New subvariants, family reunions may bring more Covid-19 after holidays, but experts don’t expect big surge



CNN

As millions of Americans travel to reunite with friends and family over the coming days, chances are Covid-19 will follow.

Experts expect Thanksgiving gatherings to stir up social media and give new coronavirus subvariants new pockets of vulnerable people to infect. As a result, cases and hospitalizations may increase after the holidays, as they have for the past two years.

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

“We have seen, in some areas, RSV numbers are starting to drop. The flu numbers are still on the rise. And we are concerned that after the holiday gathering, a lot of people will come together, that we may also see an increase in Covid-19 cases, ”said Dr. Rochelle Walensky, director of the States Centers for Disease Control and Prevention on Tuesday. States on CNN.

But things have been relatively calm on the Covid-19 front. Experts say it might not stay that way for long.

“Covid positivity is increasing,” said Shishi Luo, associate director of bioinformatics and infectious diseases at genetic testing company Helix, which monitors coronavirus variants. “It is among 18-24 year olds that it increases the fastest” in the Helix sample.

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

When test positivity increases, it means a greater proportion of Covid-19 tests are returning positive results, and this may indicate that transmission is increasing.

“We should expect more cases,” Luo said. “I don’t know if they’re measured in the way we’re measuring cases right now, but I think in general you should be seeing more sick people. I definitely am.

The rise in cases may not be detected as quickly by official tallies, as people are mainly testing for Covid-19 at home and not reporting their results – if they test at all.

The BQ subvariants of Omicron have risen to dominate transmission in the United States. BQ.1 and its branch BQ.1.1 are descendants of BA.5; they have five and six key mutations in their spike proteins, respectively, that help them evade immunity created by vaccines and infections. Due to 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 Covid-19 cases in the United States. But so far they have achieved dominance without much impact.

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

Nobody knows exactly what will happen with the BQ variants. Many experts say they hope we don’t see the big waves of winters past – certainly nothing like the original Omicron variant, with its jaw-dropping spike of almost a million new daily infections.

There are reasons for optimism on several fronts.

First, there is the experience of other countries like the UK, where BQ.1 has outstripped rivals to dominate transmission even as cases, hospitalizations and deaths have fallen. 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.

“Cases increased in France and Germany just before the subvariants arrived. Then the subvariants arrived and the cases actually dropped,” he said.

Bill Hanage, an epidemiologist at the Harvard TH Chan School of Public Health, thinks our behavior and social contacts might be more important determinants of whether cases will increase this round than whichever variant leads the way.

He thinks it’s likely we’ll see an increase in cases which could peak around the second week of January – as has been the case in recent years – but that won’t have a big effect 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 total number of Covid-19 cases,” he said.

All this does not mean that BQ.1 and BQ.1.1 will have no impact. They showed marked resistance to the antibodies available to protect and treat those vulnerable to severe Covid-19 infections. From this perspective, there are good reasons for people to be cautious if they have a weakened immune system or are around someone who does.

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

“With a lot of people now being boosted and vaccinated and with people having some immunity to an Omicron infection, it’s also a very, very different type of demographic landscape for a variant to emerge,” he said. he declares. “All the signs are, I think, the best part of the scenario in terms of not seeing these massive increases in cases.”

If there is reason to be concerned about BQ in the United States, it could be this: Americans are not as well vaccinated or boosted as other countries. CDC data shows that two-thirds of the population have completed the primary round of Covid-19 vaccines, and only 11% of those who are eligible have received an updated bivalent booster. In the UK, 89% of the population over 12 have completed their primary series and 70% have been boosted.

New research indicates that a country’s vaccination rate matters more than any other factor when it comes to the effects of variants on a population.

Los Alamos National Labs scientists recently completed a study exploring what caused the effects of 13 dominant variants of the coronavirus as they transitioned from one to another in 213 countries. The study includes data through the end of September and was published in preprint form ahead of peer review.

Of the 14 variables that influenced the speed and height of new waves of Covid-19, the vaccination rate of a population was by far the most important.

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

The number of other variants in the mix when a new one emerges is also an important factor, says the study’s lead author, Bette Korber, a lab researcher with the Theoretical Biology and Biophysics Group at Los Alamos.

She points out the Alpha variant, B.1.1.7, and how it fared in the UK compared to the US.

“When he went through England it was just extremely fast, but it was much slower in the Americas,” Korber said.

By the time Alpha reached the United States, we were developing our own variants from California and New York “which were very distinctive and had a competitive advantage over what they faced in England,” said Korber, which probably slowed his roll here.

The CDC is tracking a soup of more than a dozen Omicron subvariants that are causing cases in the United States, and this variety could end up helping to dampen any surge over the winter.

But Korber makes no predictions. She says it’s just too hard to know what’s going to happen, pointing to Asia as the source of her uncertainty.

Asian countries have been facing waves driven by recombinant XBB, a sub-variant that really hasn’t had much of a presence in the United States. The BQ variants came later, but she says they look impressive against XBB, which is also very immune.

“BQ is really taking a stand there,” Korber said. “So I think it’s not really possible yet to be certain” of what might happen in the United States.

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

“Now is the time to be a little more cautious to prevent this wave that we don’t want to see happen, or at least make it a smaller bump,” Korber said.

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