Produced as quadrivalent recombinant influenza vaccine, Flublok® is considered to be the next generation of influenza immunization, and is classified as the competent seasonal influenza vaccination for the 2021/2022 season in Hong Kong. Any individual aged 18 years or above will be eligible for taking the quadrivalent vaccine, and it could yield better protection than the traditional influenza vaccines. Comparing to the standard quadrivalent inactivated influenza vaccine, it is proven to be 30% more effective in preventing flu for the population aged 50 years or above, and the hemagglutinin (HA) antigen per strain is triple to the ordinary vaccine as well. Apart from that, the new vaccine can offer 40% additional cross-protection than standard vaccine, i.e. can still offer protection to the recipients towards virus strains other than those specified in vaccine.
Seasonal influenza is a common respiratory tract infection caused by human seasonal influenza viruses. The influenza viruses could be transmitted through respiratory droplets, and could be latent for 1-4 days. At the onset of influenza, the infected individual will manifest symptoms including malaise, runny nose, headache, coughing, fever and sore throat and etc. In Hong Kong, seasonal influenza is usually prevalent in months like from January to March and from July to August. Quadrivalent influenza vaccine is eligible for individuals aged 6 months or above, and is advised to be taken for comprehensive protection against influenza.