Sweden's 'herd immunity' hopes are fading as only a small fraction of the population has coronavirus antibodies

• Just 6.1% of the population of Sweden had developed coronavirus antibodies by late May, a lower measure than some of its health agency's earlier models had predicted.
• Unlike most European countries, Sweden did not impose a strict lockdown and kept open schools, restaurants, and bars, relying instead on citizens to enact voluntary social distancing measures.
• Sweden did not impose a strict lockdown unlike most European countries and kept open schools, restaurants, and bars, relying instead on citizens to enact voluntary social distancing measures.
• Anders Tegnell, the country's chief epidemiologist, admitted that fewer people had developed antibodies than health authorities had predicted.
• In April, he told the Financial Times that he expected 40% of people in Stockholm, the capital, to be immune to Covid-19 by the end of May.

Sweden's soft approach to the coronavirus has resulted in only a small portion of the population developing antibodies to the virus. This means the country appears highly unlikely to tackle the virus by achieving herd immunity.

A new study published this week showed that just 6.1% of Sweden's population had developed coronavirus antibodies by late May, a lower measure than some of its health agency's earlier models had predicted.

Sweden did not impose a strict lockdown unlike most European countries and kept open schools, restaurants, and bars, relying instead on citizens to enact voluntary social distancing measures.

Health officials have insisted that is not the specific goal of its approach, which they said is designed to prevent a second wave and slow the virus enough for health services not to become overwhelmed, Reuters reported.

But the country's highly controversial approach has become associated with the herd immunity strategy, given that its government expected a large part of its population to become infected with the disease.

Anders Tegnell, the country's chief epidemiologist, told the Financial Times in April that he expected 40% of people in Stockholm, the capital, to be immune to Covid-19 by the end of May.

But the 6.1% figure shows that it is very far off achieving even partial herd immunity, which epidemiologists expect would require at least 60% of the population to become immune to the coronavirus, according to a New York Times report. Once that proportion of a population is infected, the disease has very low transmission because people with antibodies are immune and do not pass it to others.

"The spread is lower than we have thought but not a lot lower," said Anders Tegnell on Thursday, according to Reuters.

"We have different levels of immunity on different parts of the population at this stage, from 4% to 5% to 20% to 25%."

Sweden's coronavirus death toll surpassed 5,000 this week, meaning its mortality rate per capita is very significantly higher than its neighboring Scandinavian countries as well as one of the highest in the world.

Update: An earlier version of this article linked to research suggesting that 90% of the population would need to acquire antibodies against the coronavirus, but the research described the level required for measles rather than coronavirus.