The number of influenza cases is likely to increase each year during its peak season. With the relaxation of social distancing measures and entry quarantine policies in various countries, the risk of influenza transmission may also increase as people and tourists no longer mandatory to wear masks in Hong Kong. In Hong Kong, local seasonal influenza activity has been low for the past three years due to past pandemic measures. The general population may be less immune to influenza than before. Given that severe cases do occur in previously healthy persons, all members of the public aged 6 months or above, except those with known contraindications, should receive seasonal influenza vaccination for personal protection. Members of the public can consult their family doctors to receive seasonal influenza vaccination for personal protection.

The circulating seasonal influenza strains may change from time to time, the seasonal influenza vaccine composition is updated every year by the circulating strains to enhance protection. According to the World Health Organization, when the vaccine strains closely match the circulating influenza viruses, the efficacy of inactivated influenza vaccine (IIV) in individuals younger than 65 years of age typically range from 70% to 90%. Therefore, it is necessary to get vaccinated against influenza every year.

Inactivated Influenza Vaccine (abbreviated: IIV) injection contain the following strains:

• A/Victoria/4897/2022 (H1N1)pdm09-like virus
• A/Darwin/9/2021 (H3N2)-like virus
• B/Austria/1359417/2021 (B/Victoria lineage)-like virus
• B/Phuket/3073/2013 (B/Yamagata lineage)-like virus