Severe outcomes rare after two COVID vaccine doses


Two COVID-19 vaccine studies published today respectively identify risk factors for severe outcomes among adults given two doses and describe cancer patients’ antibody response to two or three doses.

Adverse outcomes exceedingly rare

A Morbidity and Mortality Weekly Report (MMWR) study by National Institutes of Health (NIH) and Centers for Disease Control and Prevention (CDC) researchers involved 1,228,644 American adults who completed their primary COVID-19 vaccination regimen from December 2020 to October 2021. The period was marked by the emergence of the more transmissible Delta (B1617.2) variant.

The researchers used data from 465 healthcare facilities in the Premier Healthcare Database Special COVID-19 Release to evaluate the frequency of and risk factors for severe COVID-19 after two doses of the mRNA COVID-19 vaccines from Pfizer/BioNTech or Moderna or one dose of the Johnson & Johnson (J&J) vaccine 14 or more days before illness onset. Of all vaccinees, 72.8% received Pfizer, 20% were given Moderna, 6.5% received J&J, and 0.8% received an unspecified vaccine.



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