Flu vaccination in times of COVID-19 useful, necessary or unnecessary?
Influenza and COVID-19 both cause respiratory disease with a variable course of illness. This can range from few or no symptoms to a serious, life-threatening condition. Despite sharing similar preventive measures, the risk of catching the flu has not disappeared. In these circumstances, is it worth getting vaccinated against flu or not?
They are both caused by RNA viruses and transmitted through droplets and direct or indirect contact with infected objects. Several of the measures to prevent the two diseases from spreading are also identical: keeping your distance, hand hygiene, sneeze and cough etiquette and good ventilation.
Yet there are also differences. Influenza has a shorter average incubation period (= time between infection and the appearance of symptoms) and spreads more quickly than COVID-19. The reproduction number (= the number indicating the average number of people infected by someone who is themselves infected) is higher for COVID-19. The rates of serious and critical infections and mortality are also higher for COVID-19. In a community, children are significant spreaders of flu while when it comes to COVID-19, preliminary results indicate that children are mainly infected by adults.
Arguments for flu vaccination in times of COVID-19
Vaccination leads to the production of antibodies in the body which protect you on contact with the virus. A vaccine doesn't just protect you. If many people get vaccinated the virus will spread less quickly. Vaccinated people therefore also protect those who are not vaccinated and contribute to what is known as group or herd immunity.
Vaccinations approved by health authorities are safe and offer good protection. The flu vaccine only protects against flu, the COVID-19 vaccine only protects against COVID-19.
Despite sharing similar preventive measures, the risk of catching the flu has not disappeared. And as the corona measures are relaxed there is an increased risk of being exposed to the flu virus over the winter months. With the low number of flu cases last year, there is also a lack of recent natural immunity.
Available flu vaccines
Most flu vaccines are inactivated (non-living) injectable vaccines that contain antigens (surface proteins) of flu viruses, against which our bodies develop antibodies.
Influenza viruses mutate rapidly and frequently, so the antigens are constantly changing. As a result, the vaccines need to be updated annually.
Based on the virus types in circulation, the WHO makes an annual determination of the virus types for which vaccines are to be developed. A flu vaccine therefore contains components of various virus types. The vaccines contained three components up to and including 2017 but there have been four since 2018: two Influenza A components and two Influenza B components. Three tetravalent vaccines are available in Belgium for the 2021-2022 flu season.
Who should get vaccinated against flu?
A flu vaccine is recommended for people at higher risk of becoming seriously ill (high-risk individuals), people working in the health sector and people living with high-risk individuals or children under six months of age. High-risk individuals include all those 65+, those suffering from underlying chronic conditions, all pregnant women, institutionalised individuals, and children from 6 months to 18 years of age who are on long-term aspirin therapy.
Anyone who has experienced a severe form of COVID-19, which takes a toll on the body, should also get vaccinated against the flu. Furthermore, a flu vaccination also makes sense for people aged between 50 and 65, especially those who smoke, drink in excess and/or are obese.
Finally, anyone else can be vaccinated to protect themselves, to reduce the risk of transmission to high-risk individuals (= contributing to group immunity or helping to prevent absence from work).
Best time for vaccination
Belgium's Superior Health Council recommends vaccination from mid-October onwards, but vaccination at a later stage, even after a flu epidemic outbreak, can certainly still be worthwhile. The vaccine offers protection from 10 to 15 days after the injection.
Experts recommend a 14-day waiting period between a COVID-19 vaccine and a flu vaccine. The main purpose of this is to know which vaccine caused any side effects if they occur. However, the vaccines have no bearing on each other and shortening the interval has no impact on efficacy. In time, this waiting period is likely to disappear and combined vaccines may even emerge.
Don't give the flu a chance: protect your employees
This viral infection creates an annual peak in absences due to illness and may have a noticeable impact on your organisation. But just one shot can protect your employees from the flu.