Channel 13 Israel reported that a doctor at Ramat Gan’s Sheba Medical Center first came down with the virus in April, according to the Times of Israel, while she tested negative for COVID-19 in May and June. Now, after reportedly coming in contact with an infected individual, she has again tested positive. While doctors have observed antibodies in many patients immediately following the disease, there is concern that they may not last long in the body, or that some patients may not naturally develop antibodies at all.