Last week I wrote about a study from the UK which found that coronavirus antibodies only seemed to last a few months in the body. As I explained at the time, that study was far from conclusive because it was only looking at one type of immunity (that given by antibody production). The study did not look at another type of immunity (that provided by T-cells) which may turn out to be more important for providing immunity to the virus. The Atlantic published a piece yesterday in which experts suggested we probably shouldn’t read too much into the antibody study.

However, what would be worrisome is if we start seeing people get reinfected after recovering. That would suggest that, at least for some people, immunity to the virus really isn’t lasting very long. On that point, last week I pointed out this piece at Vox in which a doctor described a patient who apparently got the virus a second time. The doctor couldn’t confirm that this wasn’t a case of a lingering infection but he was clearly worried about the possibility of reinfection and what it might mean for our natural immunity to the virus.

Today, the Jerusalem Post published a similar story about a doctor at a hospital in Israel who may have been reinfected:

The doctor suffered from fever, cough and muscle pain when she tested positive for the virus in April, but she recovered and tested negative in May and June.

Earlier this month, she came in contact with a confirmed patient and subsequently tested positive for the virus.

The cases are the latest in a series of incidents of suspected reinfection that have raised questions concerning how long immunity against the virus lasts.

That certainly sounds like a case of reinfection but a spokesman for the hospital said the doctor, “tested positive again because she has remnants of her first virus still floating around in her body.” So the hospital seems to be suggesting this was not a new infection but a lingering one.

There are a handful of other cases like this. A news station in Colorado produced this story about a woman named Michelle who tested negative several times and then tested positive again.

In Michelle’s case, this sounds less like reinfection and more like a lingering infection. She says in the clip above that even when she tested negative some of her symptoms persisted. So maybe this is just a case of false negatives in the testing, though obviously the doctor interviewed for this story isn’t willing to rule out reinfection as a possibility.

So far these cases seem rare enough that they could be flukes, i.e. false negatives. We’ll have to keep an eye out to see if, as time passes, more of the people who had the virus early on complain about getting it a second time. If the number of these cases remain very small we probably don’t have to worry too much. If however this sort of report becomes more common that might suggest bad news about the duration of immunity.