'What Does It Mean That Someone Has Caught COVID-19 For a 2nd Time?'
'What does it mean that someone has caught COVID-19 for a 2nd time? Mark Sumner, Daily Kos, Aug. 25, 2020. - Ed.:
Since the early infection period in China, there were reports that some people had been reinfected with the virus behind COVID-19 after apparently recovering from the disease. Some of the early numbers suggested that the reinfection rate was as high as 15%, but that was, and remains, pretty definitely untrue. These early results came from people who had received a series of tests and at some point tested negative before testing positive again. The “reinfection rate” was almost certainly inflated by false results. Either a false positive or a false negative could give the appearance of reinfection, and even a test with a relatively small number of bad results could generate significant amounts of apparent reinfection when the results require a sequence of tests all going right.
Though there have been frequent anecdotal accounts of people developing COVID-19 a 2nd time since then, there’s been very little in the way of genuine evidence. A review of such cases in South Korea showed that, in addition to false test results, in many cases doctors and researchers simply weren’t accounting for how long the SARS-CoV-2 virus can linger in the system. *Meaning that some of the “reinfected” were actually just the “still infected.”
>Now a pre-print of a study out of Hong Kong identifies a single patient, fairly convincingly, of being infected by SARS-CoV-2 twice. This case is getting a lot of attention because it speaks directly to concerns about COVID-19, including concerns that vaccines might not be effective and that people might catch the disease over and over. But the new results actually contain some good news. The case in Hong Kong features a 33-year-old man who was first diagnosed with COVID-19 in March, recovered, then tested positive again after traveling to Europe in July. There are multiple reasons to believe that this genuinely represents a case of reinfection. For one thing, the 4 and a 1/2 month interval between cases is long even for this lingering virus. Even more definitively, tests showed that the patient had been infected by 2 different strains of the virus with a number of genetic differences.
So, what does this tell us? Nothing that was really unexpected. There have been studies for several months now indicating that people who had mild or asymptomatic cases of COVID-19 developed low levels of antibodies against the virus & the level of antibodies drops significantly over a period of 2-3 months. There’s far more to immunity than antibodies. It’s far more important that the body be prepared to manufacture antibodies, & mount other defenses, in case of encountering the virus again, rather than walking around with a full load of antibodies ready to go. We also don’t know yet how much antibody presence is needed to represent a good level of immunity. We know that mild cases produce low levels of antibodies, & those low levels can drop after a few weeks. That seems to be related to what happened with the one Hong Kong patient. The man had only a mild case of COVID-19 the 1st time around, so it’s likely his body never developed a high level of antibody response. 4 and a 1/2 months later, he encountered the virus a 2nd time and was reinfected.
That’s clearly not good—in the sense that it would be great if everyone, even asymptomatic carriers—developed an immune response that would provide a lifetime of protection. But there are reasons why it’s far from terrible...
*Read More, https://www.dailykos.com/stories/2020/8/25/1972114/-What-does-it-mean-that-someone-has-caught-COVID-19-for-a-second-time
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