Elapsed time since BNT162b2 vaccine and risk of SARS-CoV-2 infection: test negative design study

Abstract

Objectives To determine whether time elapsed since the second injection of the Pfizer-BioNTech BNT162b2 mRNA vaccine was significantly associated with the risk of covid-19 infection after vaccination in people who received two vaccine injections. Design Test negative design study. Setting Electronic health records of a large state mandated healthcare organisation, Israel. Participants Adults aged ≥18 years who had received a reverse transcription polymerase chain reaction (RT-PCR) test between 15 May 2021 and 17 September 2021, at least three weeks after their second vaccine injection, had not received a third vaccine injection, and had no history of covid-19 infection. Main outcome measures Positive result for the RT-PCR test. Individuals who tested positive for SARS-CoV-2 and controls were matched for week of testing, age category, and demographic group (ultra-orthodox Jews, individuals of Arab ancestry, and the general population). Conditional logistic regression was adjusted for age, sex, socioeconomic status, and comorbid conditions. Results 83 057 adults received an RT-PCR test for SARS-CoV-2 during the study period and 9.6% had a positive result. Time elapsed since the vaccine injection was significantly longer in individuals who tested positive (P<0.001). Adjusted odds ratio for infection at time intervals >90 days since vaccination were significantly increased compared with the reference of <90 days: 2.37 (95% confidence interval 1.67 to 3.36) for 90-119 days, 2.66 (1.94 to 3.66) for 120-149 days, 2.82 (2.07 to 3.84) for 150-179 days, and 2.82 (2.07 to 3.85) for ≥180 days (P<0.001 for each 30 day interval). Conclusions In this large population of adults tested for SARS-CoV-2 by RT-PCR after two doses of mRNA BNT162b2 vaccine, a gradual increase in the risk of infection was seen for individuals who received their second vaccine dose after at least 90 days.

Vaccine effectiveness against severe acute respiratory infections (SARI) COVID-19 hospitalisations estimated from real-world surveillance data, Slovenia, October 2021

“…This finding suggested that more than half of the elderly people fully vaccinated 6 months or more ago were no longer sufficiently protected against hospitalisation due to severe COVID-19. Waning immunity has also been reported by others [11][12][13]. Thus, our results provide additional evidence of substantially declining protection with time since vaccination against hospitalisation due to severe COVID-19 in elderly people and the need for a timely booster dose, especially in this age group.…”

Mucosal immune response in BNT162b2 COVID-19 vaccine recipients

“…22,23 Indeed, cases of vaccinated subjects who become infected are commonly observed, especially several months after the injection. 24 This is due to the fact that these vaccines induce a specific and potent systemic immunity against the virus but are not very efficient in promoting a specific immunity at the level of the mucosae which represent the virus route of entry. 25,26 In order to better investigate this aspect, we undertook a comparative analysis of serum and mucosal anti-SARS-CoV-2 antibodies by focusing also on the more prevalent antibody class present in the mucosa, the IgA antibody isotype.…”

Large-Scale Study of Antibody Titer Decay following BNT162b2 mRNA Vaccine or SARS-CoV-2 Infection

“…More than five million Israelis (out of 9.3 million) were fully vaccinated with two doses of the Pfizer-BioNTech vaccine as of 26 May 2021 [8]. However, in summer 2021, there was a resurgence of SARS-CoV-2 cases in Israel. It is important to understand to what extent this resurgence is due to the high infectiousness of the delta variant [9], lower protection of the vaccine against the delta or other variants as compared to the original strain [10,11], or decreasing levels of anti-SARS-CoV-2 antibodies against all strains in vaccinated individuals [12].…”