The United States may be headed for a rough flu season, with a virus that causes more severe symptoms than the one last year and seems to be spreading more rapidly and earlier than usual.
On Friday, one day after they returned to work from the government shutdown, scientists at the Centers for Disease Control and Prevention posted data suggesting that flu infections are still low but rising in 39 states.
The dominant flu virus this year, H3N2, is known to cause more severe symptoms than the H1N1 virus that was most common last year. And over the summer, H3N2 acquired at least seven mutations that allow it to sidestep immunity against infection.
Even so, the flu vaccine will help prevent hospitalizations, with an effectiveness of 70 to 75 percent in children and 30 to 40 percent in adults, according to data from the Health Security Agency in Britain.
“It is absolutely clear that the vaccine may not stop people getting infected with the new variant,” said Derek Smith, a flu expert and director of the Center for Pathogen Evolution at Cambridge University. But it “will still help to protect against severe disease,” he said.
Covid rates are rising or holding steady in many states, but the rates of hospitalization remain very low. The C.D.C. did not provide an update on a third seasonal disease, respiratory syncytial virus, or R.S.V., but other trackers have found the rates are climbing slowly, with hospitalizations rising among children under 5.
Flu seasons in the United States tend to mimic the patterns in the Southern Hemisphere winter earlier in the year. This year, Australia experienced the worst flu season in its history.
Now, in the Northern Hemisphere, Britain’s flu season began a month earlier than usual, with cases triple the same time last year. The country’s National Health Service issued a “flu jab SOS,” urging people to get vaccinated immediately. In Japan, the Tokyo municipal government issued its first flu warning since 2009. As of Nov. 9, more than 1,100 schools in the city had closed, compared with 99 at the same time last year.
Although flu rates in the United States are low, public health experts said that may quickly change, especially as multigenerational families gather for the holidays.
“We’re likely a few weeks out from things getting really serious, and that means now is the time to get vaccinated, because it takes a couple of weeks for full protection,” said Sam Scarpino, a public health expert at Northeastern University.
So far at least, overall vaccination rates for respiratory diseases in the United States remain low. Most doses at Walgreens pharmacies have been given to adults 55 and older, and more than half to those who are 65 and older.
“We’re seeing a pretty low uptake in other age ranges,” said Rick Gates, chief pharmacy officer for Walgreens, which has expanded its respiratory disease tracker.
Even if older adults and young children are protected with vaccines, they may remain at risk if other family members don’t get the shots and bring home the virus, he said.
Studies have shown that digital reminders, like emails, texts and social media posts, can boost immunization rates. But in February, in the throes of last year’s severe flu season, the Trump administration canceled the C.D.C.’s flu vaccination campaign, which depicted a tiger and a kitten to convey that the shots can turn flu from “wild” to “mild.”
Andrew Nixon, a spokesman for the Department of Health and Human Services, which oversees the C.D.C., said the C.D.C. had replaced that campaign with another one that delivers messages about preventing respiratory diseases “to reach people where they are — online, in their communities, and through trusted health partners.”
“C.D.C. continues to recommend flu vaccination since past data suggest vaccination can reduce severity of illnesses,” Mr. Nixon said.
But “the decision to vaccinate is a personal one,” he added. “People should consult with their health care provider to understand their options to get a vaccine and should be informed about the potential risks and benefits associated with vaccines.”
Dr. Fiona Havers, who led the C.D.C.’s respiratory disease data efforts before resigning in June, said she feared the administration’s rhetoric and watered-down recommendations were reducing confidence in vaccines.
“The way that vaccines have been talked about means that we’ll see decreasing rates of vaccination in high-risk populations, and potentially more vaccine-preventable deaths,” she predicted.
The C.D.C. estimates that last year, flu was associated with at least 38,000 deaths, 279 of them in children. Since collection of the data began in 2004, the number of pediatric deaths was the highest reported in any influenza season outside of the swine flu pandemic in 2009.
In children, flu infections can also lead to rare complications, including brain damage and heart problems.
Scientists in Britain estimated that the new variant, called H3N2 subclade K, has a reproduction number of 1.4 — meaning that each infected person would spread the virus to 1.4 others on average. (The C.D.C. estimates that the virus is spreading at similar rates in many states.) Seasonal flu typically has a reproduction number closer to 1.2; the higher number this year could translate to millions of additional cases.
“There are very clear signals that it’s going to sweep the world, and it’s going to sweep the world quickly,” Dr. Smith said of the variant.
The mutations the virus acquired this summer — well after the composition for this year’s vaccine was chosen — may partly be the reason for its rapid spread. But it’s too early to say whether the mutations also make H3N2 more virulent.
“We know the numbers are likely to be higher than usual, but we don’t yet know how nasty it is,” Dr. Smith said. Those data will be available in a few weeks, he said, as the virus makes its way from children to older adults.
Apoorva Mandavilli reports on science and global health for The Times, with a focus on infectious diseases and pandemics and the public health agencies that try to manage them.
The post Early Signs Point to a Harsh Flu Season in the U.S. appeared first on New York Times.
