The flu continues to wreak misery across the United States, with all but four states showing high or very high levels of activity as a new virus strain called subclade K continues to spread.
By another measure — visits to the doctor for a fever accompanied by a cough or sore throat, which are common flu symptoms — the United States is at its highest level of respiratory illnesses since at least the 1997-98 flu season, according to data released Monday by the U.S. Centers for Disease Control and Prevention.
“It’s definitely a banner year,” said Dr. Caitlin Rivers, an epidemiologist and senior scholar at the Johns Hopkins Center for Health Security. “This is the worst we’ve seen in at least 20 years. We’re seeing a majority of the country experiencing very high levels of activity, and we’re still in the thick of it.”
It’s striking to see such an intense season following last year’s bad flu season, she noted, because bad years don’t usually come back to back.
Nationally, about 8.2% of doctor visits were for flu-like symptoms in the last week of the year. At the same time last season, which was also dynamic, this figure was 6.7%.
In Massachusetts, which is reporting very high levels of flu activity, health officials have urged people to get vaccinated.
“This is a moment of clarity, urgency and action,” Public Health Commissioner Dr. Robbie Goldstein said in a news release. “These viruses are serious, dangerous and potentially deadly. We see children seriously ill, families grieving devastating losses and hospitals under pressure.
“There is a simple, effective and available way to address these concerns: vaccines,” he added. “They can prevent serious illness and hospitalizations. And they save lives. If you haven’t yet gotten your flu or COVID-19 vaccine this season, now is the time. It’s not too late. Choosing vaccination is choosing to protect yourself, your family, your friends, your colleagues and your community.”
Nearly all U.S. states had high or very high levels of flu activity in the latest data. Montana and Vermont reported low levels of activity, while South Dakota and West Virginia reported moderate levels. Nevada did not report flu data this week, but showed high levels of flu activity in last week’s report.
In terms of severity – how many people have been hospitalized with the flu – this season is not yet exceptional. The cumulative hospitalization rate is the third highest at this point in the season since 2010-11, but that could change as more people become infected.
“In the next 48 hours, if you haven’t been vaccinated, get vaccinated. Don’t wait,” said Dr. Michael Osterholm, who directs the Center for Infectious Disease Research and Policy at the University of Minnesota. “You know, you might still be able to protect yourself against the latter parts of the seasonal outbreak, but you know, it takes us seven to 10 days to develop some immunity to the vaccine, and so you don’t have a lot of time to waste,” he added.
The CDC estimates that at least 11 million people have had the flu this season, 120,000 have been hospitalized and 5,000 people have died.
The agency also received another report of the death of a child, bringing the total number of children who have died from the flu this season to nine.
Flu vaccinations have declined among children, from a high of 53% during the 2019-20 flu season to 42% at the same time this season.
The new flu data came on the same day the U.S. Department of Health and Human Services announced a plan to change the childhood vaccination schedule. The changes would recommend that children get flu shots after a consultation with a health care provider, an arrangement called shared clinical decision-making, which could make vaccines more difficult for people to access.
“To withdraw a flu recommendation in the middle of a pretty serious flu year seems pretty tone-deaf to me, and this is coming from a flu year where we’ve had the highest number of childhood deaths from flu in many years,” said Dr. Sean O’Leary, chair of the American Academy of Pediatrics’ infectious diseases committee.
Shots are also down among adults, from nearly 61 million in 2019-20 to about 48 million this year, according to CDC data.
Rivers said she doesn’t think lagging vaccination rates are playing a role in the high volume of cases this year.
“The vaccine is not really supposed to protect against infection and therefore transmission. It is simply to prevent serious illness,” she said.
Instead, she says, the new flu strain — the K subclade, which accounts for most viruses analyzed by labs — appears to be the reason for this intensity.
She said this strain is just different enough from the flu viruses that people have been exposed to in the past to evade our immune defenses.
The K subclade began spreading after strains were chosen for this year’s flu vaccines, meaning the vaccines likely provide only partial protection against this disease.
“I think this virus, as we’ve seen in Australia and Japan and to some extent in the U.K., has some legs,” Osterholm said. “I think you’re going to continue to see activity in communities for at least three to four weeks of a real and substantial nature.”
CNN’s Jen Christensen contributed to this report.
