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A key member of the White House coronavirus task force says people who recover from COVID-19 will likely be immune to the virus that causes the disease if a second wave spreads through the U.S. in fall.

While speaking with Journal of the American Medical Association editor Howard Bauchner Wednesday, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), said that because the virus doesn’t seem to be mutating much, it’s unlikely people will test positive a second time.

“Generally we know with infections like this, that at least for a reasonable period of time, you’re going to have antibodies that are going to be protective,” Fauci said.

“If we get infected in February and March and recover, next September, October, that person who’s infected — I believe — is going to be protected,” he added.

Researchers are not sure at this time how long immunity to the coronavirus that causes COVID-19 lasts since it’s a new virus.

A second wave of the novel coronavirus that has infected more than 430,000 and killed more than 14,800 people in the U.S. is a real concern for top health officials.

Dr. Deborah Birx, the White House coronavirus response coordinator, warned Wednesday that Americans need to continue to adhere to social distancing practices to avoid another wave of COVID-19 infections.

“If people start going out again and socially interacting, we could see a very acute second wave very early. We are really encouraging every American to continue to follow the guidelines for these 30 days,” Birx told NBC’s “Today” show Wednesday.

Fauci late last month predicted there would be another coronavirus outbreak in the fall, but said he expects the U.S. to be better able to combat the virus.

But while Fauci said reinfection seems to be unlikely, research out of several countries hit hard by COVID-19 has reported patients who have recovered from infection and later test positive.

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The Korea Centers for Disease Control and Prevention (KCDC) said in a statement a formal investigation was underway looking into dozens of patients that reportedly tested positive for the disease for a second time.

“While we are putting more weight on reactivation as the possible cause, we are conducting a comprehensive study on this,” KCDC Director-General Jeong Eun-kyeong said, according to Bloomberg. “There have been many cases when a patient during treatment will test negative one day and positive another.”

Similar reports have come out of China, where the virus emerged late last year, and Japan in February reported a woman tested positive for the coronavirus a second time.

But some researchers say reinfection is an unlikely explanation for patients who test positive twice, and note the possibility that testing errors, and releasing patients from hospitals too early, are more likely to be the cause of patients who retest positive.

“If you get an infection, your immune system is revved up against that virus,” Keiji Fukuda, director of Hong Kong University’s School of Public Health, told The Los Angeles Times in March. “To get reinfected again when you’re in that situation would be quite unusual unless your immune system was not functioning right.”

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