COVID concern

MARY REICHARD, HOST: Next up on The World and Everything in It, the delta variant of Covid.

While many countries are renewing their coronavirus lockdowns, Americans almost appear to be living in a bubble. Airports are packed. Shopping centers are bustling, and plates and dishes are clanking in restaurants across the country. With new cases at their lowest level since March of 2020, America is returning to normal.

NICK EICHER, HOST: But the extraordinarily infectious delta variant, which is wreaking havoc overseas, is now spreading in the United States. And some projections say the variant, first discovered in India, will soon be the dominant strain here.

REICHARD: So what is the state of America’s COVID recovery? And could the delta variant threaten it?

Here now to discuss is Dr. Chris Lindsell. He is a professor of Biostatistics and Biomedical Informatics at Vanderbilt Univ. Medical Center. Dr. Lindsell, good morning!

CHRIS LINDSELL, GUEST: Good morning. Thank you for having me.

REICHARD: Well, let’s start with a snapshot of where we are right now as compared to the start of this pandemic. Talk about new infections and death rates as between then and now?

LINDSELL: It's a very good question. The actual numbers are interesting and tell a story that is very different to the emotional and behavioral story that is being told on the ground. The numbers look as though we have substantial numbers of deaths still, and considerable numbers of infections. And yet the social and behavioral changes on the ground are very different. And in part I think it is because the American public in general are thinking a little bit differently about the pandemic. And they're seeing a decline in the cases from its peak, and they're not doing comparison against baseline. If we were to compare against baseline, we would realize that we still have a raging pandemic locally as well as globally.

REICHARD: A little under 60 percent of U.S. adults are now fully vaccinated. When we combine those who are vaccinated with those who are not but have prior infection … could we be getting anywhere close to the threshold for herd immunity?

LINDSELL: There are several things at play in this particular issue. The first is understanding how much immunity is conferred by an infection. We believe that being infected does result in some level of immunity. However, not all people who've been infected have the same level of immunity. And so we're just beginning to work through how infection and vaccination combined within an individual for immunity of the person. But as you say, we have a very large proportion of people who have been vaccinated or who've been infected. And so the underlying question of are we approaching herd immunity, again, it's a little bit difficult to answer the question truly because even if 80% of the population in one part of the United States were to be vaccinated, there are other parts where the vaccination rate is much, much lower. And so we will see across the country some areas where they may be achieving this herd immunity level and in other areas where the vaccination rates are low and herd immunity is really out of reach. So, across the country, some areas have already achieved it. Other areas are going to be a long, long way behind. But overall, in terms of the people who've been infected, whether or not they contribute to the herd immunity, we're just beginning to work that out and how much immunity they have.

REICHARD: So, the original strain that took hold in the United States is now a relatively small percentage of new infections, multiple variants have overtaken it. The delta variant is the one that’s now on the rise, and some experts are concerned about this. How effective are the U.S. vaccines against this variant? And should we be concerned about this strain?

LINDSELL: The data that we currently have on hand suggests that the vaccines we have are effective against the Delta variant. Precisely how effective and whether they’re as effective against the Delta variant as others, we're still unclear. But the data do suggest—and there was a publication late last week that really points at this—that there is a good vaccine effectiveness against the delta variant. Should we be concerned about it? We should be concerned about it the same way we're concerned about COVID itself. The Delta variant has much greater transmissibility and so passing between people is high. And so yes, I think we should be concerned about the Delta variant. It spreads quickly and it is dangerous. And even though the vaccines do appear to be effective against it, if you're unvaccinated, or you happen to be one of the unlucky people that has a breakthrough case, we should be worried about the Delta variant.

REICHARD: Health officials in India are voicing concern about a strain mutated from the delta variant. Can you tell us anything about that mutation?

LINDSELL: I don't have information on that particular mutation at this time. I do hear a rumor—and I will emphasize that it is rumor—that the mutations may be less susceptible to the vaccines. But again, I've seen no data to confirm that. However, in any pandemic, one should always be concerned about the new variants and the evolution of the virus, because there's always the potential that it will out evolve the pace of technology and the pace of medicine.

REICHARD: Okay, Dr. Chris Lindsell has been our guest. Dr. Lindsell, thanks so much!

LINDSELL: Thank you very much, Mary.

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