CDC: Flu vaccine worked well in short-lived season

Formulation was good match against strains that spread in fall and winter, officials say.

Early estimates suggest the flu vaccine performed well in a winter flu season that has already dissipated in Georgia and most of the rest of the country.

The vaccines were more than 40% effective in preventing adults from getting sick enough from the flu that they had to go to a doctor’s office, clinic or hospital, health officials said during a Centers for Disease Control and Prevention vaccines meeting Wednesday. Officials generally are pleased if a flu vaccine is 40% to 60% effective.

One reason is the vaccine was a good match against the strains that spread over the fall and winter, officials say.

Initially, it looked like it might be a bad flu season. The virus took off in October as COVID-19 and another respiratory virus, RSV, roiled emergency departments. But the flu also apparently made a very early exit, with the virus declining since the end of November. Flu activity has remained low in Georgia.

One expert at the CDC meeting was underwhelmed by the estimates on the flu vaccine effectiveness and said it points out the need for better flu vaccines. “It is still disappointing” that the vaccine was a good match and yet effectiveness was still modest, said Dr. Sarah Long of Drexel University.

Annual flu vaccines are recommended for everyone 6 months and older in the U.S. About half of the eligible kids and just under half of adults got flu shots in the last several months, according to CDC data. Vaccination rates were up compared with 2021-22 but below what they were before the COVID-19 pandemic hit in 2020, said the CDC’S Brendan Flannery.

The dominant flu strain was the kind typically associated with higher rates of hospitalizations and deaths, particularly among older people.

Since Oct. 8 when the flu season began, 46 people, including one child, have died from the flu in Georgia. Last year at this time, there were 17 flu-related deaths in Georgia over the same period.

In some years, the vaccines were virtually ineffective against the dominant strain in people 65 and older. But this season’s vaccine has done unusually well, with the best results seen in at least 10 years, said Flannery, who is responsible for the CDC’S flu vaccine effectiveness data.

Only a few pockets of high flu activity have persisted this month, including in New Mexico and New York City.

It’s not clear exactly why the wave crested so early, but flu seasons have been unusually mild or otherwise strange since the COVID-19 pandemic hit in early 2020, Flannery said. CDC officials also caution that flu season might not really be over: Late winter or spring second surges have occurred in the past.

Among the findings:

The vaccine was 44% effective in preventing adult lab-confirmed flu visits to urgent care clinics and hospital emergency rooms, and 39% effective for seniors age 65 and older.

It was 43% effective against flu-related hospitalizations of all adults, and 35% against flu hospitalizations of seniors.

In kids, the vaccine was 68% effective in preventing illnesses severe enough to require hospitalization, and 42% effective for pediatric visits to the emergency department.