Explaining the science behind Sweden’s relaxed coronavirus approach, by Paul Franks, Professor of Genetic Epidemiology, Lund University and Peter M Nilsson, Professor of Internal Medicine – Epidemiology, Lund University.

Unlike its Nordic neighbours, Sweden has adopted a relatively relaxed strategy, seemingly assuming that overreaction is more harmful than under-reaction.

Although the government has now banned gatherings of more than 50 people, this excludes places like schools, restaurants and gyms which remain open. That’s despite the fact that 3,046 people have tested positive. …

In Sweden, the public health authorities have released simulations to guide “surge requirements”. This is the extent to which hospitals will need to boost their capacity to deal with the high number of very ill COVID-19 patients that are likely to need specialist care in the coming weeks. From these simulations, it is clear that the Swedish government anticipates far fewer hospitalizations per 100,000 of the population than predicted in other countries, including Norway, Denmark and the UK. …

The reason appears to be that Swedish authorities believe there are many infected people without symptoms and that, of those who come to clinical attention, only one in five will require hospitalisation. At this point, it is hard to know how many people are asymptomatic as there is no structured screening in Sweden and no antibody test to check who has actually had COVID-19 and recovered from it. But substantially underestimating hospital surge requirements would nevertheless be devastating. ….

There are several arguments supporting the current official Swedish strategy. These include the need to keep schools open in order to allow parents who work in key jobs in health care, transportation and food supply lines to remain at work. Despite other infectious diseases spreading rapidly among children, COVID-19 complications are relatively rare in children. A long-term lockdown is also likely to have major economic implications that in the future may harm healthcare due to lack of resources. This may eventually cause even more deaths and suffering than the COVID-19 pandemic will bring in the near term. …

A century ago, Sweden was recovering from the first world war, even though the country stayed neutral. Internal transportation and communication systems were less developed than in many other countries at the time, which helped slow the spread of the epidemic. In the short term, this was perceived to be a good thing, but because herd immunity — whereby enough people have been infected to become immune to the virus — had not been initially achieved, there were at least two additional epidemics of the Spanish flu virus within a year. The second wave of infections had a higher mortality rate than the first wave.

Learning the lesson from this, many people in Sweden are now optimistic that it can achieve herd immunity. Compared with the Spanish flu, COVID-19 is less severe, with many infected people believed to be asymptomatic. While this contributes to a more rapid spread, it also means that the threshold for “herd immunity” is about 60%. This may be quickly achieved in countries that do not have intensive mitigation or suppression strategies.

Belarus, Brazil and Sweden seem to be taking the herd immunity approach. Their citizens are going be either furious, dead, or sick if it fails, or awesomely smug if it works.

According to Chinese statistics (all dodgy), about 0.0065% of the Chinese population has been infected — so they would require 10,000 times as many people to catch it to achieve herd immunity. China went for the crush-the-curve strategy instead.

No country has got anywhere near herd immunity yet. Once the bodies start piling up in hospital corridors, they go for lockdown.

hat-tip Stephen Neil