Courtesy / Carol E. Davis, U.S. Army Corps of Engineers
After peaking in mid-February, flu rates are on the decline across the state of Texas following a relatively mild season compared to last year, according to the Department of State Health Services.
While rates have continued to decrease, Bexar remains one of 13 counties in Texas with culture-confirmed flu A and B, and the San Antonio Metropolitan Health District reported the first local pediatric death during the last week of March.
“It’s not uncommon to find one to two flu-related deaths locally [per year], but even one is too many, especially when it’s preventable,” said Dr. Anita Kurian, assistant director of the Communicable Disease Division at Metro Health.
Kurian told the Rivard Report that this year’s flu vaccine is 47 percent effective, compared with 36 percent last year; and while it’s difficult to say whether that the mild season an be attributed to vaccinations alone, it indicates an improvement in protection against the particular virus strains in this year’s vaccine, which includes two different strains of both flu A and B.
The National Institutes of Health (NIH) is currently on a quest to develop a vaccine that could provide immunity to nearly all strains of the flu virus. Researchers at the NIH Clinical Center in Bethesda, Maryland, began testing the first “universal” flu vaccine aimed at providing long-term immunity to all types of flu on April 3.
The first clinical trial will evaluate the vaccine’s ability to trigger an immune response in the body, along with its safety and tolerability based on age and previous exposure to different influenza variants.
According to the NIH, study participants will be asked to log their temperature and any symptoms for one week after each injection. They also will be asked to provide blood samples at various times.
Investigators will test the samples to characterize and measure levels of anti-influenza antibodies, which could indicate immunity against influenza, then monitor the participants over the next 12 to 15 months to evaluate how their bodies respond to the vaccine.
The NIH expects the clinical trial to complete enrollment by the end of 2019 and hopes to begin reporting results in early 2020.
Dr. Jason Bowling, infectious disease specialist at UT Health San Antonio, said the issue with the flu virus and the ability to successfully vaccinate against it is that the virus is constantly going through minor changes in the surface protein hemagglutinin, which binds the virus to human cells.
“The best way to look at hemagglutinin is to view it like a flower with a stem and a head,” Bowling said. “The head region sticks out above the virus’s body, while the stem is mostly hidden under the head and within the body of the virus. Current flu vaccines are designed to treat the head region, causing our immune systems to detect and make antibodies against the head of the virus.”
But the problem with that approach, Bowling said, is that the head frequently mutates, which prevents the immune system from detecting the hemagglutinin and knowing it’s time to take action. The concept behind the universal flu vaccine is to treat what is found in the stem alone, which doesn’t go through constant change.
While the NIH hopes the vaccine will provide long-lasting protection against many types of flu, it will not eliminate it entirely because it will only target type A strains, those that circulate seasonally and cause epidemics. To eliminate the influenza A strains, nearly everyone worldwide would need to be vaccinated.
There are also influenza type B, C, and D infections, all of which do not typically cause pandemics.
The Centers for Disease Control and Prevention estimates 37 percent of adults received flu vaccinations during the 2017-18 flu season, 6.2 percentage points lower than the 2016-17 season
“The good news is that there is more funding now than there was in the past supporting vaccine development, probably because this last flu season more people had died of the flu in more than 50 years. There was recognition that we are not doing as well as we could protecting people from the flu and we need a better vaccine.”