A man in Hong Kong has become the world’s first documented case of COVID-19 reinfection since the pandemic emerged from Wuhan, China late last year.
The patient, a 33-year-old information technology (IT) worker, is the subject of a study published in Clinical Infectious Diseases (CID), a peer-reviewed medical journal published by the Oxford University Press (OUP) on behalf of the Infectious Diseases Society of America (IDSA).
“Our results suggest #SARSCoV2 may continue to circulate among the human populations despite herd immunity due to natural infection or vaccination,” says the study by @hkumed Microbiology. #COVID19https://t.co/qcDw9deWdD
— HKU Medicine (@hkumed) August 26, 2020
The patient first tested positive for COVID-19 on March 26. He suffered from a cough, fever, headache and sore throat for three days during this episode of illness.
After testing negative for COVID-19 twice, the patient was discharged from the hospital on April 15. However, he tested positive again after returning to Hong Kong from Spain via the U.K. on Aug. 15.
Unlike his first infection, however, the patient no longer had symptoms the second time. Nevertheless, he was still hospitalized.
“Many believe that recovered Covid-19 patients have immunity against reinfection because most developed a serum neutralising antibody response. However, there is evidence that some patients have waning antibody level after a few months,” researchers from the University of Hong Kong said, according to RTHK.
The coronavirus strains the patient had contracted were “clearly different,” the researchers said. Genetic analyses showed that his first infection came from a strain most closely related to those from the U.S. or England, while his second infection was most closely related to strains from England and Switzerland.
“Our findings suggest that the SARS-CoV-2 may persist in the global human population as is the case for other common cold-associated human coronaviruses, even if patients have acquired immunity via natural infection,” the researchers added. “Since the immunity can be short-lasting after natural infection, vaccination should also be considered for those with one episode of infection.”
This means patients who already recovered from COVID-19 must still wear masks, maintain social distancing and observe other infection control measures. Additionally, they should get the right vaccine if and when one becomes available.
“Immunity induced by vaccination can be different from those induced by natural infection,” Dr. Kai-Wang To, one of the study’s lead authors, told Reuters. “[We] will need to wait for the results of the vaccine trials to see how effective vaccines are.”
Akiko Iwasaki from the Yale School of Medicine, who was not involved in the study, noted that natural infection may not provide herd immunity, considering that reinfection can occur. For this reason, she also supports the idea of vaccination.
“The only safe and effective way to achieve herd immunity is through vaccination,” Iwasaki tweeted. “Lastly, while this is a good example of how primary infection can prevent disease from subsequent infection, more studies are needed to understand the range of outcomes from reinfection.”
Two more cases of COVID-19 reinfection were made public following the Hong Kong report. They are in Belgium and the Netherlands, according to EuroNews.
To date, there have been 23.9 million cases of COVID-19 worldwide, according to data compiled by Johns Hopkins University. The global death toll stands at over 820,000.
Feature Image via Getty