University of Florida researchers found that most people brought to a Florida hospital during the 2014-2015 flu season had a strain of the flu that was not found in the flu shot that year. Their findings suggest a need for regional monitoring to develop a better flu vaccine each year.
This is the second year the researchers completed genetic analysis of the hospital’s most common strain of influenza, and the second year that strain was not part of the flu vaccine. Their findings were published Wednesday, December 16 in the journal Emerging Infectious Diseases.
During the 2013-14 flu season, most patients at UF Health Shands Hospital were infected with an H1N1 form of the flu. That particular mutation most affected young people, settling deep within their lungs. During the 2014-15 flu season, the variant was more traditional, a variation of the H3N2 virus.
“If you’re a vaccine manufacturer, you have to come up with a vaccine that will protect you against viruses that are circulating,” said Dr. John Lednicky, primary author of the paper and an associate professor in the UF College of Public Health and Health Professions’ department of environmental and global health. “At a large university like the University of Florida, which has lots of visitors from around the world and lots of people in one spot, there’s always a good possibility that many variants of the influenza virus are in circulation at any one time.”
The researchers’ findings show why last year’s flu vaccine may not have been as effective as previous years: The vaccine did not cover the variation the researchers saw at UF. Each year, the World Health Organization determines up to four flu variants to be included in the vaccine.
“But the virus mutates very easily, and the problem is that we don’t really look that carefully at many communities,” said Dr. J. Glenn Morris, a professor of medicine, director of the University of Florida Emerging Pathogens Institute and senior author of the paper. “What this says to us is that we tend to think of the flu as this monolithic virus, but what our data show is that there are striking differences between strains of the virus.”
The researchers hope annual study of the virus can better inform manufacturers about variants of the virus that should be included in the vaccine. Flu vaccine manufacturers are also researching a universal flu vaccine that affects the part of the virus that doesn’t change as much, Dr. Morris said.
In the meantime, he and Dr. Lednicky hope to establish a regional influenza virus center to continue monitoring the disease.
“You can imagine why Florida is important. We have a lot of tourists, and we’re beginning to see influenza virus all year round here,” Dr. Lednicky said. “Variants in the flu virus tend to go unrecognized unless someone is performing surveillance and doing these kinds of genetic tests.”