Pfizer-BioNTech (BNT162b2) Vaccine Effectiveness against Symptomatic Laboratory-Confirmed COVID-19 Infection among Outpatients in Sentinel Sites, Lebanon, July–December 2021

Abstract

On 14 February 2021, Lebanon implemented nationwide vaccination, offering the Pfizer-BioNTech (BNT162b2) vaccine to adults over 50 years of age. We estimated the effectiveness of the Pfizer-BioNTech vaccine in preventing symptomatic laboratory-confirmed COVID-19. We conducted a test-negative case–control (TND) study among symptomatic adults aged 50 years and older who presented with influenza-like illness (ILI) or COVID-19-like illness (CLI) in surveillance sentinel sites between 1 July and 31 December 2021. Unvaccinated participants did not receive any vaccine dose before symptom onset. Vaccinated participants received at least one dose within 14 days before onset of symptoms. We estimated vaccine effectiveness against symptomatic laboratory-confirmed COVID-19, adjusted for demographic and behavioral factors, using multivariable logistic regression. Out of 457 participants with symptoms, 150 (33%) were positive and 307 (67%) were negative for SARS-CoV-2. Adjusted vaccine effectiveness was 22% (95% CI: −70–65%) for those partially vaccinated and 44% (95% CI: 6–67%) for those fully vaccinated. Vaccination with two doses of the Pfizer-BioNTech vaccine was effective in preventing COVID-19 symptomatic illness in the older population. Vaccine effectiveness was lower for those partially vaccinated. We recommend enhancing vaccine uptake with at least one dose among risk groups for COVID-19 and keeping general recommendations on contact and droplet precautions in the general population.

Keywords

• COVID-19
• vaccine
• effectiveness
• symptomatic outcome