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Soon after the first patients began to recover during the initial
outbreak of COVID-19 in Hubei Province, China, researchers in the area
noticed something both peculiar and frightening. A portion of those who
initially tested positive, then were sent home after receiving a
negative test result, were turning up again with a positive test at a
later date. These results, which in some reports were as high as 15% of
patients, brought into question both the accuracy of tests and even the possibility of a vaccine. After all, if patients could catch COVID-19 over and over, it seemed unlikely any vaccine could provide protection.
That same effect—a patient tests positive, then negative, then positive again—has continued to appear around the world. But there are two reasons to feel more hopeful about what these results mean. First, some of those cases may well have been the result of either false negatives or false positives in testing associated with patients whose viral load was very low. And now, research in Korea indicates that those who generate this “second positive” result may be immune after all.
Better still, they may be incapable of infecting anyone else.
As Bloomberg reports, researchers at the Korean Centers for Disease Control and Prevention studied a group of 285 patients who had received at least one negative test result after recovering from COVID-19, then received a positive result at a later date. Their conclusion was that these “re-positive” patients were not only not contagious, but immune.
When samples of virus were taken from these patients, it would not reproduce in the lab. What was generating the positive result doesn’t appear to be live virus … but dead virus. So these patients had apparently developed an immune response that allowed them to fight off reinfection, and were not carrying virus that could infect others.
This is fantastic news on all fronts.
On April 25, the World Health Organization warned against governments who were considering giving out “immunity passports” to those carrying antibodies against the SARS-CoV-2 virus. That warning came in part because it’s unclear what level of antibodies provides a high degree of protection against COVID-19 and because many of the antibody tests have so far not been sufficiently validated. However, it also came because the re-positive cases seemed to suggest that some patients were possibly open to reinfection. Giving a free pass to travel based on the results of an antibody test could have been a license to spread coronavirus even more broadly. If the results of the Korean study can be confirmed, much of that concern can be set aside … though the concern about inaccurate antibody tests remain.
Even more importantly, this result would seem to validate the idea that it is possible to acquire and sustain an effective immunity to COVID-19. That’s a critical factor if there is any hope that a vaccine can put a definitive period at the end of the pandemic.
And the results that are being reported here likely extend to numerous stories that have appeared in the media of patients “shedding virus” weeks after infection. That may be the case. But shedding dead virus, or the remnants of virus broken up by the immune system, is no threat to anyone.
As a result of these tests, South Korean authorities will no longer
require those who have tested negative after recovering from COVID-19 to
take additional tests to confirm their status before returning to work,
school, or travel. Which means that re-positive cases in South Korea
are going to be way down … since these patients will generally not be
tested. Because, so far as researchers there are concerned, these people
are not a threat. That same effect—a patient tests positive, then negative, then positive again—has continued to appear around the world. But there are two reasons to feel more hopeful about what these results mean. First, some of those cases may well have been the result of either false negatives or false positives in testing associated with patients whose viral load was very low. And now, research in Korea indicates that those who generate this “second positive” result may be immune after all.
Better still, they may be incapable of infecting anyone else.
As Bloomberg reports, researchers at the Korean Centers for Disease Control and Prevention studied a group of 285 patients who had received at least one negative test result after recovering from COVID-19, then received a positive result at a later date. Their conclusion was that these “re-positive” patients were not only not contagious, but immune.
When samples of virus were taken from these patients, it would not reproduce in the lab. What was generating the positive result doesn’t appear to be live virus … but dead virus. So these patients had apparently developed an immune response that allowed them to fight off reinfection, and were not carrying virus that could infect others.
This is fantastic news on all fronts.
On April 25, the World Health Organization warned against governments who were considering giving out “immunity passports” to those carrying antibodies against the SARS-CoV-2 virus. That warning came in part because it’s unclear what level of antibodies provides a high degree of protection against COVID-19 and because many of the antibody tests have so far not been sufficiently validated. However, it also came because the re-positive cases seemed to suggest that some patients were possibly open to reinfection. Giving a free pass to travel based on the results of an antibody test could have been a license to spread coronavirus even more broadly. If the results of the Korean study can be confirmed, much of that concern can be set aside … though the concern about inaccurate antibody tests remain.
Even more importantly, this result would seem to validate the idea that it is possible to acquire and sustain an effective immunity to COVID-19. That’s a critical factor if there is any hope that a vaccine can put a definitive period at the end of the pandemic.
And the results that are being reported here likely extend to numerous stories that have appeared in the media of patients “shedding virus” weeks after infection. That may be the case. But shedding dead virus, or the remnants of virus broken up by the immune system, is no threat to anyone.
Not a threat to get COVID-19.
Not a threat to spread it.
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