Mar 29, 2021 - Health

CDC: Pfizer, Moderna vaccines are 90% effective in real-world conditions

Registered Nurse Morgan James loads a syringe with a dose of the Pfizer Covid-19 vaccine
A registered nurse loads a syringe with a dose of the Pfizer COVID-19 vaccine. Photo: Frederic Brown/AFP via Getty Images

People who are fully vaccinated with the mRNA vaccines from Pfizer or Moderna are 90% less likely to get infected with COVID-19, according to a CDC study that tested nearly 4,000 health care workers and other essential workers for the virus weekly.

Why it matters: The data show how well the vaccine performs in non-clinical trial settings. During the mRNA clinical trials for both the Pfizer and Moderna vaccines, effectiveness from full vaccination was about 95%.

By the numbers: The vaccine was 90% against infections regardless of symptom status, the report says.

  • Vaccine effectiveness of partial immunization — greater than 14 days after first dose, but before second dose — was 80%.
  • The findings provide researchers with more evidence that vaccines reduce the risk of infections, including asymptomatic ones.

What they're saying: “These findings should offer hope to the millions of Americans receiving COVID-19 vaccines each day and to those who will have the opportunity to roll up their sleeves and get vaccinated in the weeks ahead," CDC Director Rochelle Walensky, said in a statement.

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