SHIRLEY DE VILLIERS: Why SA needn’t fear reinfection - maybe
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Another week, another coronavirus curveball.
On Monday scientists announced the first confirmed case of Covid reinfection: a 33-year-old man returning to Hong Kong from Spain had tested positive for the virus, 41⁄2 months after his first bout with Covid-19.
Within days, that finding was echoed in Belgium and the Netherlands.
If the possibility of reinfection was news to those whose lives were on pause pending the immunity a vaccine would offer – or those basking in the hallowed, post-Covid glow of immuno-privilege – it was less of a surprise for experts.
As Megan Molteni and Gregory Barber point out on news website Wired (, immunologists have been waiting to see if immunity to SARS-CoV-2 will wane. Respiratory viruses, coronaviruses among them, apparently often carry the possibility of reinfection.
Now we know.
While this may change the game when it comes to predictions around herd immunity, it’s not all bad news, say Molteni and Barber.
The reinfected patient was completely asymptomatic on his second infection, leading the Hong Kong scientists to note that though “it is unlikely that herd immunity can eliminate SARS-CoV-2 ... it is possible that subsequent infections may be milder than the first infection, as for this patient”.
Of course, you can’t draw any definitive conclusion from a single case in a universe of almost 24-million confirmed infections, as Molteni and Barber make clear. But their article provides an interesting overview of immunity and Covid, and the red flags the Hong Kong case raises around further transmission.
They also suggest that hopes for “sterilising immunity” – where a disease elicits a strong enough response from the immune system to confer lifelong immunity – may have been a tad optimistic.
How to exit the pandemic
It’s a sentiment echoed by Helen Branswell, on health website Stat News, where she lays out four possible scenarios ( around Covid-19 immunity and our exit from the pandemic.
“Sterilising immunity” is unlikely to arise through infection, she says, and it’s also unlikely to be triggered by a vaccine.
If the vaccine works for humans as it does for primates in vaccine studies, people could still pick up and transmit the virus – “but the type of Covid-19 disease that lands people in ICUs and that sometimes kills them would be prevented”.
The more likely scenario, then, is of “functional immunity”, where the immune system of a person exposed to the virus (through either ...
On Monday scientists announced the first confirmed case of Covid reinfection: a 33-year-old man returning to Hong Kong from Spain had tested positive for the virus, 41⁄2 months after his first bout with Covid-19.
Within days, that finding was echoed in Belgium and the Netherlands.
If the possibility of reinfection was news to those whose lives were on pause pending the immunity a vaccine would offer – or those basking in the hallowed, post-Covid glow of immuno-privilege – it was less of a surprise for experts.
As Megan Molteni and Gregory Barber point out on news website Wired (, immunologists have been waiting to see if immunity to SARS-CoV-2 will wane. Respiratory viruses, coronaviruses among them, apparently often carry the possibility of reinfection.
Now we know.
While this may change the game when it comes to predictions around herd immunity, it’s not all bad news, say Molteni and Barber.
The reinfected patient was completely asymptomatic on his second infection, leading the Hong Kong scientists to note that though “it is unlikely that herd immunity can eliminate SARS-CoV-2 ... it is possible that subsequent infections may be milder than the first infection, as for this patient”.
Of course, you can’t draw any definitive conclusion from a single case in a universe of almost 24-million confirmed infections, as Molteni and Barber make clear. But their article provides an interesting overview of immunity and Covid, and the red flags the Hong Kong case raises around further transmission.
They also suggest that hopes for “sterilising immunity” – where a disease elicits a strong enough response from the immune system to confer lifelong immunity – may have been a tad optimistic.
How to exit the pandemic
It’s a sentiment echoed by Helen Branswell, on health website Stat News, where she lays out four possible scenarios ( around Covid-19 immunity and our exit from the pandemic.
“Sterilising immunity” is unlikely to arise through infection, she says, and it’s also unlikely to be triggered by a vaccine.
If the vaccine works for humans as it does for primates in vaccine studies, people could still pick up and transmit the virus – “but the type of Covid-19 disease that lands people in ICUs and that sometimes kills them would be prevented”.
The more likely scenario, then, is of “functional immunity”, where the immune system of a person exposed to the virus (through either ...