New subvariants, family gatherings may bring more Covid-19 after the holidays, but experts do not expect a significant increase



CNN

With millions of Americans traveling to visit friends and family in the coming days, there’s a good chance Covid-19 will follow.

Experts expect the Thanksgiving gatherings to stir up social media and provide new pockets of vulnerable people to infect new sub-variants of the coronavirus. As a result, cases and hospitalizations may increase after the holiday, as in the past two years.

Covid-19 is not unique in this respect. Thanksgiving gatherings also have the potential to increase the spread of other viruses, especially respiratory syncytial virus, or RSV, and influenza, which are already at high levels this time of year.

“In some regions we have seen RSV numbers start to drop. The number of flu cases continues to rise. And we fear that after the holiday gathering, a lot of people will gather, that we may see an increase in cases of Covid-19 as well,” said Dr. Rochelle Walensky, director of the US Centers for Disease Control and Prevention.

But things have been relatively quiet on the Covid-19 front. Experts say it won’t stay that way for long.

“Covid positivity is rising,” said Shishi Luo, deputy director of bioinformatics and infectious disease at genetic testing company Helix, which monitors variants of the coronavirus. “Growing fastest among 18- to 24-year-olds” in the Helix sample.

This is the first time that test positivity has increased in Helix’s data since July.

When test positivity increases, it means that a greater proportion of Covid-19 tests are positive and may be a sign that transmission is on the rise.

“We should expect more cases,” Luo said. “I don’t know if it’s measured by how we’re measuring cases right now, but in general I think you should see more sick people.” I definitely am.”

The increasing cases may not be captured as quickly by the official numbers because people mostly test for Covid-19 at home and do not report their results – if they test at all.

The BQ Omicron sub-variants grew to dominate US transmission. BQ.1 and its offshoot BQ.1.1 are descendants of BA.5; they have five and six key mutations in their top proteins that help them escape the immunity created by vaccines and infections. Because of these changes, they grow faster than BA.5.

For the week ending November 19, the CDC estimates that BQ.1 and BQ.1.1 caused about half of all new cases of Covid-19 in the US. But so far they have gotten the upper hand without much impact.

COVID-19 cases, hospitalizations and deaths have been flat for the past four weeks. But it’s not gone: On average, more than 300 Americans die and 3,400 people are hospitalized with Covid-19 every day, according to CDC data.

No one knows exactly what will happen to the BQ variants. Many experts say they hope we don’t see past big waves of winters — certainly nothing like the original Omicron variant, with its declining peak of nearly a million new infections a day.

There is reason for optimism on many fronts.

First, there is experience from other countries, such as the UK, where BQ.1 outperformed its competitors and controlled transmission, even as the number of cases, hospitalizations and deaths fell. Something similar happened in France and Germany, notes Michael Osterholm, an infectious disease expert who directs the Center for Infectious Disease Research and Policy at the University of Minnesota.

“The cases appeared in France and Germany just before the subvariants appeared. Then the subvariants came and the cases really went down,” he said.

Bill Hanage, an epidemiologist at the Harvard TH Chan School of Public Health, thinks that our behavior and our social contacts may be bigger determinants of whether the number of cases will increase in this carousel than any variant that is in charge.

He thinks it’s likely we’ll see a spike in cases that may peak around the second week of January — as it has in past years — but that it won’t have a big impact on hospitalizations and deaths.

Andrew Pekosz, a virologist at the Johns Hopkins Bloomberg School of Public Health, says that’s likely because the benefits of BQ.1 are gradual, not drastic.

“It probably has a bit more of a fitness advantage, so what we’re seeing is a gradual replacement without a massive change in the overall number of Covid-19 cases,” he said.

This does not mean that BQ.1 and BQ.1.1 will have no impact. They have shown significant resistance to antibodies that are available to protect and treat people who are susceptible to severe Covid-19 infections. From this point of view, there is good reason for people to be careful if they have a weakened immune system or are around someone who does.

But these subvariants land at a time when population immunity is higher than ever thanks to vaccines and infections. It’s a very different setup than the virus encountered when Omicron emerged a year ago, and it should also help dampen any coming wave, Pekosz says.

“With many people now being boosted and vaccinated, and with people having some immunity to Omicron infection, it’s also a very, very different kind of population environment in which a variant can emerge,” he said. “All the symptoms are, I think, the best part of the scenario in terms of not seeing these massive increases in cases.”

If there’s a reason to worry about BQ in the US, it might be this: Americans aren’t as well vaccinated or fortified as other countries. CDC data shows that two-thirds of the population has completed the primary series of Covid-19 vaccines, and only 11% of those eligible have received the updated bivalent booster. In the UK, 89% of the over 12 population completed the core series and 70% were boosted.

New research shows that a country’s vaccination coverage matters more than any other single factor when it comes to population effects of variants.

Scientists at Los Alamos National Labs recently completed a study that delved into what caused the effects of 13 dominant variants of the coronavirus as they transitioned from one to another in 213 countries. The study covers data up to the end of September and was published as a pre-print prior to peer review.

Among the 14 variables that affected the speed and height of new waves of Covid-19, population vaccination coverage was by far the most important.

The number of previous cases in a given country, the percentage of people who wore masks, the average income and the percentage of the population over 65 ranked second, third, fourth and fifth respectively.

How many other variants are in the mix when a new one emerges is also an important factor, says lead study author Bette Korber, a laboratory scientist in the Theoretical Biology and Biophysics Group at Los Alamos.

He points out the Alpha variant, B.1.1.7, and how it fared in the UK versus the US.

“When it went through England it was extremely fast, but in America it was much slower,” Korber said.

Before Alpha arrived in the United States, we were developing our own variants out of California and New York, “which were very distinctive and had a competitive edge over what she had to deal with in England,” Korber said, which probably slowed it down. his role here.

The CDC is tracking the soup of more than a dozen Omicron subvariants that cause cases in the U.S., and this variety may eventually help dampen any surge over the winter.

But Korber makes no predictions. He says it’s too hard to know what will happen and points to Asia as the source of his uncertainty.

Asian countries are dealing with waves driven by recombinant XBB, a subvariant that has not been widely represented in the United States. The BQ variants arrived later, but he says they look impressive against XBB, which is also highly immune.

“BQ really stands there,” Korber said. “So I think there’s no way to be sure yet” what might happen in the US.

“For me, it’s a good time to wear masks when possible,” she said. Masks protect the wearer and others around him. “And get a booster if you’re eligible and the moment is right for you,” especially when we gather around the table to feast with our friends and family.

“It’s time to put a little extra caution in place to prevent, or at least mitigate, that wave that we don’t want to see happen,” Korber said.

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