Sumary of Covid US: Vaccine effectiveness against infection fell from 91% to 78% after Delta became dominant:
- COVID-19 vaccine effectiveness fell against infection after the Delta variant became dominant in the U.S., but remained high against hospitalization and death.
- This means that, according to the CDC, fully vaccinated Americans are five times less likely to contract Covid, 10 times less likely to be hospitalized and 11 times more likely to die.
- The report is part of a growing body of evidence that the vaccines became less effective after the highly transmissible Delta variant started circulating, but that they still protect recipients against the most severe outcomes linked to the virus.
- Pictured: Number of cases per 100,000 among unvaccinated people (black line) versus vaccinated people (blue line) from April to July The effectiveness against hospitalizations barely fell from 92% to 90% effective and barely fell against from 94% to 91%.
- Pictured: Number of hospitalizations per 100,000 among unvaccinated people (black line) versus vaccinated people (blue line) on left;
- deaths per 100,000 among unvaccinated versus vaccinated on rightFor the report, the team looked at COVID-19 cases, hospitalizations and deaths in 13 U.S. jurisdictions between April 4 and July 17.The study period was split in two: from April 4 to June 19, before the Delta variant was dominant;
- and June 19 to July 17, after the Delta variant made up more than 50 percent of all cases.
- During the pre-Delta dominance period, fully vaccinated Americans made up five percent of Covid cases, seven percent of hospitalizations and eight percent of deaths.