Experts urge public to get vaccinated amid flu strain subclad k

Most hospital patients in Hong Kong have little to undetectable levels of neutralizing antibodies against this season’s mutated flu strain, a situation described as concerning by researchers at the University of Hong Kong, who urged the public to get vaccinated as soon as possible.

The study, led by Kelvin To Kai-wang, chairman of the Department of Microbiology, and Ivan Hung Fan-ngai, head of the Division of Infectious Diseases at HKUMed, focused on the newly emerged H3N2 strain known as subclade K.

Serum specimens collected from public hospitals were analyzed to track viral genetics, antibody responses, and immunity levels among the local population.

Results from 277 samples taken in November revealed a stark contrast between immunity to older and newer strains.
While 52 percent of individuals had detectable antibodies against the previously dominant subclade J.2.2, with 27 percent showing relatively strong protection, only 18 percent had detectable antibodies against subclade K.

Alarmingly, just 0.7 percent reached the threshold considered strong immunity.

“Our findings suggest that the local community’s immune barrier against the subclade K is insufficient and lower than that against the previously circulating subclade J.2.2,” Hung said.

To reduce the risk of severe illness, the team urged residents to get vaccinated. They pointed to research from England showing flu vaccines can cut emergency visits and hospital admissions by up to 75 percent in children and adolescents, and by around 32 to 39 percent in adults.

The experts also advised those with flu symptoms to seek early testing and medical care, noting that antiviral drugs are most effective when taken within 48 hours of onset.

To stressed that the findings should serve as a clear warning. “With influenza A cases rising and new variants emerging, we must reinforce the message that vaccination is the most effective way to prevent infection,” he said.