Nog veel meer immuniteit-ontkenners, maar dan gekoppeld aan Zweden.
fc
How Did Sweden Flatten Its Curve Without a Lockdown?
One expert credits a "good-enough strategy"; others worry that it won't last
Despite never implementing a full-scale lockdown, Sweden has managed to flatten its curve, prompting its health leadership to claim victory -- but others question the cost of the strategy, as the country has a far higher death toll than its Scandinavian neighbours.
In late July, Sweden's 7-day moving average of new cases was about 200, down from a peak of around 1,140 in mid-June. Its daily death totals have been in the single digits for two weeks, well below its mid-April peak of 115 deaths in a single day.
However, on a per-capita basis, Sweden far outpaces its Scandinavian neighbours in COVID deaths, with 567 deaths per million people compared with Denmark's 106 deaths per million, Finland's 59 deaths per million, and Norway's 47 deaths per million. The Swedish figure is closer to Italy's 581 deaths per million.
While the positive trends have led Anders Tegnell, PhD, chief epidemiologist at the Swedish Public Health Agency and architect of Sweden's coronavirus strategy, to state that the "Swedish strategy is working," others have criticized the approach, including two dozen Swedish academics who published a recent USA Today editorial.
"In Sweden, the strategy has led to death, grief, and suffering," they wrote. "On top of that, there are no indications that the Swedish economy has fared better than in many other countries. At the moment, we have set an example for the rest of the world on how not to deal with a deadly infectious disease."
The Swedish Public Health Agency has not openly stated that herd immunity was its goal, though many suspect this was the intention. Tegnell told reporters last week he thought the recent trends indicated that immunity was now widespread in the country. But with rates of antibody positivity around 10%, that seems impossible. (Officials at the agency did not respond to MedPage Today's request for comment.)
So how has Sweden managed to get its outbreak under control?
Behavior Change
While Sweden didn't officially lock down, many in the country have described a locked-down "feeling" that has eased in the summer months.
At the start of the outbreak, only high schools and universities closed; daycare and elementary schools have been open. Businesses have also remained open, but typically at reduced hours, and restaurants have functioned at reduced capacity.
Swedes have been asked to keep their distance in public, refrain from non-essential travel, and work from home when possible. Gatherings of more than 50 people are also banned. People age 70 and over are advised to stay away from others as much as possible.
Masks were never required and aren't commonly worn.
This response hasn't changed over time, through the June surge and into today's decline, so there's no definitive explanation for the flattening, though, and experts have several theories.
"Swedes in general have changed their behavior to a great extent during the pandemic and the practice of social distancing as well as physical distancing in public places and at work has been widespread," said Maria Furberg, MD, PhD, an infectious diseases expert at Umea University Hospital in northeastern Sweden.
"During the months of March to early June, all shops were practically empty, people stopped dining with friends, and families stopped seeing even their closest relatives," Furberg told MedPage Today. "A lock-down could not have been more effective. Handwashing, excessive use of hand sanitizers, and staying home at the first sign of a cold became the new normal very quickly."
Mozhu Ding, PhD, an epidemiologist at the famed Karolinska Institute, said the decline is "likely to be a combination of measures taken by individuals, businesses and a widespread information campaign launched by the government."
"Even without a strict lockdown order, many businesses allowed employees to work from home, and universities are offering distance courses to the students," Ding told MedPage Today. "Individuals are also taking personal hygiene more seriously, as items like hand sanitizers and single-use gloves are often sold out in pharmacies and grocery stores."
Immunity
Experts told MedPage Today there weren't clear data to prove Tegnell's assertion of widespread immunity in Sweden.
Furberg said there is likely "some sort of unspecific immunity that protects parts of the population from contracting COVID-19" but it's not necessarily secondary to SARS-CoV-2 exposure.
For instance, a study by the Karolinska Institute and Karolinska University Hospital recently found that about 30% of people with mild or asymptomatic COVID showed T-cell-mediated immunity to the virus, even though they tested negative for antibodies.
"This figure is [more than] twice as high as the previous antibody tests, meaning that the public immunity to COVID-19 is probably much higher than what antibody studies have suggested," Ding told MedPage Today. "This is of course very good news from a public health perspective, as it shows that people with negative antibody test results could still be immune to the virus at a cellular level."
Indeed, T-cell immunity is coming into focus as a potentially important factor in COVID infection. A paper published in Nature in mid-July found that among 37 healthy people who had no history of either the first or current SARS virus, more than half had T cells that recognized one or more of the SARS-CoV-2 proteins.
Another 36 people who had mild-to-severe COVID-19 were all found to have T-cell responses to several SARS-CoV-2 proteins, and another 23 people who had SARS-CoV-1 (the virus responsible for the SARS outbreak in 2003) all had lasting memory T cells -- even 17 years later -- that also recognized parts of SARS-CoV-2.
It could be that T cell immunity is the result of a previous infection with common cold coronaviruses, but this hasn't yet been established; nor is it certain that T cell immunity is driving Sweden's decline in COVID cases.