COVID-19 vaccine effectiveness fell from 91% to 66%

Seems like the 90’s were only a few months ago.

In this case, the 90’s don’t mean the decade of the Spice Girls, frosted tips, and gigantic cells phones. It refers to the effectiveness of the Covid-19 vaccines in preventing infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A study just published in the Centers for Disease Control and Prevention (CDC) Morbidity and Mortality Weekly Report (MMWR) found Covid-19 vaccine effectiveness to be 91% from December 14, 2020, to April 10, 2021. However, in the ensuing months until August 14, 2021, this effectiveness dropped to 66%. What happened in the U.S. after mid-April? Well, one thing that happened rhymes with “felt a berry hunt.”

Yep, it’s the Delta variant. This more contagious version of the SARS-CoV-2 really started spreading throughout the U.S. in the late Spring to quickly become the predominant version of the SARS-CoV-2. After Covid-19 cases and hospitalizations had declined from the mid-Spring to June, July saw yet another surge, which has continued throughout the Summer. Amidst all this, a continuing question has been, are the available Covid-19 vaccines as effective against the Delta variant as they were against the original virus? And if not, how effective are they?

Well, this latest MMWR study sought to answer these questions. The study analyzed what happened with the HEROES-RECOVER Cohorts. These Cohorts are group of health care personnel, first responders, and other essential and frontline workers in eight different locations: Phoenix, Tucson, and other areas in Arizona; Miami, Florida; Duluth, Minnesota; Portland, Oregon; Temple, Texas; and Salt Lake City, Utah. Members of these cohorts underwent SARS-CoV-2 testing using reverse transcription–polymerase chain reaction (RT-PCR) tests every week and whenever they developed Covid-19-like symptoms. Forbes