You can get vaccinated even if you have had COVID-19 – having the disease corresponds to one vaccine dose

The Finnish Institute for Health and Welfare (THL) has added detail to its recommendation on vaccinations for persons who have had COVID-19. The first dose of the vaccine can be administered to unvaccinated persons aged 18 and over as soon as two months after they have had the disease. Those aged under 18 can get a COVID-19 vaccination four to six months after having had the disease.

“If you have had COVID-19, this does not mean that you cannot be vaccinated. The immunity formed as a result of contracting the disease is preserved for at least 6 to 12 months, and it is likely that it also gives you at least partial protection against a severe disease caused by virus variants”, explains Merit Melin, Research Manager at THL.

Having had COVID-19 triggers an immune response that corresponds to one vaccine dose. Research has found that in a person who has had the disease, the response to a single dose is at least equally good as in those who have received two doses but not had the disease. 

If a vaccinated person contracts the disease caused by COVID-19, the disease strengthens the protection given by the vaccination in the same way as a booster vaccination in persons who have not had the disease.

“When a person who has had two vaccinations contracts a COVID-19 infection, this strengthens the immunity triggered by vaccines. In those who have received two vaccinations, a COVID-19 infection probably affords protection that is even better and longer lasting against the variant that caused the disease than the current vaccines”, Melin continues.

A second dose for those who have had COVID-19

In December 2021, THL recommended offering a second dose of the vaccine to those who have had the COVID-19 disease. In those who have had the disease, a second vaccine dose has the same effect as a third dose administered to persons who have not had the disease.  

A second dose is recommended for people aged 60 or over and those in at-risk groups 3 to 4 months after they received the first vaccine dose or had the disease, whichever happened the most recently. Adults aged under 60 are offered a second vaccine dose 4 to 6 months after having had the disease or received the most recent dose. A second dose may be administered earlier than this if it is necessary for travelling or other weighty reasons. 

If the person received their first vaccine dose before contracting a COVID-19 infection, the interval between the administration of the vaccine and the infection must be sufficiently long, or at least six weeks, in order for the infection to correspond to a vaccine dose. 

“When the interval between the vaccinations, or the infection and a vaccination, is longer, a better immune response is triggered. If the vaccine is administered shortly after a person has had the disease, it may also cause more severe temporary reactions to the vaccine, including fever, headaches as well as muscle and joint pains”, says Melin.

A third vaccine dose for those with severe immunodeficiency

THL recommends a third vaccine dose for persons aged 12 and over with severe immunodeficiency who have had the disease. Other people who have had the disease do not need a third dose to protect them, at least not for the time being. 

A third dose can be administered to others who have had the disease if this is necessary for travelling or some other weighty reason. In this case, a third dose can be administered on the same schedule as other third doses. 

Further information

Suitability of COVID-19 vaccines for various groups

Merit Melin
Research Manager
THL
[email protected]