U.S. CDC Finds mRNA COVID-19 Vaccines Very Effective
The U.S. CDC Morbidity and Mortality Weekly Report published on April 28, 2021, reported experimental mRNA COVID-19 vaccines are very effective.
The CDC confirmed 'a multistate network of U.S. hospitals during January–March 2021, receipt of Pfizer-BioNTech or Moderna COVID-19 vaccines was 94% effective against COVID-19 hospitalization among fully vaccinated adults and 64% effective among partially vaccinated adults aged ≥65 years.'
In this new CDC report, Pfizer-BioNTech and Moderna vaccine products were equally represented. Approximately one-half of the patients were aged ≥75 years, providing evidence of the real-world effectiveness of both vaccines against an important measure of severe COVID-19 in older adults.
Moreover, in assessing the impact of receiving only a single dose, no significant vaccine effectiveness <14 days after the first dose of a SARS-CoV-2 vaccine was detected.
This suggests that bias is unlikely in the primary estimates of vaccine effectiveness from partial and full vaccination.
This also highlights the continued risk for severe illness shortly after vaccination, before a protective immune response has been achieved from the second dose of a 2-dose mRNA vaccine.