As millions of Americans gather with friends and family over the next few days, Covid-19 will likely follow.
Experts expect Thanksgiving gatherings to stir up social networks and provide new vulnerable populations for the new coronavirus subvariant. 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 exacerbate the spread of other viruses, especially respiratory syncytial virus (RSV) and influenza, which are already at high levels at this time of year.
“We’ve seen RSV numbers start to trend down in some areas. Flu numbers are still going up. We’re concerned that after holiday gatherings, where a lot of people get together, we might see an increase in Covid-19 cases as well. Rochelle Valensky, director of the U.S. Centers for Disease Control and Prevention, said Tuesday on CNN.
But on the Covid-19 front, things have been relatively quiet. That may not last long, experts say.
“Covid positivity rates are rising,” said Shishi Luo, deputy director of bioinformatics and infectious disease at Helix, a genetic testing company that has been monitoring coronavirus variants. In the Helix sample, “the fastest growth was seen among the 18-24 age group”.
It was the first increase in test positivity in the Helix data since July.
When test positivity rates increase, it means a greater proportion of Covid-19 tests are returning positive results, which can indicate that transmission is on the rise.
“We should expect more cases,” Luo said. “I don’t know if they’re measuring it the way we measure cases now, but I think in general you should be seeing more people who are sick. I absolutely am.
Official tallies may not be picking up more and more cases anytime soon because people are mostly testing for Covid-19 at home and not reporting the results – if they do.
Omicron’s BQ subvariant has risen to dominate US transmission. BQ.1 and its clade BQ.1.1 are descendants of BA.5; their spike proteins have five and six key mutations, respectively, that help them evade immunity from vaccines and infections. Because of these changes, they grow faster than BA.5.
For the week of Nov. 19, the CDC estimated that BQ.1 and BQ.1.1 were responsible for approximately half of new Covid-19 cases in the United States. But so far, they have risen to dominance without much impact.
The number of Covid-19 cases, hospitalizations and deaths has remained flat over the past four weeks. But it hasn’t gone away: On average, more than 300 Americans die from Covid-19 every day and 3,400 are hospitalized, according to the CDC.
No one knows for sure what will happen to the BQ variant. Many experts say they hope we won’t see the big waves of this past winter—certainly not like the original Omicron variant, which saw eye-popping spikes in new daily infections.
There are reasons for optimism on many fronts.
First, there is the experience of other countries, such as the UK, where BQ.1 has outpaced its competitors in dominating transmission amid falling cases, hospitalizations and deaths. Michael Osterholm, an infectious disease expert and director of the Center for Infectious Disease Research and Policy at the University of Minnesota, noted that something similar happened in France and Germany.
“Just before the subvariant came along, cases went up in France and Germany. Then the subvariant came in and cases actually went down,” he said.
Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health, thinks our behavior and our social interactions may be a bigger determinant of whether this round of cases will rise, rather than any variant in the lead.
He thinks we’re likely to see an increase in cases, possibly peaking around the second week of January — as we’ve seen in the past few years — but it won’t have a major impact on hospitalizations and deaths.
That may be because the dominance of BQ.1 is gradual rather than dramatic, says virologist Andrew Pekosz of the Johns Hopkins Bloomberg School of Public Health.
“It probably has the advantage of being more adaptive, so what we’re seeing is a gradual replacement without a huge change in the total number of Covid-19 cases,” he said.
This is not to say that BQ.1 and BQ.1.1 will not have any impact. They showed marked resistance to antibodies that can be used to protect and treat people who are vulnerable to severe Covid-19 infection. Viewed in this light, if people have weakened immune systems or want to be around someone with a weakened immune system, they have good reason to be cautious.
But thanks to vaccines and infections, these subvariants will land at a time when population immunity is higher than ever. This is a stark difference from the virus encountered when Omicron emerged a year ago, which should also help dampen any incoming waves, Pekosz said.
“There’s a lot of people now who are getting boosters and vaccinations and people have some immunity to Omicron infection, and that’s also a very, very different population landscape where variants can emerge,” he said. “I don’t think we’re seeing All indications are the best case scenario in terms of a significant increase in cases.”
If there is reason to worry about BQ in the US, it might be this: Americans are not getting vaccinated or boosted as much 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 newer bivalent booster. In the UK, 89% of the 12+ population complete their Junior series and 70% progress.
A country’s vaccination rate is more important than any other single factor when it comes to the impact of variation on a population, new research shows.
Scientists at Los Alamos National Laboratory recently completed a study delving into what drives the effects of 13 major variants of the coronavirus as they move from one variant to another in 213 countries. The study included data through the end of September and was published as a preprint before peer review.
Of the 14 variables influencing the speed and height of new Covid-19 waves, the population’s vaccination rate is by far the most important.
The number of past cases, the proportion of the population wearing masks, the average income and the proportion of the population over 65 years old in a country are far ahead of the second, third, fourth and fifth respectively.
When a new variant emerges, how many other variants are in the mix is also an important factor, said senior study author Bette Korber, a laboratory researcher in Los Alamos’ Theoretical Biology and Biophysics Group.
She points to the Alpha variant B.1.1.7, and how it behaves in the UK and US.
“When it goes through England, it’s very fast, but it’s much slower over the Americas,” Kerber said.
By the time Alpha arrives in the U.S., we’re evolving our own variants out of California and New York, “which are very unique and have a competitive advantage compared to what it encounters in the U.K.,” Korber said, which could slow it down. Scroll here.
The CDC is tracking more than a dozen Omicron subvariants that are causing cases in the U.S., and that variant could eventually help stem any winter tide.
But Kerber didn’t make any predictions. She said it was hard to know what to expect and pointed to Asia as a source of her uncertainty.
Asian countries have been dealing with a wave driven by recombinant XBB, a subvariant that doesn’t have much of a presence in the United States. BQ variants came later, but she said they looked impressive against XBB, which is also highly immune to evasion.
“BQ really stands there,” Kerber said. “So I don’t think it’s really certain” what’s going to happen in the US.
“To me, now is a good time to wear a mask,” she said. Masks protect the wearer as well as others around them. “If you’re eligible and now is the perfect time for you, get your booster,” especially when we’re sitting around the dinner table with friends and family.
“It’s time to be extra careful to prevent that wave that we don’t want to see, or at least make it a little bit smaller,” Kerber said.