Is it actually possible to test positive for the new coronavirus disease (COVID-19) again after recovering from a previous bout of the same illness?
A woman who works as a tour bus guide in Osaka, Japan was said to have again tested positive for the coronavirus weeks after recovering and being released from a hospital.
In San Antonio, Texas, a woman who was released from quarantine after testing negative for the coronavirus twice tested positive after a third test. This prompted San Antonio Mayor Ron Nirenberg to declare a public health emergency after it was discovered that the woman — one of 91 American evacuees from Wuhan, China — visited a hotel and a shopping mall after being released.
In addition to these two cases, coronavirus reinfections have also been reported in South Korea and in several cities in China, where the outbreak began in December of 2019.
Health officials at the Centers for Disease Control and Prevention (CDC), however, continue to maintain that reinfection is “unlikely” despite the growing number of such cases worldwide.
So, what exactly is going on here?
According to experts, a number of these “reinfections” may be attributed to poor testing.
Lei Xuezhong, deputy director of the West China Hospital’s infectious diseases center, mentioned that hospitals in China were previously testing nose and throat samples to decide whether patients should be discharged. More recent tests, however, have found traces of the virus in the lower respiratory tract as well.
Experts also believe that some discharged patients could still be carrying low levels of the virus, which tests may have failed to detect.
Paul Hunter of the University of East Anglia in Norwich, England told the press in an interview that while it is possible that the woman in Osaka may have been reinfected, it is also likely that the virus from her initial infection was still being released into her system.
Polymerase chain reaction (PCR) tests done to four medical professionals in Wuhan who were previously exposed to the virus still found traces of the viral genetic material of the coronavirus despite being asymptomatic for one to two weeks. This particular test, however, is highly sensitive and could detect genetic material even from a single molecule.
Another possible explanation for these “reinfections” is that samples were not being properly stored. Some samples may have been kept at a temperature which could cause the virus to deteriorate.
One worrying possibility that is also being looked into is that the coronavirus could be biphasic, which means that the virus could be dormant for a while before causing a new set of symptoms. Experts, however, still do not know enough about the virus to make such a conclusion.
Meanwhile, scientists say that those who have been infected by the coronavirus produce antibodies that could protect them from the same virus later on.
Song Tie of the local disease control center in China’s Guangdong province believes that once these antibodies have been produced, the infected person will no longer be contagious. He also says that none of the “reinfected” patients appear to have infected anyone else.
Adam Kamradt-Scott of the University of Sydney said that in most cases, the second infection is usually less severe since the patients’ bodies have already developed an immune response to the initial infection.
Dr. Stanley Perlman of the University of Iowa said that the new coronavirus resembles the coronavirus that caused the SARS and MERS outbreaks. He also said that there were no reports of a SARS reinfection, and he has only heard of one MERS patient being reinfected.
Dr. Perlman’s research on MERS also determined that the severity of the infection would determine the strength of the body’s immune response. In most cases, however, the immunity diminishes within a year.
Should COVID-19 become a seasonal illness like the flu, knowing how long immunity lasts and how often reinfection could occur could play a vital role in developing the vaccine. As the number of infections outside of China continues to grow, scientists would need to work double-time to get all the answers as soon as possible.