Explosion of Western Pennsylvania flu cases blamed on vaccine 'mismatch'
The nearly 7,000 confirmed cases of the flu this season in Western Pennsylvania help validate new information from state and federal health agencies: More people are getting sick from influenza, including nearly half of those who got a flu shot.
“There seems to be a mismatch in the vaccine and the strains we're seeing,” said Dr. Marc Itskowitz, an internal medicine specialist at Allegheny General Hospital in the North Side.
The Centers for Disease Control and Prevention on Thursday reported the flu vaccine is 56 percent effective — which is considered moderately successful. The agency amended an earlier estimate that the vaccine appeared to be 62 percent effective.
Scientists consider a 60 percent to 70 percent effectiveness rate for a flu vaccine to be good, as flu viruses mutate quickly and multiple strains can circulate at once.
The new CDC estimate is based on information from almost 2,700 children and adults enrolled at the U.S. Influenza Vaccine Effectiveness Network's five study sites, one of which is the University of Pittsburgh Schools of the Health Sciences in partnership with UPMC.
The new CDC estimate shows that the vaccine is 27 percent effective in adults 65 years and older nationwide, but only 9 percent effective in preventing illness from Influenza A — the most common and deadliest strain — in that age group.
Those estimates are based on 300 people in the study, which is too small a sample to draw solid conclusions, said Dr. David Nace, chief medical officer for UPMC Senior Communities.
“I think the vaccine overall this year was pretty good,” Nace said. “We saw a lot of flu. But I think this would have been a heck of a lot worse without it.”
More than 34,000 people across Pennsylvania have tested positive for the flu this season, according to the state health department. That is nearly 12,000 more than the last two years combined.
“This was the earliest and busiest flu season in the last 10 years,” Itskowitz said. “Last year was the lowest and shortest peak ever.”
Cases in Allegheny County jumped from 412 last year to 2,703 and across the region from 713 to 6,927, state records show.
“And that's really just the tip of the iceberg,” said Guillermo Cole, spokesman for the Allegheny County Health Department.
“We realize there are more than the confirmed cases. A lot of people with the flu don't even go to the doctor, and not all those who do get a test.”
Flu bugs started appearing here in October and peaked in late December and early January, Cole said. Flu-like illnesses account for about 3 percent of emergency room visits at six Pittsburgh hospitals, down from a peak of 7 percent weeks ago, Cole said. Flu accounts for 2 percent of hospital visits all year.
Nearly all the flu cases in Allegheny County this season involved Influenza A, Cole said, though hospitals now are reporting a spike of Influenza B.
About 24,000 people nationwide die from the flu each year, the CDC reports. Through last week, 154 people across Pennsylvania died from flu-related causes, a season record.
Allegheny County records show flu-related illness killed 14 residents this season. They ranged in age from 53 to 98, Cole said.
Starting next year for the first time, manufacturers will produce a flu vaccine that contains four strains — two each for Influenza A and Influenza B — instead of three.
Researchers at Pitt are working on more effective flu vaccines, said Dr. Ronald Montelaro, co-director of the school's Center for Vaccine Research. Those vaccines would focus on parts of the flu virus that do not change rather than proteins which often morph and dupe the immune system into attacking the wrong part of the virus, he said.
“This virus continues to evolve. It's a moving target,” said Montelaro, who predicted more effective vaccines would be available within a decade.
But people shouldn't skip the ones available now, he said, even if it works for just over half of those who take it.
Nearly 135 million doses of this season's flu vaccine had been distributed through Feb. 15, CDC records show.
Montelaro noted that many who got the flu after being vaccinated experienced milder symptoms and a shorter illness.
“And that's not a bad outcome for people who the vaccine didn't protect completely,” he said.
Jason Cato is a staff writer for Trib Total Media. He can be reached at 412-320-7936 or firstname.lastname@example.org.