Rising COVID-19 cases in Europe are setting off warnings that the U.S. could experience a new surge this winter. 

Previous jumps in the U.S. have followed a pattern in which cases first rise in Europe, making officials nervous they could see a spike in U.S. cases as the weather turns.  

The most recent data from the European Centre for Disease Prevention and Control shows that cases began going up around the beginning of September in Europe.  

The seven-day average is roughly 230,000 cases per day, reflecting rates that were seen in late July when Europe was still dealing with the omicron BA.4/BA.5 subvariant wave. 

World Health Organization Director-General Tedros Adhanom Ghebreyesus stated last week that a rise in cases in Europe was expected due to cooling temperatures, but stressed that hospitalizations and deaths did not have to rise as well due to the viral therapeutics that are now available. 

Confirmed coronavirus-related deaths across the European Union have remained low, with a seven-day average of 280 as of last week. 

In the U.S., cases and deaths have continued to trend down, but dropping temperatures that push people indoors, dismal booster vaccination numbers and an overall disregard for pandemic mitigation practices are setting the stage for a winter wave resembling the one across the Atlantic. 

The seven-day moving average for cases in the U.S. is around 38,000, while the seven-day moving average for deaths is about 330. 

Ali Mokdad, epidemiologist and professor of Health Metrics Sciences at the Institute for Health Metrics and Evaluation at the University of Washington, told The Hill the contrast in the regions can be attributed to multiple factors, including warmer temperatures in the U.S. and differing levels of community immunity. 

“In the U.S., we have a higher infection rate than many European countries, where more people have been infected here. So we have a little bit more immunity than they do, but still we have waning immunity,” Mokdad said. 

COVID-19 cases, deaths and hospitalizations in the U.S. will likely begin going up in three to four weeks, Mokdad said, though they won’t reach the same levels seen during the omicron wave last winter. He emphasized that this projection is contingent on a situation in which new coronavirus variants that are better at escaping immunity don’t rise in dominance. 

Researchers and virologists have continually stated that the risk of a more infectious variant still looms as the SARS-CoV-2 virus continues to spread and mutate. 

The COVID-19 Scenario Modeling Hub, a U.S.-based data collective operated by researchers and public health experts, publishes possible directions in which the pandemic could go based on multiple models. 

The most recent projections from the data hub present four scenarios: two in which no new variants occur and two in which they do.

Shaun Truelove, assistant scientist at the Johns Hopkins Bloomberg School of Public Health and a member of the COVID-19 Scenario Modeling Hub team, said he is leaning away from the potential scenarios where no new variants arise. 

“We are seeing variants, we are seeing that they are emerging and it seems like we will have one of those,” said Truelove. 

The BA.5 omicron subvariant, the dominant strain in the U.S., has begun losing its foothold in the U.S., with sublineages like BA.4.6 and BQ.1.1 growing in prevalence. In some parts of the Midwest, BA.4.6 now accounts for a fifth of COVID-19 cases. 

The differences in community immunity levels between the U.S. and Europe presents a challenge in projecting where the American infection rates will go based on overseas observations, according to Truelove. 

“We have a situation where people are constantly being infected, so their immunity from that infection or from vaccination is waning. And then at the same time as all that’s happening, we’re also seeing the influx of these new variants that have these immune escape properties,” he said. 

Apart from COVID-19, there are other bits of information that can be gleaned from Europe’s situation that could help forecast what the U.S. will experience in the upcoming months. 

Health officials have warned that the flu will likely be worse than it has been in recent years due to lack of exposure, possibly resulting in a “twindemic” of both viruses. Mokdad noted that a spike of influenza infection in Europe has not yet been observed amid the coronavirus surge. 

“We haven’t seen a spike of cases in Europe right now. … So some encouraging news for the flu, but I wouldn’t bet on it,” said Mokdad. 

While U.S. influenza cases have been rising, only 3.3 percent of lab-tested specimens have come back as positive, according to the Centers for Disease Control and Prevention. Recent polling from the National Foundation for Infectious Diseases found that 49 percent of U.S. adults plan on getting the flu shot this year, only 5 points lower than the percent of adults who got the shot last year.

The prevalence of people getting vaccinated and practicing viral mitigation methods like masking and social distancing has largely fallen out of favor. President Biden said in September that the pandemic was “over,” a move that Mokdad partly cited for the slow booster uptake. 

“President Biden said the pandemic is over, but that’s a mistake for me at a time when we’re trying to push a booster for a new vaccine designed for BA.4 and BA.5 and he goes and says it’s over. So why would people go and get the vaccine?” Mokdad said. “It’s very hard for me to say COVID-19 is over. It’s not over, especially right now coming into winter.” 

Experts who spoke with The Hill strongly encouraged people to get the updated bivalent booster ahead of the holiday season. 

“The best holiday present that you can give — whatever you celebrate — that you give for yourself and your family members is protection and safety. And the best way to do it is to go and get your booster and your flu shot,” Mokdad said.