Waning of BNT162b2 Vaccine Protection against SARS-CoV-2 Infection in Qatar

Abstract

Background Waning 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. Methods We 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. Results Estimated 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. Conclusions BNT162b2-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.)

COVID-19 breakthrough infections and pre-infection neutralizing antibody

“…15 The vaccine effectiveness against the Delta variant infection after 4 months was 53% in the U.S. 4 and 35.1% in Qatar. 5 It is clear that a hospital-wide vaccination program alone cannot eliminate the risk of the infection by the Delta variant.…”

“…1,2 In countries with high coverage of vaccination programs, however, the number of COVID-19 patients has started growing, which has been attributed to the emergence of Variants of Concern, especially the Delta (B.1.617.2) variant, 3,4 and the waning of vaccine efficacy over time. 5,6 Epidemiological evidence is scarce regarding the role of vaccine-induced immunogenicity against Variants of Concern. In a case-control study among vaccinated healthcare workers, patients with breakthrough infection during the epidemic of the Alpha (B.1.1.7) variant had significantly lower peri-infection neutralizing antibody titers than controls.…”

Covid-19: Antibody levels fall after second Pfizer dose, but protection against severe disease remains, studies indicate

“…A second study, also published in New England Journal of Medicine , looked at the effectiveness of the Pfizer vaccine against SARS-CoV-2 infection and disease in Qatar 2…”

Boosters appear effective, but are they always needed?

“… 8 Other reports from Israel and Qatar indicate speedily declining protection. 2 , 3 Although these reports strengthen the case for a booster dose of BNT162b2, there is no evidence yet to suggest that global policies related to other vaccines should be influenced by this experience.…”

“…Currently approved vaccines provide high levels of protection against serious illness, but do not confer mucosal immunity to resist entry of the virus into the respiratory tract. When mostly mild breakthrough infections were reported from different countries, 1 , 2 , 3 concern arose that individuals with a fast fading immune response to the standard vaccination schedule might experience serious illness if infected. 1…”