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On GPS: What to make of Covid "Breakthrough infections"
06:26 - Source: CNN
CNN  — 

Federal health officials surprised just about everyone this week when they announced a change to guidance for fully vaccinated people, saying most should resume wearing masks inside.

The US Centers for Disease Control and Prevention also said everyone should wear masks in school – students, teachers, staff and visitors.

CDC Director Dr. Rochelle Walensky said new data had convinced her the Delta variant was “behaving uniquely.” She said the evidence indicated that fully vaccinated people who have breakthrough infections involving Delta may be as likely to transmit virus to others as unvaccinated people are.

Plus, she said, people living in areas of high or sustained transmission should start wearing masks in public again – even if they are vaccinated – because of the higher risk of becoming infected when more virus is circulating.

But she didn’t present the data, and the CDC’s website still indicates only 5,914 people have become severely ill with Covid or died despite having been vaccinated.

This as the CDC issued a health alert and held a rare briefing Tuesday to warn that the Delta variant was spreading more rapidly than previous variants, and urging people to mask back up and get vaccinated.

Had the CDC been doing more to report breakthrough infections, the change to the masking guidance might not have taken the country so much by surprise.

Instead, the seemingly sudden change in guidance looked like a flip-flop.

And it calls into question President Joe Biden’s repeated promises that his administration would not only follow the science, but would be transparent and open about it.

No vaccine is 100% effective and studies are showing that while the three authorized vaccines protect well against serious disease and illness, they are less effective in preventing any type of infection, including a mild case of Covid-19 or asymptomatic infection.

The CDC has tracked serious infections requiring hospitalization and deaths among fully vaccinated people. But it’s not publishing that data in a timely manner, and it has stopped national tracking of mild and asymptomatic infections.

That makes it hard to know if fully vaccinated people are, in fact, less likely to pass along the infection to others. It’s hard to say whether people infected with the Delta variant despite having been vaccinated are more likely to infect others.

And it’s hard to be confident that the virus is not infecting millions of fully vaccinated people and perhaps evolving in their bodies under pressure from a vaccinated immune system – a scenario that is unlikely but that could, in theory, give rise to new vaccine-impervious variants.

“I think it is important to track the symptomatic breakthrough infections. It is important to track hospitalizations and deaths – but if you don’t track all symptomatic ones, from the epidemiology point of view you don’t know the frequency and severity of those symptomatic breakthrough infections,” David Holtgrave, dean of the School of Public Health at the University at Albany, State University of New York, told CNN.

“Plus, you miss the opportunity to follow up with a sample of people with symptomatic breakthrough infections to see if they develop long haul symptoms. I don’t think we have a good handle on that. We could use better data.”

This lack of data could also have the effect of reducing vaccine confidence, Holtgrave said.

“If you want to be able to assure the nation that breakthrough infections are rare – and I believe symptomatic breakthrough infections are relatively rare even in the time of the Delta variant – you have to be able to say ‘we went out and looked very hard for those infections and we didn’t find many and when we did, they weren’t that severe,’” Holtgrave said.

“You are only as reassuring as the extent to which you went out and looked.”

The CDC did do this in looking for rare side-effects from the Covid-19 vaccines, including a rare blood clotting condition linked with the Johnson & Johnson vaccine and an unusual inflammatory response affecting the heart called myocarditis linked with the Pfizer and Moderna vaccines.

CDC promises more data

Walensky promised more data is forthcoming.

“In the coming days, you will actually see the published information on the science that motivated this change,” she told CNN’s New Day Wednesday.

She made a similar promise Tuesday.

“We are collecting passive reporting data on people who are hospitalized and who have died, but we recognize that, epidemiologically, that is not going to give us the best information with regard to rates of breakthrough infection, because passiv