A novel form of influenza – referred to by some as “superflu” – was cause for concern as it spread throughout Florida over the holidays.
But St. Lucie County has, so far, avoided major outbreaks of this novel flu – Influenza A H3N2, subclade K – despite it becoming the most prominent flu strain in the state, according to the Florida Department of Health.
FDOH noted in their flu surveillance reports St. Lucie – like many other Florida counties – observed “increasing” trends of flu infection throughout December.
The FDOH office representing St. Lucie and Okeechobee counties did not give comment on the new flu variant’s presence in St. Lucie by press time. In addition, FDOH does not report on individual flu cases except in circumstances including widespread infections and “flu-associated pediatric deaths.”
Amid increasing flu rates, increased vaccine hesitancy that has trickled into state and federal policy may leave St. Lucie vulnerable to the risk of infectious respiratory diseases six years after the COVID-19 lockdowns.
That can translate to further infection between the county’s most vulnerable populations: school-age children and older people.
Around 89 percent of St. Lucie kindergartners were fully vaccinated against diseases of all varieties compared to 94 percent before the COVID lockdowns, according to a Dec. 31 Washington Post investigation using county-level data from across the U.S.
These findings, along with the spread of the novel flu variant, remained topical among the Cleveland Clinic Florida Research and Innovation Center (FRIC) in southwest Port St. Lucie. Dr. Ted Ross, their director of vaccine research, shared insights on research and epidemiology of subclade K in a Jan. 10 email.
“The main issue is the reduced immunity people have to this clade as well as (how approximately) 50 percent of people in the area did not receive the flu shot,” Ross wrote. The novel subclade emerged from an existing flu strain that “acquired seven new mutations over the summer.”
“H3N2 is a well-established human seasonal flu virus that has circulated in people since 1968,” Ross wrote. “It was one of the main viruses that circulated during last year’s flu season in the northern hemisphere, alongside H1N1 and influenza B.”
The subclade K flu variant differs from others via “small genetic changes to the virus’ surface proteins, including hemagglutinin which vaccines target,” Ross said. Hemagglutinin, he added, is the “‘H’ in influenza strain names like H3N2 or H5N1.”
“While the current influenza vaccine does not contain a clade K strain,” Ross wrote, “the flu shot still reduces illness, hospitalization and severe disease caused by (it).” He recommended good personal hygiene, avoiding crowds, and masks over one’s mouth and nose to prevent infection.
Other medical professionals echo this assessment, such as Dr. David J. Weber, president of the Society for Healthcare Epidemiology of America (SHEA). He also served as medical director at University of North Carolina Hospitals in over 40 years of general practice in children and adults.
“We’ve seen increasing vaccine hesitancy on the part of the public and decreasing vaccine recommendations on the part of the federal government, as well as states; obviously, Florida, as an example,” Weber said in a Jan. 6 interview.
A growing body of data exists to counter even the novel “drifts” over the summer that led to subclade K, Weber said. He added Centers for Disease Control statistics for the 2023-24 flu season – when H3N2 was the most prevalent strain in the U.S. – show vaccines “prevented 9.8 million flu-related illnesses; 4.8 million medical visits; 120,000 hospitalizations; and 7,900 deaths.”
“There’s no question that flu vaccines are safe and effective,” Weber added. “The benefits outweigh the deficits.”
Vaccines, since their development in the 1700s, use a non-replicating form of a pathogen to elicit the needed immune response and prevent “higher risk of severe outcomes,” Weber said. “In all vaccines, you’re presenting with an antigen: something that we make an antibody response to.”
The relationship between immune response continues to follow trends in age, with people being most vulnerable in their youth and older years.
Personal immunity follows “what we call a ‘J-shaped curve’,” Weber said. That curve outlines “much higher rates in the very young under two; dropping rates until about age 30; and increasing mortality as people age. That’s not to mean that at 40 or 50, you’re not healthy; you just have less physiological reserve.”