Coronavirus vaccine protects elderly, risk group better after 2nd dose

A second dose of a coronavirus vaccine is essential to give the elderly and those in the medical risk group sufficient protection against coronavirus disease, according to a study by the Finnish Institute for Health and Welfare (THL).

The study showed that the protection provided by a single dose is significant, but it does not always prevent infection, and in some cases, it will not prevent a case of coronavirus disease that requires hospital care, said the THL in a press release on Friday.

The study conducted using medical and demographic register data from Finland examined the protective effect of the first and second doses of a vaccine against coronavirus infections and cases of coronavirus disease that require hospitalisation.

The results of the study, however, are preliminary, and they have not yet been subjected to scientific peer-review.

For the elderly, the protective effect of mRNA vaccines against coronavirus infection was on average 45 percent, i.e. about 45 out of 100 coronavirus infections were prevented by the first injection.

The effectiveness of the first dose was 63 percent against coronavirus disease requiring hospital care. For those in the risk group, the results were 40 percent against infection and 82 percent against hospitalisation. The protective effects were calculated at the earliest three weeks after the first dose.

“After the first dose of the vaccine it is still possible to be infected and get ill. Coronavirus vaccines provide better protection against severe disease than against mild infections in the same way that seasonal flu shots do”, said Eero Poukka, Medical Specialist at THL.

Among the elderly, the protective effect of mRNA vaccines against infection increased to 75 percent after the second dose and to 93 percent against hospitalisation. In the risk group, the corresponding figures were 77 and 90 percent.

“These figures clearly indicate that a second dose of the coronavirus vaccine is worth taking. A second dose increases the protective effect to excellent levels both among the elderly and those in the risk group”, Poukka said.

The research included information on nearly 1.7 million recipients of the vaccine was conducted between 27 December 2020 and 24 May 2021 using medical and demographic register data.

More than 900,000 elderly persons and 775,000 persons at risk for severe coronavirus disease were followed up for their coronavirus vaccinations, infections, and related hospitalisations.