The overall impact of how hard the novel coronavirus epidemic may hit Finland can be estimated with the help of mathematical models, according to Turku University epidemiology statistics professor Kari Auranen.
The academic said the duration of the epidemic’s first wave can last at least three months, adding that the length of the viral spread can be calculated using two factors.
The first factor is the so-called R0-value - the average number of people an infected individual passes the disease to. The second factor is how quickly the infection is passed from one person to another.
In the ongoing coronavirus epidemic, Auranen explained, the R0 value is between 2-3, meaning that, on average, one infected person goes on to infect at least two others. That R0 value was determined by examining the increase of infection rates in Wuhan, China, during the epidemic’s first phase.
"In creating the statistics model for Finland, the value has been around two or somewhat below that, because [the government] has taken strong measures to limit contact between people," Auranen explained.
On Monday, Prime Minister Sanna Marin and members of her administration declared a national state of emergency, moved teaching online and issued a long list of other measures aimed at curbing the spread of the virus.
Fewer infections, longer-lasting epidemic
If officials had not responded to the epidemic and coronavirus were to be allowed to spread, models show that the disease would have swept across the country as a strong wave that would have lasted for two to three months. In that case, it would reach its peak the first week of April.
Up to half of Finland’s population would be infected, but the majority of cases would be mild.
But now that the government has taken action to thwart the spread of the virus, the statistical models project that the epidemic will weaken but take longer to run its course, according to Auranen.
"The number of infections will be fewer but the epidemic will last longer, by at least three months," he explained.
Two big questions
However, Auranen said considering these statistical models raises two major questions. First, how many infected people have been symptom-free and unaware they even had Covid-19?
He said the answer to that will only clear up once the epidemic is over, after broad tests to determine how many people actually had been infected.
The second question relates to how the virus is being carried and transmitted by children. In the case of the normal seasonal flu, children tend to get infected and spread it onwards.
"The [coronavirus] infections among children have been mild and that’s why we don’t have very much information about how the virus is spread among them. The worst possible scenario would be that children can infect others as easily as adults," he said.
Academic: 'Closing schools not as drastic as it sounds'
The Finnish Institute for Health and Welfare THL is working to create its own statistical models that will track the length and severity of the coronavirus epidemic. But many questions remain about how government’s interventions announced on Monday will affect the outbreak.
Some answers to those questions can be seen in research compiled by Auranen and his colleagues about 12 years ago, data which has been examined quite a bit this week, according to the professor. One data set, based on a survey, shows how many contacts each Finnish resident has to others in various age groups.
"Based on that material, the decision to close schools, for example, is not as drastic as it sounds. The effects of limiting contact [between people] depends on the number of other contacts that a child might have, for example if they stay home or head to their grandparents," Auranen said.
The spread of coronavirus can also be modelled through microsimulation, computerised analytical tools that can be used to theoretically evaluate the effects of interventions before they are carried out. Using such methods, which Finland already has done to examine coronavirus’ spread, the infections can be calculated at the family and workplace levels.
Hope from China
An model explaining how coronavirus initially spread in China, which was published (siirryt toiseen palveluun) at the beginning this month, showed encouraging signs that government interventions - as well as the public’s own initiatives - were effective in fighting the epidemic. The model calculated three alternative scenarios for the epidemic in Wuhan, China.
According to the model, if the spread of coronavirus had been left to run its course, the epidemic in China would have reached its peak and lasted into summer. In the model’s second scenario, in which people practiced social distancing in an effort to reduce infecting others, the epidemic lasted longer but its peak would be significantly slowed down.
The model’s third scenario - which included the public’s voluntary measures along with government directives like quarantines and curfews - provided the most satisfactory results in fighting the virus’ spread.
According to data from Chinese authorities, the epidemic spread in the Asian country according to the third - and most satisfactory - model. For some time now, the country has been reporting fewer than 100 confirmed new coronavirus infections per day.
UK looks to herd immunity
In the UK however, policymakers have specifically avoided taking the most stringent measures in limiting the spread of coronavirus. Instead, they are planning a controlled spread of the disease, hoping to establish herd immunity across the country.
"Humans likely have no immunity to coronavirus. In the UK, at least so far, efforts have been made to create herd immunity in the eventual case that coronavirus does not go away after the pandemic," Auranen said.
During Monday’s government press conference, Prime Minister Sanna Marin was asked about Finland’s position regarding the UK’s herd immunity strategy.
Marin answered by saying that Finland was not following that approach. She added that the country makes decisions based on the current situation and the recommendations of experts.