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Delta variant: Unvaccinated and vaccinated people 'are not in the same ballpark' of risk, doctor explains

Amid fears of new variants emerging and evading COVID-19 vaccines, health experts are repeatedly pointing out that being fully vaccinated is very different from being unvaccinated.

“We have to be very clear about who we’re talking about,” Dr. Jeremy Faust, an emergency physician at Brigham and Women's Hospital and an instructor at Harvard Medical School, said on Yahoo Finance Live (video above). “The Delta variant is extraordinarily dangerous for the unvaccinated, and it presents a problem for the vaccinated that the previous variant did not, but they’re not in the same ballpark. When we see the implications of most breakthrough infections, it is a small fraction of the problem that we saw without vaccination.”

According to an analysis of 38 states and D.C. by the New York Times, unvaccinated Americans in those states were five times more likely than vaccinated Americans to be hospitalized with COVID-19 and eight times more likely to die. A CDC study found that between May 1 and July 25, 2021, unvaccinated residents of Los Angeles County, California, were 29 times more likely to be hospitalized by COVID-19 than their fully vaccinated counterparts.

'Not convinced that boosting everybody is actually what’s necessary'

The CDC recently announced that booster shots are now available for immunocompromised Americans, which includes those with certain underlying conditions or taking specific immunosuppressants.

The Department of Health and Human Services (HHS) stated that boosters would become available for all Americans eight months after their second dose of the COVID-19 vaccine, beginning this fall. This was met with mixed reactions from the public.

“I think that given that we don’t have a real emergency on our hands with respect to breakthrough hospitalizations in the sense of we’re not having hospitals overflowing, it would be very wise to study what we should actually do, rather than guessing,” Faust said.

The World Health Organization (WHO) criticized the move and called for a moratorium on booster shots until the world reached vaccine equity. Many health experts are also cautioning against it because of a lack of evidence that it’s necessary.

Faust explained why he is apprehensive about widespread distribution of booster shots until the overall vaccination rate in the U.S. increases more.

“I think that Delta is an uncomfortable development because it makes it much worse for people who have no protection who were unvaccinated, and it causes more breakthrough cases than any other variant has in the past,” Faust said. “And a small subset of those people do have severe illness. The question is what to do about it. And I’m not convinced that boosting everybody is actually what’s necessary given the numbers that I’ve been crunching.”

Last month, Israel began administering a third dose of the Pfizer vaccine among those ages 60 and up, and found that it offered 5-6 times greater protection against serious illness and hospitalization after 10 days.

Nevertheless, "I don’t think that we would expect that boost to suddenly render everyone impervious to infection forever,” Faust said. “Again, it seems like a bandaid now. If you’re a very small country with a limited hospital capacity, that might be worth doing but you can only do it so often in terms of younger people. We really need to know what the benefit added is from the booster because the vaccine already provides tremendous protection against severe illness and worse.”

There are three COVID-19 vaccines currently available in the U.S. Pfizer (PFE)’s is 95% effective at preventing serious illness and death, though these numbers are lessened by the Delta variant, the vaccine from Moderna (MRNA) is 94.1% effective, while Johnson and Johnson (JNJ)’s is 86% effective.

Crowds take streets during
Crowds take streets during "Freedom Rally" to protest COVID-19 vaccination mandate in New York City on September 4, 2021. (Photo by Tayfun Coskun/Anadolu Agency via Getty Images) (Anadolu Agency via Getty Images)

“We now know that the vaccine also decreases long COVID,” Faust said. “So what is a third dose going to do to young people? And we’d like to know if a third dose has any side effects that really start to crop up. After the first dose, we had a couple of side effects, small numbers in young people, [and] after the second dose it went up. Will a third dose make it go further, or is it so far in time spaced away? That is more like the first dose — we don’t know. It’s a bad thing to just roll it out and see.”

For now, according to Faust, the key is to return to stopping the spread with proper social hygiene until vaccination rates improve.

“Until we have everyone vaccinated, we need to try to limit spread,” Faust said. “I think there’s been so much conversation about boosting that we’ve kind of forgotten about the basic things, which is to slow this down until everyone is fully protected."

Adriana Belmonte is a reporter and editor covering politics and health care policy for Yahoo Finance. You can follow her on Twitter @adrianambells and reach her at


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