The influenza vaccine has always been quadrivalent, but in recent years, a trivalent vaccine has emerged. What's the reason? We asked Dr. Li Xuan to explain.

"Why the change to trivalent?"

According to the World Health Organization, the Yamagata lineage B virus (one of the monovalent) is no longer circulating in the human population. While the WHO still recommends four influenza vaccines, it has changed its recommendation to "trivalent provides adequate protection."

In light of this, the Hong Kong Center for Health Protection will also change its recommendation from "quadrivalent" to "trivalent or quadrivalent" starting in 2024/25. Citizens can choose to receive either influenza vaccine based on their needs. *

"Is quadrivalent effective?"

Generally speaking, a higher vaccine valence indicates wider coverage. However, since one of the viruses is considered "extinct" by WHO standards, even if antibodies are injected into the body, they are virtually ineffective and will not increase the risk of illness. However, depending on the formulation of each vaccine brand, the target population varies, so quadrivalent influenza vaccines are still available.

The government provides free influenza vaccinations to eligible individuals each year. Eligible individuals* and those who have successfully registered for eHealth^ can receive government-subsidized vaccinations. For more details on the subsidy, please visit the following link:
https://humanhealth.com.hk/zh-hant/Gov-funded-Programme/details/vssv-flu-vaccination

^New subsidy conditions for the 2025-26 fiscal year. For more details on the Vaccine Subsidy Scheme, please refer to the following link: https://humanhealth.com.hk/zh-hant/Gov-funded-Programme/details/vssv-flu-vaccination

Whether receiving the trivalent or quadrivalent vaccine, getting the latest seasonal influenza vaccine as early as possible each year is the most important preventive measure. Both vaccines effectively reduce the risk of influenza infection and serious complications. For more information on various flu vaccines, please visit the following link:

https://mall.humanhealth.com.hk/collections/flu-vaccine

If you have any further questions about flu vaccines, please feel free to leave a message or send us a message via WhatsApp.