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How Did Sweden Flatten Its Curve Without a Lockdown?
— One expert credits a "good-enough strategy"; others worry that it won't last
— One expert credits a "good-enough strategy"; others worry that it won't last
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.
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.
More on link below...