The results of pragmatic FinFluHD influenza trial conducted in Finland have been published in a peer-reviewed “Influenza and Other Respiratory Viruses” journal. The trial evaluated the effectiveness of the high-dose flu vaccine in people over 65 years of age.

The goal of the FinFluHD trial was to find out whether a high-dose vaccine containing four influenza virus strains protects against serious circulatory and respiratory diseases that occur as sequelae of influenza better than a vaccine containing a standard dose, which is also used in the national vaccination program in Finland. The high-dose vaccine contained antigens of the same four virus strains as the standard flu vaccine, but the high-dose vaccine had four times the amount of active antigens.

FinFluHD was internationally the first large pragmatic field study of its kind on the topic. Vaccinations were administered in health centers (13) and study data were retrieved from national health registers. The study was conducted by the vaccine research team of the Finnish Institute of Health and Welfare (THL), which in 2022 became part of the special-assignment company of the state: FVR – Finnish Vaccine Research Ltd. The study was carried out in cooperation with the vaccine manufacturer Sanofi.

The use of national registers, such as the hospital care register, the infectious disease register and the population register, is an effective way to collect information on large populations, as the registers contain extensive data on the entire population. In international comparison, Finland has particularly high-quality, comprehensive and up-to-date registers.

The study was planned to extend over 2–3 flu seasons, but the COVID-19 pandemic that started in March 2020 and the restrictions that followed cut off influenza virus infections in the population almost completely. Before the study discontinuation, during the first flu season in the fall of 2019, 33,093 volunteers were vaccinated as planned; half of them received the high-dose flu vaccine and the other half received the standard-dose vaccine.

The findings support the use of the high-dose flu vaccine in people over 65: those who received it had 5.5 percent fewer circulatory and respiratory diseases that led to hospitalization than those who received the standard dose used in the national vaccination program. In particular, hospitalizations due to coronary artery disease occurred about a third less in those who received the high-dose vaccine than in those who received the standard vaccine.

“The results should be interpreted with caution and additional studies are needed, because the FinFluHD study had to be discontinued due to the COVID-19 pandemic. However, the successful execution of the study during the first influenza season is an excellent demonstration of the Finnish register study expertise and our ability to carry out large-scale studies. The results also encourage further studies on more effective influenza protection for aging people,” states Arto Palmu, FVR’s Chief Research and Medical Officer.

Link to the article in Influenza and Other Respiratory Viruses >>