Guest blog: The flu vaccine is the most effective way to avoid the flu

Seasonal flu and its complications affect people of all ages every winter. In Europe, about 50 million people get sick from them every year. The most effective way to protect yourself from the disease is the flu vaccine. How can the changing flu viruses be combated more effectively in the future and people protected from the disease?

1.    What kind of disease is influenza, who is it most serious for and how can you protect yourself from it? 

Influenza viruses cause common upper respiratory tract infections every winter, called seasonal influenza. They spread in epidemics, but their circulation was affected by various restrictions during the coronavirus pandemic. Typical symptoms of influenza are high fever, muscle pain, headache, malaise and respiratory symptoms. Influenza can be particularly dangerous for the elderly, pregnant women and babies, as well as those with a weakened immune system. Influenza can also cause other complications, such as ear infection or bronchitis. 

Influenza spreads easily between people through contact or droplets when someone coughs or sneezes. Good hand hygiene and flu vaccination are effective ways to prevent infections. It has been estimated that flu vaccinations could save European health care up to 332 million euros per year, as patient visits caused by influenza would decrease (Vaccines Europe, 2022). 

In Europe, about 50 million people get sick from influenza every year and 15,000-70,000 people die from the disease or its complications (Vaccines Europe, 2022).

2.    Flu vaccines are already in use. Why are vaccines still being researched? 

Influenza A and B viruses change constantly and cause seasonal influenza, which spreads in epidemics. Vaccine production aims to anticipate which viruses will be most common in the next season. The effectiveness of the vaccine depends on how well the prediction has been correct. Researchers are developing vaccines that better match the virus strains circulating in each epidemic season. 

The immune system of the individual also affects the effectiveness of the flu vaccine. Research is looking for effective vaccines especially for risk groups such as children under 3 years of age and the elderly. The aim of the research is also to find a universal flu vaccine that would provide long-term protection and would not need to be taken every year. Flu vaccines are also monitored during their use. For example, a high-dose flu vaccine for the elderly was studied in Finland in a large study, which had to be interrupted due to the coronavirus pandemic.

3.    What have flu vaccine studies achieved? 

The development of flu vaccines and the participation of volunteers in vaccine trials enable better protection against influenza. Vaccination programs are updated with new vaccines. Flu vaccinations have reduced the suffering and mortality caused by the disease and eased the situation of health care. However, every winter many suffer unnecessarily from influenza: for example, before the coronavirus pandemic, at most only 42% of children under 3 years of age received a free flu vaccine (THL).
In Finland, two different types of influenza vaccines have been reserved for children (from 6 months to 6 years old) who are part of the national vaccination program. Children under 2 years of age have an injectable vaccine and children aged 2–6 have a nasal spray vaccine. Both vaccines have been extensively studied in Finland as well. 

The nasal spray vaccine prevents about 5–8 cases of influenza out of ten. Sometimes the vaccine does not prevent infection, but the disease is often milder than without the vaccine. 

As a result of vaccine studies conducted in Finland in the 2000s, people now receive a quadrivalent influenza vaccine instead of a trivalent one, which means better protection. The same is sought with a plant-based influenza vaccine, the introduction of which is assessed on the basis of studies. 

4.    What would be the best possible flu vaccine in the future? 

Future flu vaccines will better match the circulating virus strains and thus provide stronger protection against the virus. In the future, vaccines can probably also be tailored to suit different age groups. The effectiveness of the vaccine can already be increased by using an adjuvant in the vaccine, which helps the body produce a better immune response. The effectiveness can also be increased by increasing the amount of active ingredient or influenza antigen in the vaccine. 

In the future, it is important to produce the flu vaccine quickly, so that the flu viruses do not have time to change. The closer to the epidemic season the vaccine is ready, the better it matches the circulating virus strains and the more effectively it prevents the disease. The production process of the vaccine can be accelerated by using, for example, mRNA vaccine technology. The mRNA vaccine does not contain antigen, but the body forms the active ingredient itself according to the instructions of the mRNA vaccine. The body’s defense system recognizes this substance as foreign and begins to produce antibodies against it. This way, the vaccine teaches the body to fight off the actual disease. 

5.    For whom is the flu vaccine especially important? 

The flu vaccine is important for people who are prone to getting a serious disease. Children get sick with influenza a lot. According to estimates, every winter about 20–30% of children get sick with influenza, and in daycare children, morbidity can be up to 50%. An effective vaccine protects young children and their loved ones. 

6.    Why participate in a vaccine study? 

Vaccines prevent diseases and improve people’s quality of life. They also play an important role in global preparedness for epidemics. High-quality vaccine research provides new vaccines and improves people’s protection against serious diseases. Research also updates national vaccination programs. By participating in a vaccine study, you can get yourself or your child a better vaccine protection and try tomorrow’s vaccines today. Studies are strictly monitored and participant safety is paramount. 

Author:

Mika Rämet 
MD, Professor of Pediatrics and Experimental Immunology