2 (or delta) variants have dominated incidence and polymerase-chain-reaction testing is done on a mass scale, is unclear.MethodsWe used a matched test-negative, case-control study design to estimate vaccine effectiveness against any SARS-CoV-2 infection and against any severe, critical, or fatal case of Covid-19, from January 1 to September 5, 2021.ResultsEstimated BNT162b2 effectiveness against any SARS-CoV-2 infection was negligible in the first 2 weeks after the first dose. It increased to 36.8% (95% confidence interval [CI], 33.2 to 40.2) in the third week after the first dose and reached its peak at 77.5% (95% CI, 76.4 to 78.6) in the first month after the second dose. Effectiveness declined gradually thereafter, with the decline accelerating after the fourth month to reach approximately 20% in months 5 through 7 after the second dose. Effectiveness against symptomatic infection was higher than effectiveness against asymptomatic infection but waned similarly. Variant-specific effectiveness waned in the same pattern. Effectiveness against any severe, critical, or fatal case of Covid-19 increased rapidly to 66.1% (95% CI, 56.8 to 73.5) by the third week after the first dose and reached 96% or higher in the first 2 months after the second dose; effectiveness persisted at approximately this level for 6 months.ConclusionsBNT162b2-induced protection against SARS-CoV-2 infection appeared to wane rapidly following its peak after the second dose, but protection against hospitalization and death persisted at a robust level for 6 months after the second dose. (Funded by Weill Cornell Medicine-Qatar and others.).Copyright © 2021 Massachusetts Medical Society.

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