Delta Variant Diminished COVID-19 Vaccine Effectiveness

During the U.S. FDA's Vaccines and Related Biological Products advisory meeting held on September 17, 2021, Sara Oliver M.D., MSPH, presented updates to COVID-19 Epidemiology and COVID-19 Vaccine Effectiveness.

Dr. Oliver's presentation indicates the Delta coronavirus variant has significantly reduced protection against infection (including asymptomatic or mild infections) from the 380 million COVID-19 vaccines administered in the USA during the June-July timeframe.

The U.S. CDC reported data on September 16, 2021, representing about 54.2% of the US population had been fully vaccinated with a COVID-19 vaccine.

The vast majority of COVID-19 vaccines administered in 2021 are the Comirnaty and SpikeVax vaccines.

COVID-19 vaccines effectively prevent mild symptoms, severe disease, and hospitalizations due to COVID-19 disease. But it is still possible for a fully vaccinated person to become infected if exposed to the SARS-CoV-2 betacoronavirus.

The CDC reported fatal Breakthrough Cases reached 2,675 as of September 7, 2021.

Note: Dr. Oliver confirmed that the CDC's COVID-19 vaccine effectiveness calculations had not included the impact of natural immunity generated from a previous SARS-CoV-2 infection.