Officials are urging doctors to vaccinate their patients and provide flu antivirals after deaths among children reached record highs and as a concerning mutation of the virus circulates in the US.
“Influenza activity is increasing in the US. The time to get vaccinated for this season is now,” Timothy Uyeki, the chief medical officer of the influenza division at the US Centers for Disease Control and Prevention (CDC), said in a call with clinicians last week.
The message comes amid diminishing access to and flourishing rumors about vaccines under Robert F Kennedy Jr, the secretary of the Department of Health and Human Services, who has made false claims about the ineffectiveness of flu vaccines and overseen limitations on routine vaccines.
After a year of dramatic cuts to staff and programs at health agencies, CDC officials highlighted the need to continue monitoring variants such as the H3N2 virus subclade K – currently the top strain in the US – as flu season unfolds.
“It’s hard to say what will happen throughout the season, and that’s why we need surveillance to really track this,” Uyeki said.
A child died of the flu in the week ending 22 November, marking the first known pediatric death this season, the CDC reported earlier this month.
The CDC also reported another child death from flu during last year’s season, bringing the total to 288 – the deadliest pediatric flu season on record outside of a pandemic. Last year, there were an estimated 610,000 to 1.3 million hospitalizations from influenza in the US.
“Last season, by all indicators, was a high severity season and one of the highest we have experienced in the US,” Uyeki said.
Officials at the CDC on last week’s call highlighted changes in vaccine policy – including a new recommendation against thimerosal, a preservative also known as thiomersal, previously used in a small percentage of flu vaccines. The CDC’s vaccine advisers voted to recommend only flu vaccines without the preservative in a June meeting.
The top regulators of vaccines and drugs at the US Food and Drug Administration (FDA) also recently announced changes to how flu vaccines will be approved, which may include extensive trials each year for children and pregnant people that would put annual vaccination out of reach.
Children, pregnant people, immune-compromised people, and the elderly are among those at highest risk of illness and death. Vaccines protect against severe complications like pneumonia, cardiac complications, neurological issues, and encephalopathy, or brain dysfunction.
There were 109 cases of encephalopathy among children last year, with 74% needing intensive care and 54% needing mechanical ventilators. Most (55%) of the children with encephalopathy had no underlying conditions – except for not being vaccinated. Only 16% of the children who were eligible had gotten vaccinated. Nearly one in five (19%) of the children with encephalopathy died.
“The majority of these are preventable, and this is really, really tragic,” said Uyeki.
“This is the highest number of deaths for a seasonal influenza epidemic since we’ve been keeping track, and clearly highlights the fact that we need to do a much better job of preventing influenza and preventing influenza-associated death in children in the United States.”
Last year, the vaccine was 63% to 78% effective at preventing hospitalization among children and 41% to 55% effective against hospitalization among adults.
In August, the CDC identified the new variant (H3N2 virus subclade K), which mutated from the version of H3N2 included in the vaccine – raising concerns that the flu vaccine might be less effective this season.
As the flu season in the US is only beginning now, there is too little data so far to calculate how effective the vaccine is against it.
“It’s too early to know what impact exactly this new subclade will have on the influenza vaccine effectiveness for this season,” said Lisa Grohskopf, also a medical officer in the CDC’s influenza division.
“It takes a little while before accumulating enough activity and specimens to be able to calculate [vaccine effectiveness].”
Based on early numbers from the United Kingdom, which had an early start to the flu season, vaccine effectiveness is about 70 to 75% for children and 30 to 40% for adults – similar to prior vaccine efficacy.
The evidence indicates that “influenza vaccination remains an effective tool in preventing influenza-associated hospitalizations for the season”, Grohskopf said.
The flu vaccine is recommended for everyone six months and up, she said.
Providers have been recommending FluMist more to patients who are eligible. It’s not a shot, which may assuage vaccine hesitancy. And it may now be given at home by a caregiver or the patient after a major change from the FDA in September 2024.
Antivirals are also a safe and effective way to treat and prevent severe illness, including in pregnancy, and they work best the sooner they can be started.
In recent years, flu antiviral prescriptions have dropped, Uyeki said. Only 35% of children at high risk are prescribed antivirals, and only 32% of children who visited emergency departments because of flu were prescribed antivirals.
