Flu cases rose on Long Island last week, but end of sick season is near

Flu season isn’t over yet.

Cases across the state increased 17% last week and ticked up on Long Island in recent weeks after steadily declining through the end of January, according to the state Health Department.

Nassau County saw 880 lab-confirmed cases for the week ending March 14 — the highest since mid-January, data shows. About one month ago, 892 cases were reported from Suffolk County.

Those numbers are still far lower than they were during the peak of the rough flu season, on Dec. 20, when there were more than 15,000 cases on Long Island and 75,654 across the state.

“It's not surprising and it signals sort of the last hurrah of flu before it goes away,” said Dr. Bruce Farber, chief of public health and epidemiology at Northwell Health. "I would guess that within two to three weeks, the influenza season will be almost gone."

Farber said 85% of all cases of influenza that occurred so far this month were influenza B, and 11% were influenza A.

“That's a 100% dramatic decrease from what it would have been in December or January or even February,” he said, when the vast majority of cases were influenza A. “And influenza B tends to occur right at the end of the influenza season and the end of the respiratory virus season.”

Farber said flu B cases tend to be much less severe than flu A cases.

“It's a totally different virus, and the epidemiology of it is not well understood,” he said.

Even if a person had flu A earlier in the season, it does not protect them from getting flu B later.

Dr. Sharon Nachman, chief of pediatric infectious diseases at Stony Brook Children’s Hospital, said lower flu vaccination rates and poor matches between the vaccine composition and circulating strains are a big part of the problem.

Scientists have to decide months ahead of the flu season which strains to include in the vaccine. Because the virus is constantly changing, it doesn’t always match.

“At any given point, there are multiple circulating stereotypes for (strains) of flu,” Nachman said. “The flu vaccine contains 3 flu A's and one flu B ... but there may be 10 [strains] circulating — the math is not in our favor.”

This season, the subclade K variant of the H3N2 virus emerged as a dominant factor after the vaccine was formulated. As a result, the vaccine was only about 40% effective in preventing kids with the flu from becoming sick enough to go to the doctor’s office or a hospital, according to interim estimates from the Centers for Disease Control and Prevention. 

For people over the age of 18, the vaccine’s effectiveness was between “22% and 34% against influenza outpatient visits and 30% against influenza-associated hospitalization,” the CDC report stated.

At least 26 million illnesses, 340,000 hospitalizations and 21,000 deaths were caused by influenza between Oct. 1 and Feb. 28, the agency estimated.

“Each year we don’t do a good job matching, we get a huge volume of people who are sick,” Nachman said. “The following year, some people thought, 'If it didn’t work last year, why should I bother this year?’ So you get into a cycle where less people vaccinate.”

She said there needs to be a better flu vaccine created with new technology, but the rise in vaccine hesitancy and the federal government’s roughly $500 million pullback on mRNA vaccine development may be discouraging to many pharmaceutical companies.

By Lisa L. Colangelo

lisa.colangelo@newsday.com@lisalcolangelo

Lisa joined Newsday as a staff writer in 2019. She previously worked at amNewYork, the New York Daily News and the Asbury Park Press covering politics, government and general assignment.