ARI SHAPIRO, HOST:
The Centers for Disease Control and Prevention has stopped tracking every case that occurs when a COVID-19 vaccine fails to protect someone. Instead, the CDC is focusing on people who get very sick or die. It's a controversial decision. NPR health correspondent Rob Stein has the story.
ROB STEIN, BYLINE: The COVID-19 vaccines are very effective, but they're not perfect. People can still sometimes get infected. It's rare, but the CDC says more than 10,000 fully vaccinated people have still caught the virus. So the CDC has been tracking these so-called breakthrough infections to find out more about them, but the CDC recently decided to concentrate on people who are so sick they end up in the hospital or die. Here's CDC director Rochelle Walensky at a recent briefing.
(SOUNDBITE OF ARCHIVED RECORDING)
ROCHELLE WALENSKY: These vaccines were to studied to prevent severe illness, hospitalization and death. And as we look at these breakthrough infections, those are the ones we're most concerned about.
STEIN: Because in most breakthrough infections, people don't get very sick or don't even know they've been infected.
(SOUNDBITE OF ARCHIVED RECORDING)
WALENSKY: What we were starting to find is a large portion of them were fully asymptomatic. And in fact, when we went to study them and even sequence them, there was inadequate virus to even do so.
STEIN: And if scientists can't sequence genes from the virus, there's not much chance these people are contagious, and there's not much scientists can learn by studying them. But some think the CDC should be casting a much wider net.
RICK BRIGHT: Just looking at hospitalizations or cases from people who die is really keeping, I believe, blindfolds on your eyes and not fully understanding what's happening with this virus.
STEIN: Rick Bright is a former federal health official who's now with the Rockefeller Foundation.
BRIGHT: It puts us at a disadvantage of better understanding this virus and how to end the pandemic.
STEIN: Because, Bright says, investigating the full spectrum of breakthrough infections could provide crucial information about all sorts of things. Are some vaccines working better than others? Are breakthroughs happening more in some people than others? Are the variants breaking through the vaccines more than expected? Have more dangerous new mutants evolved?
BRIGHT: These variants are spreading. And if you're just looking at this small percentage, then you're really missing the big picture. You're missing the big story of where the virus is and how it's changing.
STEIN: Others agree. Saad Omer is a vaccine researcher at Yale. At the very least, Omer thinks the CDC should be randomly sequencing virus from all breakthroughs.
SAAD OMER: If there is a new variant or there is a change in frequency of a variant, you might want to find out earlier than wait for it to appear in severe and hospitalized cases. That gives you the ability to be ahead of the outbreak rather than follow it.
STEIN: Now, CDC officials say the agency isn't ignoring other breakthroughs entirely. The agency's studying how well the vaccines are working in specific groups like health care workers and at nursing homes. Dr. Marc Fischer is leading the CDC's vaccine breakthrough team.
MARC FISCHER: The CDC will continue to look at vaccine effectiveness in all populations, including people with mild infections. That's being done through special studies, vaccine effectiveness studies and other monitoring in different populations and settings.
STEIN: In addition, some individual states and independent scientists are investigating all breakthrough infections more closely. Dr. Carlos Del Rio is an infectious disease researcher at Emory University. He agrees with the CDC's approach.
CARLOS DEL RIO: I just think from a strategy and prioritizing standpoint, they're doing the right thing. They're really focusing on what matters.
STEIN: But critics still worry that the CDC's strategy could leave the country vulnerable to getting blindsided once again by whatever new threats the virus may pose. Rob Stein, NPR News.
(SOUNDBITE OF CITY OF THE SUN'S "VENTURA") Transcript provided by NPR, Copyright NPR.
