The current flu vaccine continues to demonstrate efficacy in protecting against severe infections though a genetically mutated strain of the influenza A (H3N2) virus is disseminating within the city, according to the respiratory expert David Hui Shu-cheong from the Chinese University of Hong Kong.
Speaking on a television program on Sunday, Hui noted that the H3N2 strain has acquired seven new mutations over the summer, boosting its transmissibility.
He noted that for every 100 individuals infected with the mutated strain, an additional 140 may subsequently become infected, in contrast to 120 infections prior to the mutation.
Despite the antigenic drift reducing the jab’s ability to prevent infection, Hui emphasized that the current flu vaccine still provides protection against serious complications and hospitalizations.
He cited a study from the UK health authorities that the vaccine offers a protection rate of 70 to 75 percent for children aged two to 17 in preventing hospitalization, and approximately 30 to 40 percent for adults.
He said the influenza typically declines six to eight weeks after reaching its peak; however, due to the cooler weather and high transmissibility of the mutated strain, the flu season might be prolonged, potentially overlapping with the winter flu period spanning from January to March.
He added that significant mutations of flu virus strains are uncommon, with the last major occurrence noted during the 2014/15 season.
It is currently difficult to predict whether the virus will mutate further, Hui said, adding that the World Health Organization will collect data from relevant laboratories around the world to continue monitoring the situation.
