Exposure to Covid-19 is similar in Stockholm and London, based on antibody tests, despite different lockdown strategies, research suggests.
Sweden chose to avoid a strict lockdown, with shops and restaurants staying open.
Health experts predicted that 40% of the population in the capital, Stockholm, would have developed antibodies to the disease by May.
The actual figure was 17%, according to a review of evidence.
The research, published in the Journal of the Royal Society of Medicine, found that 17% of people tested in April in Stockholm had developed antibodies.
This compares with 17% of Londoners tested in April and May, and 5%-10% of people living in Geneva.
Sweden adopted a lighter-touch strategy for dealing with the pandemic compared with most other European countries, deciding not to institute a widespread lockdown, and putting in place relatively few restrictions.
This was based partly on the idea of letting Covid-19 sweep through the population creating so-called herd immunity. Such an approach was considered but then abandoned in the UK.
In the UK, more than 46,500 people have died in a country of more than 66 million.
In Sweden, there have been more than 5,500 deaths in a country of 10 million, which is one of the highest death rates relative to population size in Europe, and by far the worst among the Nordic nations.
Retired doctor David Goldsmith and Eric Orlowski from University College London wrote: "Lest this strategy seem like just the traditional risky Swedish exceptionalism, we in the UK would do well to remember we nearly trod the same path.
"Right now, despite 'strict (but tardy) lockdown' in the UK, and the more measured Swedish response, both countries have high seven-day averaged Sars-CoV-2 death rates when compared to other Scandinavian and European countries."
But they said that only after the pandemic and the impact of the measures taken were fully understood, after one or two years at least, would it be fair to judge which had been the right approach.
People who catch a virus usually have antibodies, which can be measured by tests.
But it's not clear whether having antibodies offers total, or even partial, protection from catching Covid-19, or how long such an effect may last.
The research suggests the Swedish strategy failed to generate widespread protective immunity, said Dr Simon Clarke of the University of Reading, who is not connected to the study.