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What to know about the CDC’s delta variant study and how it affects vaccinated Americans

The World Health Organization said COVID-19 infections are up 80% around the world in the last month, overwhelming health systems in many countries. In the U.S., the Centers for Disease Control and Prevention released a pivotal study showing fully vaccinated people can spread the delta variant as readily as non-vaccinated people. Amna Nawaz gets the details from Brown University's Dr. Ashish Jha.

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  • Judy Woodruff:

    This was a day of sobering and surprising news about how COVID-19 is again accelerating in the U.S. and around the world.

    The World Health Organization said that infections are up 80 percent globally just in the past month, overwhelming health systems in many countries.

    On the continent of Africa, deaths are up 80 percent. Back in the U.S., the Centers for Disease Control made public a pivotal study explaining how fully vaccinated people can spread the Delta variant. The study raises serious questions about how businesses and schools should operate as they reopen.

    Amna Nawaz has the details.

  • Amna Nawaz:

    Judy, the CDC examined a COVID outbreak in Provincetown, Massachusetts, around Fourth of July weekend. Within weeks, that outbreak spread to at least 469 people around the state, a state with nearly 70 percent vaccination rate among adults.

    Three-quarters of those infected had been fully vaccinated. Nearly 80 percent were symptomatic. So far, there have been no deaths, and just five people were hospitalized, but four of them were fully vaccinated. and Provincetown had low levels of virus transmission when the outbreak began.

    In fact, an internal CDC document about the Delta variant obtained by The Washington Post said officials must recognize that — quote — "the war has changed."

    We look at key questions coming out of all this with Dr. Ashish Jha. He's the dean of Brown University's School of public Health.

    Dr. Jha, welcome back to the "NewsHour." Always good to have you here.

    So, people will look at this study, and they will say, look, this tells me, if I'm vaccinated, I can still get the virus, I can still feel sick, I can still transmit it to other people. Why should I get the vaccine?

    What do you say to them?

  • Dr. Ashish Jha:

    Yes. So, Amna, first of all, thanks for having me back on the "NewsHour."

    What I would say is that, actually, this study, looking at what happened in Provincetown, is the vaccines working exactly as we expected. And let me lay out why.

    And what you had was, you had an influx of a lot of people coming to Provincetown for July 4 celebrations, a lot of unvaccinated people, Delta virus surging. You did have a good number of breakthrough infections. Not surprising when you have a lot of people packed into bars and clubs.

    But let's see what happened to those people. Almost all of them did extraordinarily well. A small number ended up in the hospital. No one died. And it did not fuel this massive outbreak that has led to more and more cases in an exponential growth.

    In fact, that outbreak has more or less faded away. Case numbers have declined. Infection numbers are down now. No one died from this, thank goodness. This is the vaccine working.

    So, what I would say people is, vaccines turn what is a potentially deadly disease into a mild one. Your chances of passing it on are much lower.

  • Amna Nawaz:

    Dr. Jha, a lot of people will look at these numbers, though, and say the overwhelming majority of people here were fully vaccinated. Doesn't that say to you that this is actually spreading much faster than we previously thought it was?

  • Dr. Ashish Jha:

    Yes. No, I get that. And that makes some sense to me that people would be concerned about that.

    But you have to remember that underlying population was largely vaccinated. Imagine, if 99 percent of people are vaccinated in the community, then any outbreak will largely happen among the vaccinated.

    So that, to me, is not, unto itself, any kind of indictment of the vaccines. The key is to ask the question, is the transmission happening as badly among the vaccinated? And, most importantly, the question is, are vaccinated people getting sick or not? And we have very clear evidence that the vaccinated people, when they have a breakthrough infection, are not getting sick at the same rates.

  • Amna Nawaz:

    You mentioned the Delta strain.

    Of course, we have heard again and again from officials that it's much more highly transmissible. What else do we know about it? Because I know people have questions. Is it transmitted in the same way, breathing in aerosol particles? So we know anything about transmission by surface or touch?

  • Dr. Ashish Jha:

    Yes, it's still the same virus.

    So the mechanisms are still the same. It's still an airborne disease passed from people to people through breathing. There may be a little bit of surface stuff, but we think it's pretty tiny, not a major source.

    The other thing we know that actually the CDC report highlights is, it does look like, if you get infected with a Delta variant, you're more likely to get sick than from previous variants, so it may be a more severe form of the virus as well. That's not nailed down, but that is of concern. And we have got to really sort that out.

  • Amna Nawaz:

    And that is true whether you're vaccinated or not, correct?

  • Dr. Ashish Jha:

    Well, certainly among the unvaccinated.

    We have not seen a lot of vaccinated people get particularly sick from this. There are going to be a small number who might. So I think, for the unvaccinated, that is largely true.

  • Amna Nawaz:

    So, the CDC did issue new masking guidance this week. They're now saying everyone who's fully vaccinated should wear a mask inside public setting where transmission is high.

    Walmart is now requiring all its workers in high-transmission areas to mask. Broadway is now requiring masks and vaccinations for all members of its audience. Should we, generally speaking, as Americans, be reevaluating indoor activities right now, more broadly speaking?

  • Dr. Ashish Jha:

    Yes, so I think one of the things we have had to do throughout the whole pandemic is make adjustments as the virus has changed.

    I mean, this is an evolving virus. And as the virus evolves, we have got to evolve. Right now, we have a very dangerous, very transmissible variants circulating largely among the unvaccinated Americans.

    I think, if you're in a hot zone with a lot of infections, it makes sense to potentially wear a mask indoors. I think it makes sense to avoid large crowded indoor gatherings like nightclubs and super packed restaurants.

    That isn't necessarily the policy I'd have for every part of the country. But for those hot zones, I think that's pretty reasonable.

  • Amna Nawaz:

    So, you mentioned this new strain of the Delta variant we are talking about.

    There was a World Health Organization official, Maria Van Kerkhove, who was asked about potential new variants of the virus ahead. Take a listen to what she had to say.

  • DR. MARIA VAN KERKHOVE, World Health Organization:

    There will be more. And it's in the virus' interests. Viruses are not alive, so they don't have a brain to think through this. But they become more fit the more that they circulate. And so the virus will likely become more transmissible, because this is what viruses do. They evolve. They change over time.

  • Amna Nawaz:

    Dr. Jha, what are the chances we're dealing with another variant sometime later this year?

  • Dr. Ashish Jha:

    We might. We might.

    I mean, look, the — all of the variants we have seen so far have come out of countries where there were large outbreaks. There are large outbreaks still happening around the world because we haven't gotten vaccines out to the world.

    So, as long as that happens, I think we should be ready for more variants. Whether they will necessarily be much more contagious, or maybe they will — whether they will evolve our immune system and our vaccines, I don't know.

    But I'm pretty hopeful that, if we can keep plugging away on vaccinations, we can put this to an end. But we definitely have to pay close attention to that possibility there.

  • Amna Nawaz:

    And I have to ask you. A lot of people we talk to say that they're confused and frustrated, quite frankly, by the way the CDC has been messaging some of the guidance over the last year-and-a-half. They feel like it's shifted and changed.

    You and I have talked about it before. We have said, as the science evolves, as you know more, that guidance does change. But what do you think the CDC needs to do now to make sure this guidance sticks at this latest turn in the pandemic?

  • Dr. Ashish Jha:

    Yes, so what I think the CDC needs to do is explain, first of all, how it makes its decisions, and the fact that, when new data comes in, we want the CDC.

    I mean, as a physician, when I — when new studies are done on the way to treat a patient, I changed my clinical practice. That's actually normal. And that's what we want CDC to do. But we try — the CDC to do a better job of explaining it. And, by the way, the CDC should make its data more apparent and transparent.

    They shouldn't say we have data, but we can't share it. That, I think, breeds some amount of confusion in people.

    I think the CDC should also tie these guidance to clear metrics, so that people understand that, when infection numbers go down, the masking guidance will change. That's what we want. We want to be flexible, we want to be data-driven, and we want the CDC to help guide us in that process.

  • Amna Nawaz:

    And we want people to stay as safe as they possibly can.

    That is Dr. Ashish Jha, dean of Brown University's School of Public Health.

    Always good to have you. Thank you for your time.

  • Dr. Ashish Jha:

    Thank you.

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