CNN  — 

Sweden has revealed that despite adopting more relaxed measures to control coronavirus, only 7.3% of people in Stockholm had developed the antibodies needed to fight the disease by late April.

The figure, which Sweden’s Public Health Authority confirmed to CNN, is roughly similar to other countries that have data and well below the 70-90% needed to create “herd immunity” in a population.

It comes after the country adopted a very different strategy to stop the spread of coronavirus to other countries by only imposing very light restrictions on daily life.

Sweden’s chief epidemiologist Anders Tegnell said the number was a “little lower” than expected “but not remarkably lower, maybe one or a couple of percent.”

“It squares pretty well with the models we have,” he added, while speaking at a news conference in Stockholm.

The study carried out by Sweden’s Public Health Agency aims to determine the potential herd immunity in the population, based on 1,118 tests carried out in one week. It aims to carry out the same number of tests every seven days over an eight-week period. Results from other regions would be released later, a Public Health Authority spokesperson said.

The country has not enforced strict lockdown measures and most restaurants, bars and stores have remained open.

Sweden has adopted a different strategy to other Nordic nations during the pandemic, choosing to avoid a lockdown and keep most schools, restaurants, salons and bars open. It did, however, ask people to refrain from making long journeys, placing an emphasis on personal responsibility.

The strategy was criticized by Swedish researchers early on, who said that attempting to create herd immunity had low support. But the authorities denied that achieving herd immunity was their goal.

Herd immunity is reached when the majority of a given population – 70 to 90% – becomes immune to an infectious disease, either because they have become infected and recovered, or through vaccination. When that happens, the disease is less likely to spread to people who aren’t immune, because there just aren’t enough infectious carriers to reach them.

No community has yet achieved this and a vaccine “will get us to herd immunity quicker” than infection, Michael Mina, Assistant Professor of Epidemiology at Harvard T. H. Chan School of Public Health, said in a recent interview with Public Radio International’s The World.

A healthcare worker cleans and disinfects an ambulance after dropping a patient at the Intensive Care Unit (ICU) at Danderyd Hospital near Stockholm on May 13.

Sweden’s percentage of people with antibodies is not far off that of other countries that did enforce lockdowns. In Spain, 5% of people had developed coronavirus antibodies by May 14, according to preliminary results of an epidemiological study by the government.