New variants of the coronavirus are gaining momentum and are drawing attention as a potential threat in the late fall and winter, a development that could reverse recent promising infection trends and has doctors renewing their urging for residents to get up to date on vaccinations.
XEC, which was first detected in Germany, is gaining traction in Western Europe, said Dr. Elizabeth Hudson, regional director of infectious diseases for Kaiser Permanente Southern California. Like nearly all coronavirus strains that have emerged in the past few years, XEC is a member of the widespread Omicron family and is a hybrid of two previously documented variants, KP.3 and KS.1.1.
Past surges in cases “have tended to move from Western Europe to the East Coast and then the West Coast of the U.S.,” Hudson said, “so if we’re seeing more and more cases as we get closer to the colder months, maybe this is a variant that’s likely to take hold.”
XEC is not yet widely seen across the country. According to the US Centers for Disease Control and Prevention, KP.3.1.1, a descendant of the FLiRT variant, is the predominant strain circulating nationwide. In the two weeks ending September 14, KP.3.1.1 was estimated to account for 52.7% of coronavirus samples in the country.
Meanwhile, XEC is not yet tracked on the CDC’s variants website. To qualify as a sub-variant, it must account for an estimated 1% or more of coronavirus cases nationwide.
But Dr. Peter Chin-Hong, an infectious disease expert at the University of California, San Francisco, said it’s estimated that 13% of coronavirus samples in Germany and 7% in the UK are XEC.
“We’ll have to wait and see how things go. If this does start to become an epidemic, we’ll probably start to see it around November or December,” Hudson said. “After Halloween, the weather will probably get definitely cooler and people will start to stay inside more often, and that’s when we’ll likely start to see this outbreak.”
A fall or winter resurgence, which has become a sure thing since COVID-19 emerged, would follow a long summer surge that surprised doctors and experts with its strength.
But one silver lining is that given the timing and strength of the COVID-19 outbreak over the summer, it could probably be two to three months before many people become susceptible to reinfection, Chin Hong said.
The peak of COVID-19 in California last winter, in terms of virus levels in wastewater, was the first week of January.
The Centers for Disease Control and Prevention (CDC) said Friday that after an unexpected summer surge, coronavirus cases are declining or on the decline in 22 states, including California and Texas, and the District of Columbia.
Twenty-two other states, including Florida and New York, have stable or uncertain COVID trends; New Jersey, Washington and Massachusetts have COVID expanding or probably expanding; and three remaining states have no data.
Still, many parts of the country are still seeing relatively high numbers of new coronavirus cases. The Centers for Disease Control and Prevention said Friday that 40 states, including California, Texas, Florida, Illinois, Pennsylvania and Ohio, still have “high” or “very high” levels of coronavirus in their wastewater. Six states, including New York, Michigan, Nevada and Hawaii, are classified as “low” or “minimal.”
In Los Angeles County, coronavirus indicators are trending downward. For the 10 days ending Sept. 7, the most recent days for which figures are available, coronavirus concentrations in sewage were 56% of last winter’s peak. That’s down from the 10 days ending Aug. 24, when virus concentrations were 75% of last winter’s peak.
The average number of coronavirus cases reported in the week ending September 15 was 239 per day, down 31% from the previous week. Officially reported coronavirus cases are an undercount because they don’t take into account tests done at home or the fact that many people don’t get tested when they’re sick. But the trends are still useful in determining how the COVID wave is progressing.
The percentage of emergency room visits in Los Angeles County classified as coronavirus-related was 2.8% in the week ending September 15, down from 3.5% the previous week.
But the average number of COVID-19 deaths is rising, an expected development given the rapid increase in cases and delays in reporting deaths. Los Angeles County reported an average of 4.9 COVID-19 deaths per day in the week ending August 27, up from 4.3 the previous week.
Levels of coronavirus in sewage in the San Francisco Bay Area are also beginning to stabilize. Levels are considered to be moderate at wastewater treatment plants in San Jose and Palo Alto, and low in Sunnyvale and Gilroy, according to the Santa Clara County Public Health Department.
The percentage of positive COVID-19 tests in California has been declining: In the week ending September 16, 8.9% of reported COVID-19 tests (usually conducted in health care settings) returned positive results. The seasonal peak was 12.8% in the week ending August 10, according to the latest data.
It’s still unclear how bad this winter’s respiratory virus season will be: COVID-19 isn’t the only virus of concern, health officials are also closely monitoring influenza and respiratory syncytial virus (RSV).
The CDC predicted in late August that this year’s fall and winter season will be similar to last year’s or slightly weaker, but the agency warned that this forecast could be too optimistic if some assumptions turn out to be wrong, such as fewer people getting vaccinated than expected.
Chin Hong said the situation may improve because people may still have immunity to influenza and respiratory syncytial virus (RSV) outbreaks over the past few winters, and the widespread availability of the RSV vaccine since last year has also helped.
Still, winter always brings with it the risk of respiratory illnesses, such as the risk of a different strain of influenza than the one in the vaccine circulating, which could weaken the vaccine’s effectiveness.
And winter experience in parts of the Southern Hemisphere suggests that a more active respiratory virus season could be on the way here, Hudson said.
“Australia has seen the flu season pretty early and pretty strong. We’re already starting to see some flu cases in the United States, but it’s pretty early on,” Hudson said.
The CDC recommends that everyone 6 months of age or older receive up-to-date COVID-19 and influenza vaccines. Vaccinations are widely available, and the best time to get vaccinated is in September and October, the CDC says.
According to the CDC, you may consider waiting three months after being infected with the coronavirus before getting the latest COVID vaccination, but you can also choose to get vaccinated as soon as you feel better.
“I’m always hopeful, and if people get vaccinated — now is a great time to get the flu shot, get the COVID vaccine — we may be able to reduce the typical spread that we see in the fall and winter, but we don’t know yet how bad it’s going to be,” Hudson said.
Getting vaccinated “means fewer sick days and more time to spend with loved ones. The more protection we have against respiratory illnesses, the stronger we are,” California Surgeon General Dr. Tomas Aragon said in a statement.
Officials say older people and those with compromised immune systems who haven’t been vaccinated for more than a year are at highest risk for severe illness and death from COVID-19.
Data shows that people who received the updated COVID vaccine last year were 54% less likely to become infected between mid-September and January 2023, according to the CDC.
According to the CDC, getting the flu vaccine that’s right for the circulating strain can reduce your chances of getting a flu illness severe enough to require medical attention by 40 to 60 percent.
There are needle-free ways to get the flu vaccine. FluMist, for example, has been available for years as a nasal spray for non-pregnant people ages 2 to 49. On Friday, the US Food and Drug Administration approved FluMist for at-home use, meaning adults can vaccinate themselves and their children.
The at-home option will still require a prescription and is expected to be available from fall 2025.
According to the CDC, COVID remains a greater public health risk than influenza. At least 55,000 COVID-19 deaths have been reported nationwide since October 1. At least 25,000 influenza deaths are estimated during the same period. Influenza death estimates will be updated in October or November.
The CDC recommends the RSV vaccination for all adults age 75 and older, and for people ages 60 to 74 who are at high risk for severe illness. However, the RSV vaccine is not given annually, so people who got it last year do not need to get it again at this time of year.
Pregnant women between 32 and 36 weeks of pregnancy can also receive the RSV vaccine to give protection to the fetus. RSV antibodies are also available for infants and some young children.
The U.S. Department of Health and Human Services has again announced four free COVID tests available by mail for households to sign up for starting at the end of September at covidtests.gov.
In addition to getting vaccinated, California health officials urge people to take steps to prevent getting sick and spreading the virus to others, including staying home when sick, getting tested for COVID-19 or the flu if sick, wearing a mask in public indoor spaces, washing your hands, covering your mouth when coughing or sneezing, and ventilating indoor spaces.
