As the Delta variant swept through the US, vaccine effectiveness at preventing infection fell from about 90% to 66%, according to an updated CDC study of more than 4,000 frontline health workers.
Most of the workers in 6 states had been vaccinated with either Pfizer or Moderna jabs and had 91% protection against symptomatic and asymptomatic infection between December and April, STAT reports. However, data through August 14 revealed the sharp reduction in vaccine effectiveness.
Experts warned against reading too much into a single real-world study, though other studies have also revealed declines in vaccine effectiveness.
But: Another CDC report, this one based on data from Los Angeles County from May to July, buoys confidence in vaccines, CIDRAP reports.
- Unvaccinated people were 5X as likely to get COVID-19 than vaccinated peers.
- They were 29X more likely to be hospitalized than those vaccinated.
The Quote: “The data reminds us that if you are not vaccinated you are the highest at risk,” CDC Director Rochelle Walensky said yesterday.