In our guest blog at rokotustieto.fi, Mika Rämet, Director of the Vaccine Research Centre, explains why being vaccinated is particularly important during the coronavirus pandemic.
A few years ago, I thought I was too busy for the influenza vaccination offered by my employer. I ended up with an infection and high fever that lasted for almost a week. Since then, I have always had the motivation (and time) to have my annual vaccination.
During the pandemic, we must also remember to get vaccinated against other diseases that can be prevented with vaccination. An influenza vaccination is particularly important. However, a regrettably large number of people fail to have their annual influenza vaccinations.
An influenza vaccination is particularly important for the elderly, pregnant women and children under school age
An influenza vaccination protects against the flu, of course, but can it also affect the risk of being infected with the coronavirus?
The immune response to viral infections is largely similar for different viruses. The purpose of the defence reaction is to render cells into a state that prevents the virus from dividing until a more specific acquired response has been triggered. This seems to imply that a respiratory tract infection, such as the flu, would protect the infected person from a simultaneous infection, such as COVID-19.
At least the presence of the respiratory syncytial (RS) virus in the respiratory tract appears to reduce the likelihood of the presence of rhinoviruses. So, could having the influenza be beneficial if it reduces the likelihood of being infected with the coronavirus?
In practice, it is actually the opposite. According to the dissertation of Sinikka Karppinen, MD, the coexistence of RS and rhinoviruses prolongs and intensifies the disease in children. It can therefore be assumed that if influenza and COVID-19 are had simultaneously they would cause an infection that is more severe than they would cause separately.
It’s even more important to remember that influenza alone is a highly dangerous disease. It causes hundreds of deaths every year, especially among people aged over 75. The elderly are therefore at particular risk of being infected with both the coronavirus and influenza.
Influenza is also particularly dangerous for pregnant women and small children. It’s also good to know that vaccinations protect not only the mother, but also the baby during their first months of life.
Pneumococcal vaccine also reduces respiratory tract infections caused by viruses
In addition to being vaccinated against influenza, it’s advisable for elderly people in particular to get a vaccination against pneumonia caused by pneumococcus. The benefit may be broader than just protection against pneumococcus. According to Karppinen’s dissertation, pneumococcal vaccination reduces not only ear infections caused by pneumococcus, but also viral respiratory tract infections. This supports the idea of the synergetic role of bacteria and viruses in causing respiratory tract infections, at least in children.
Is the protective effect of the vaccination simply attributable to the fact that the mucous membranes of the respiratory tract are more susceptible to viruses when they have been damaged by bacteria? Or could another mechanism be in play?
Trained immunity provides broad protection against infections
It’s possible that being vaccinated also protects against infections other than the one at which the vaccine is targeted. This phenomenon is known as trained immunity, and it’s best known with regard to the protective effect of the tuberculosis vaccine (BCG) against Candida albicans fungal infections. In recent years, it has become clear that such an enhanced immune response lasting for several months is based on the enhanced functioning of white blood cells. This phenomenon is currently subject to very active research, and is also connected to the COVID-19 pandemic. For example, there has been research into whether the BCG vaccine reduces the risk of severe COVID-19 infection.
It’s therefore possible that if you get vaccinated against influenza and pneumococcus in the autumn, these vaccinations will also teach your immune system to respond more effectively to other pathogens.
At the very least, an influenza vaccination provides protection against the influenza, and a pneumococcal vaccination is effective against pneumococcus.
This year, I will again make sure that I have time for my influenza vaccination offered by my employer.
Professor of Paediatrics and Experimental Immunology