Real-world data reveal that the Pfizer-BioNTech and Moderna COVID-19 vaccines are effective in preventing asymptomatic and symptomatic SARS-CoV-2 infection and are recommended for all patients who are eligible, according to Morbidity and Mortality Weekly Report (MMWR) put forth by the Centers for Disease Control and Prevention earlier this week.

While the efficacy of both vaccines has been demonstrated in randomized, placebo-controlled phase 3 studies, little data on their effectiveness in real-world conditions has been reported. In this MMWR, interim estimates of the effectiveness of these vaccines in the prevention of symptomatic and asymptomatic SARS-CoV-2 infection in a real-world setting were discussed.

“Using prospective cohorts of health care personnel, first responders, and other essential and frontline workers in 8 US locations during December 14, 2020–March 13, 2021, CDC routinely tested for SARS-CoV-2 infections every week regardless of symptom status and at the onset of symptoms consistent with COVID-19–associated illness,” the study authors reported. The analysis included a total of 3950 participants; 62.8% (n=2479) received the recommended 2 doses of the vaccine and 12.1% (n=477) received only 1 dose.

Findings of the analysis revealed that the effectiveness of vaccination against SARS-CoV-2 infection in participants who had been fully immunized (at least 14 days after second dose) was 90% regardless of symptom status. Data analysis also showed that vaccine effectiveness in participants who had been partially immunized (at least 14 days after first dose but prior to second dose) was 80%.

“These interim vaccine effectiveness findings for both Pfizer- BioNTech’s and Moderna’s mRNA vaccines in real-world conditions complement and expand upon the vaccine effectiveness estimates from other recent studies and demonstrate that current vaccination efforts are resulting in substantial preventive benefits among working-age adults,” the report concluded.


Thompson MG, Burgess JL, Naleway AL, et al. Interim estimates of vaccine effectiveness of BNT162b2 and mRNA-1273 COVID-19 vaccines in preventing SARS-CoV-2 infection among health care personnel, first responders, and other essential and frontline workers — Eight U.S. Locations, December 2020–March 2021. MMWR Morb Mortal Wkly Rep 2021;70:495–500.