🇺🇸@COVID19Up: The CDC has stopped reporting “breakthrough cases” of COVID-19 that resulted in asymptomatic or moderate infections. Since May 14, the agency has only reported and investigated SARS-CoV-2 infections among vaccinated people that resulted in hospitalization or death. Sequencing in the U.S. has not ramped up much, either: The country is only sequencing less than 4.1% of its COVID-19 cases.
That means it’s difficult to tell exactly how much of a risk the Delta variant poses to vaccinated people. Researchers still don’t know whether Delta makes breakthrough cases more common, or what the typical symptoms of a breakthrough infection caused by Delta look like.
In a recent post for Harvard Health Publishing, Robert Shmerling, an associate professor of medicine at Harvard Medical School, called the CDC’s decision not to track all breakthrough cases “surprising” and “disappointing.”
“By tracking only cases requiring hospitalization or causing death, we may miss the chance to learn how people with ‘milder’ disease are affected by Delta or other variant infections, such as how long their symptoms last and how the infection may disrupt their lives,” Shmerling warned.
He added that the US could also miss important information about which vaccines are most effective against Delta, how long vaccine protection against the variant lasts, and whether the timing of a second vaccine dose might determine one’s likelihood of a breakthrough case.