“When we go sort of into the second phase, the rapid finding of what could be a potential cluster, is going to be crucial,” Tegnell said.
Since March, he said, the “cluster-like” and “haphazard” spreading pattern of the disease had become increasingly clear, underlining “how important it is to keep some kind of vigilance around finding those clusters early on, and taking them on very rapidly”.
“Now of course, that means that you need to have testing in place, and that you need to have quick contact tracing to understand if you have a developing cluster or not.”
Tegnell's call for increased testing follows a dramatic 34 percent fall in the number of tests carried out in Sweden over the past five weeks, from 79,811 in the last week of June to 52,959 the week before last.
At the same time, the Public Health Agency of Sweden announced on July 20th that helping with the tracking and tracing contacts would in Sweden could in future be partly carried out by the infected individuals themselves, rather than necessarily carried out by health professionals or trained tracers.
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Rapid decline in cases
Tegnell said that the three weeks he took off on holiday at the start of July had marked a turning point for the pandemic in Sweden.
“When I left, we were still on this kind of plateau that we had been on for some time,” he said. “But during during those three weeks, this rapid decline in cases started… and exactly why this happened at that time and why it was so quick suddenly, I think it's a little bit difficult for us to completely understand.”
He said that the drop did not seem connected to the summer holidays, or to any measures taken by health authorities.
“It was long after school break-up, and a little bit more than half way through for most people's holidays,” he said. “We believe that the increasing number of immune people in the population has had something to do with it, but how important that is, we don't really know.”
Sweden at the end of May reported the highest per capita death rate from coronavirus, on a rolling seven-day average, in the world. Since then the rolling seven-day average death rate has fallen from 6 per million to 0.28 per million on Sunday, according to OurWorldInData.
According to the latest statistics, 5,763 have died of coronavirus in Sweden, almost five times as many people as have died in Denmark, Norway and Finland put together.
But Tegnell argued that the drop in cases in July had shown that Sweden's strategy, which has avoided most of the strictest measures imposed in many other European countries, had in some ways succeeded. The growing number of cases in many other countries, meanwhile, was casting doubt over whether they would be able to keep infection rates to the low figures achieved during lockdowns.
“The figures in Sweden show that you can get a rapid decline of cases without having a lockdown. How this will play out in the long run, we don't really know yet, and I think it's more uncertain now than it was for a while when we see the currents in many countries in Europe.”
In addition, Tegnell said Sweden's recent successes in keeping the pandemic out of elderly care facilities showed that the central plank of its initial strategy — to protect the elderly and high risk — was technically possible, even through Sweden had failed disastrously to implement it in March and April.
“We have hardly any cases at all in the long-term care facilities anymore, and that happened long before the rapid decline of cases,” he said. “So that shows that it's quite possible — even with a strategy like the Swedish one — to keep the disease to a high extent outside of the elderly care homes.”
“We have a slight increase of cases, among the 19 to 30 year olds, which you see in many countries in Europe, but it's not very big and it still seems to be manageable.”
Second wave 'unlikely'
Looking forward to the future, Tegnell said he did not expect Sweden to be hit by a second wave of infection on the scale of that seen in April and May.
“I think the most likely [scenario] is that we continue to have a spread in society, but on a low level — hopefully even lower than we have now. But then there is always the risk of outbreaks here and there,” he said.
“I do not believe that we're going to have huge outbreaks. But we are most likely also going to have outbreaks in similar ways that many other countries have had in certain situations and certain workplaces and so on.
“And therefore, we think it's extremely important for the regions to have a high level of preparedness to find these ones and to handle them quickly. So they don't have to become the beginning of a new major spread of the disease.”
Tegnell said that the new scenario of sporadic local outbreaks might also mean restrictions should be applied at a local rather than a national level.
“I think local measures will be the thing of the future in many countries. Since we have seen how the disease is acting very much locally, then it doesn't really make sense to have measures that affect the whole country,” he said.
But he said Sweden would nonetheless keep in place most of the national measures it imposed in March and April, such as its ban on gatherings with more than 50 people, and restrictions on visiting elderly care facilities.
Sweden, he said, aimed from the start to put in place measures that could remain for the duration of the pandemic, judging that imposing and removing restrictions as case levels fluctuate would cause unnecessary disruption.
“We believe that lifting and closing things is really detrimental to trust and also has a lot more negative effects than than keeping some level of measures in place all the time,” he said.
A group of people protesting outside the Public Health Agency's building. Photo: Fredrik Sandberg/TT
When asked what the world had learned about coronavirus since March, Tegnell highlighted doctors' growing awareness of the sheer range of illnesses it can cause.
“I think one of the things we [now] know is that this is a very unpredictable disease, both in the way it spreads but also the kind of illnesses it causes,” he said.
“It has really shown that it can cause a wide variety of symptoms and problems, that was not so apparent in March. So I think I definitely have a different kind of respect for the disease.”
Antibodies and immunity
A study from Sweden's Karolinska Institute
at the end of June indicated that as many as twice as many people who test positive for coronavirus antibodies may have in fact had the illness, with other developing only T-cell immunity.
But Tegnell said that he believed that balance of research was now pushing back in the other direction.
“It seems like we're more and more going back to, 'if you just measure antibodies, three to four weeks after you've been ill, really mostly most people do develop antibodies',” he said.
He said that the lower than expected proportion of people in Sweden testing positive for antibodies more likely reflected problems collecting a representative sample of the population.
“I think the problem more with the low levels [of participants] in the different investigations is that it's very difficult to draw a good sample from the population, because obviously, the level of immunity differs enormously between different age groups between different parts of Stockholm and so on,” he said.
“That's why when we measure one group we get to four percent to five percent, and when we measure another group they're up to 25 percent. Personally, I feel more and more frustrated about ever getting a true sample of what's true level of immunity in a population.”
If the fall in the number of cases in July reflected immunity rather than some as yet unidentified factor, he said, it would indicate that the level of immunity in Sweden was much higher.
“The data is not very solid, but it would probably say that we are in the range of between 20 percent and 30 percent, maybe even slightly more in the areas that it was most prevalent, but this is very much us guessing.”