As if there's not enough about COVID-19 to worry about.

By Claire Gillespie
Updated May 11, 2020
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We all have a million and one questions about the new coronavirus. When it comes to whether you can get COVID-19 twice, or if you become immune to it, there’s not a simple answer. 

Concerns that people could get the coronavirus, recover, and then become reinfected have grown since it was reported that patients in China who had two negative tests and were discharged from a hospital subsequently had to be readmitted because they tested positive later.

“According to current protocols, patients who test positive for the coronavirus and are hospitalized must have two negative tests obtained 24 hours apart prior to discharge,” Mahmoud Loghman-Adham, MD, a principal at California-based life sciences consulting firm Innopiphany, tells Health. “In the case of the Chinese patients, the patients had no symptoms and were showing signs of improvement.”

Another patient, from Japan, reportedly also developed symptoms and tested positive for COVID-19 a second time, after being given the all-clear.  

It’s understandable that people are worried about getting a serious disease twice and requiring repeat hospitalizations and/or quarantine. While experts still don’t know a lot about COVID-19, they do have deeper knowledge of similar viral diseases.

“In general, patients make antibodies to viruses and become immune to a repeat infection from the same virus,” explains Dr. Loghman-Adham. 

Most current testing for the coronavirus is based on polymerase chain reaction (PCR) amplification, which measures the number of copies of RNA (ribonucleic acid, a nucleic acid present in all living cells) the virus produces. 

“The test can just confirm that viral RNA is present in large amounts, but this RNA can be a small piece of the viral RNA and thus unable to cause infection,” says Dr. Loghman-Adham. “The test would thus be ‘false positive,’ especially if the virus copy numbers are less than a certain threshold.”

Collecting samples from multiple sites on the body, such as the nose, throat, stools, and blood, will increase the chance of detecting the virus RNA. But this is only performed for research purposes. 

“To know whether the samples contain infectious viruses, they are placed into a Petri dish containing special cells and the cells are allowed to grow and multiply. If infectious viruses are present in a sample, the cells will become infected and die,” explains Dr. Loghman-Adham. “The test is cumbersome and time-consuming, and it can also expose the technicians to a dangerous virus.”  

A new test, which looks for proteins, or antigens, to SARS-CoV-2, the virus that causes COVID-19, promises to speed up the process. The US Food and Drug Administration on May 8 granted emergency use of an antigen test developed by San Diego-based Quidel Corporation that is capable of diagnosing the illness in 15 minutes, according to the company.

It’s scary to read news reports with headlines that fuel the already rampant COVID-19 anxiety. But remember, news reports aren’t scientific studies, no test is perfect, and everyone’s immune system is different. 

The bottom line? “Based on all that we know so far, once you have the COVID-19 infection, you can’t get it again,” says Dr. Loghman-Adham. “But there are always exceptions."

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDCWHO, and their local public health department as resources.

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