The number of new coronavirus infection cases linked to visitors who returned to Finland from Russia without being tested at the border last week is growing rapidly, according to Mika Salminen, director of health security at the Institute for Health and Welfare (THL).
As of Sunday evening there were an estimated 200 new cases linked to the incident in Finland, a figure that has doubled since last Thursday.
He noted that more than half of the country's new coronavirus cases have been traced to last week's eastern border crossing.
Last Tuesday, about 800 people were allowed to enter Finland at the Vaalimaa border crossing without undergoing a coronavirus test or health checkup. Authorities made an exception to the rule about testing as traffic was heavily congested at the border crossing, as hundreds of football fans returned from watching Finland play Belgium in the European Championship finals in St. Petersburg on Monday evening.
Salminen said that most of the new cases have been detected in the capital area.
"There are cases all over Finland, but about 80 to 90 percent of them are here in the Helsinki metropolitan area, and most of them are in Helsinki," he said.
200 cases in HUS linked to football trip
On Monday, the Helsinki and Uusimaa Hospital District (HUS) announced that municipalities across the area have diagnosed a total of 202 coronavirus cases among individuals who returned from Russia last week. Nearly 500 individuals affected by the cross-border visit have been quarantined.
"The situation is extremely worrying and requires accountability. If someone got a negative result from tests taken in Russia or at the border, it does not necessarily mean there the person is not infected," HUS chief medical officer Markku Mäkijärvi said in a statement issued by the district on Monday.
"There could be many times more people who were exposed [to the virus], even thousands," Mäkijärvi said, noting that the fact the tourists arrived by bus made it particularly difficult to track down possibly-exposed individuals.
Lists of passengers aboard the buses were incomplete, with some of the travellers' information missing, including names, addresses and telephone numbers, he said.
The physician said that everyone who travelled to Russia must take a coronavirus test after a period of 72 hours have elapsed since crossing the border, and also whenever Covid symptoms appear.
According to Russian news agency Tass, the number of active Covid-19 cases across Russia — nearly 700,000 — was the highest figure recorded in the country since late February. Over the past day, the city of St. Petersburg recorded 1,335 new cases, while there were 21,650 new cases confirmed in that time period across the country.
The news agency reported on Monday that Russia's relative daily increase rate of new coronavirus cases stood at 0.4 percent.
Salminen said it remained unclear how large a role the coronavirus Delta variant had in the situation. Lab tests that confirm variants can take one or two weeks to process.
"[The Delta variant] is clearly on the rise in Russia, so the possibility is quite large," he said.
He did not rule out the possibility of local lockdown measures in affected areas, if the virus begins to spread.
"It all depends on getting new cases to stop in the first place so there are no additional ones. This has a lot to do with personal responsibility. Each case poses risks of further infections and then worsening the epidemic," he said.
"It is really important for people who visited St. Petersburg to not go to work and to be tested and wait to see the results," he urged, underscoring that people who crossed the border in buses were at particularly high risk of having contracted the virus and infecting others.
Salminen said that he did not consider the current situation to be the beginning of a major crisis, but emphasised how important it was for the football tourists to get tested.
He said the spread of infections stemming from the St. Petersburg visitors will be visible in Finland's coronavirus case statistics within one or two weeks.
Edited at 14:12 on 28 June to add information including case numbers in HUS area.