The Finnish Institute for Health and Welfare (THL) has recommended that the Moderna coronavirus vaccine not be administered to men aged 30 and under.
Speaking at the weekly coronavirus briefing on Thursday morning, THL Director of Health Security Mika Salminen said that younger men had a slightly higher risk of developing myocarditis — an inflammation of the heart muscle — from the vaccine.
The inflammation can reduce the heart's ability to pump blood and can also lead to rapid or abnormal heart rhythms.
"Most cases of myocarditis are mild and pass quickly, requiring a couple of days of patient monitoring," Salminen said, adding that the greatest risk appears to be for young men receiving their second dose of the vaccine.
THL's recommendation follows announcements by authorities in both Sweden and Denmark on Wednesday that they will suspend use of the Moderna vaccine for younger age groups due to reports of possible side effects.
Salminen said that fewer side effects have been reported in Finland than in other Nordic countries, citing Norway as one example.
"But for this reason, in accordance with the precautionary principle, THL's instructions are that the Moderna vaccine should not be given to men and boys under the age of 30 for the time being, but that the Pfizer vaccine should be used instead," he told the press briefing.
If men under the age of 30 have already received the Moderna vaccine as their first dose, they can be given the Pfizer vaccine as their second.
"It is important that the second vaccine is still taken," Salminen added.
Finland has received about 1.35 million doses of the Moderna vaccine, of which an estimated one million have so far been administered.
Finland's vaccination rollout slowing
Also speaking at Thursday morning's briefing, THL specialist Mia Kontio said that Finland's rate of vaccination has slowed in recent weeks.
About 20,000 people have received their first doses over the past week, while approximately 120,000 have got their second jab, Kontio said. These figures are lower than usual, and Finland's vaccination rate has now fallen below the average of other EU member states.
Kontio said this was due to Finland's relatively long interval between first and second doses, which was once as long as 12 weeks, but has been "closing all the time".
She added that, according to THL's latest figures, there are about 775,000 unvaccinated people in Finland aged 12 and over.
"Vaccination coverage has not yet reached such a large number of people, and widespread transmission of infections is still possible," she said.
However, the government's target of 80 percent vaccination of those aged 12 and over can still be achieved by the end of October, according to THL's estimates.
Infections rising
As the vaccination rate slows, the number of lab-confirmed coronavirus cases being reported in Finland is on the increase, Pasi Pohjola of the Ministry of Social Affairs and Health told the press briefing.
In total, 3,826 cases were reported last week, which is about 800 more infections than were reported the previous week.
Finland's incidence rate currently stands at 123 per 100,000 inhabitants over the previous 14 days, and the percent positive — the percentage of coronavirus tests performed that are actually positive — has risen to 4.9 percent from 3.5 percent last week.
"In particular, unvaccinated people who have symptoms should apply for tests," Pohjola said.
He added that while the majority of cases were detected among younger age groups during the summer, infections are now more widely spread across different age groups.
Most people become infected at home or via someone in their close circle, but social events such as meetings and parties are the second most common source of infection, Pohjola said. These sources are also much more difficult to trace, he added.
"Unvaccinated people are at significant risk of getting infected through these [situations]," he said.
Three out of four Covid patients are unvaccinated
As infections increase, so too are the number of people being treated in hospital for the virus.
By the end of last week, there were a total of 105 patients being treated in hospital for the virus, THL said, of whom 33 were in intensive care units. A week earlier, the corresponding figures were 56 patients in hospital, with 25 of them in intensive care.
THL's figures revealed that the risk of hospitalisation is highest among unvaccinated people aged between 50 and 79 years of age, which is 18 times higher than for people of the same age who have received both doses of the vaccine.
The agency added that of the people hospitalised during the month September, 74 percent were unvaccinated.