A 33-year-old man in Hong Kong tested positive for SARS-CoV-2 again, over four months after his initial infection.
Throughout the pandemic, hospitals worldwide have reported positive tests post-recovery, sparking debate: Can COVID-19 strike twice? Experts like virologist Florian Krammer from Icahn School of Medicine at Mount Sinai initially favored explanations of lingering viral fragments rather than true reinfection.
'I'm not saying reinfection is impossible, but in this short time it's unlikely,' Krammer told the New York Times in May. 'Even mild infections should confer short-term immunity.'
The WHO addressed these concerns reassuringly, attributing positives to 'remnants from the lungs during recovery.'
Hong Kong researchers announced the world's first confirmed reinfection on Monday, as detailed by the New York Times. Genetic analysis confirmed a distinct strain from the original infection four months prior—not residual virus.
The patient, returning from Spain via the UK, was flagged at Hong Kong airport. Unlike his symptomatic first bout (cough, headache, sore throat, fever), this infection was asymptomatic.
Genetic sequencing revealed two different SARS-CoV-2 strains.
Unlike SARS and MERS, which offer years-long immunity, this case suggests SARS-CoV-2 may evade lasting protection. 'Our findings indicate SARS-CoV-2 may persist in populations, similar to common cold coronaviruses,' the researchers note.
Herd immunity appears unlikely to eradicate it, though subsequent infections may be milder, per their study accepted in Clinical Infectious Diseases. They recommend vaccination even for prior cases, as immunity may wane quickly.
Experts like Dr. Jeffrey Barrett of the Wellcome Sanger Institute caution: 'One case doesn't yield definitive conclusions, especially given global infection numbers.'
