SHIRLEY DE VILLIERS: Why SA needn’t fear reinfection — maybe
There are more than 160 Covid vaccines in development, and 21 at clinical trial stage. But don’t hold your breath for equitable, rational distribution ...
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, 4½ 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 illness or vaccination) kicks into gear on reinfection, making for a shorter illness, potentially lower transmission, and a more manageable pandemic.
Further down the desirability scale are “waning immunity”, where the immune response generated by infection or vaccination is lost over time, and – thought to be least likely – a scenario in which immunity is completely lost and reinfection is as severe as the initial illness.
If the experts Branswell canvassed for her article are correct, she adds, the Covid threat should wane over time. “Our immune systems will know how to deal with it. It could become the fifth human coronavirus to cause common colds.”
It’s a comforting thought – and one that makes the search for a vaccine all the more crucial.
More good news is that, by early July, there were already more than 160 vaccine candidates in development, and 21 in clinical trials. And – if you’re prepared to take a chance on former KGB spook turned Russian strongman Vladimir Putin – there’s already a government-approved vaccine in Russia. (More on that from the Daily Beast here, and New Scientist here, but suffice to say scientists, and Russians themselves, seem to be giving it a wide berth.)
Not so fast
It’s not all going to be smooth sailing, and Thomas J Bollyky and Chad P Bown sound a warning against “vaccine nationalism” in Foreign Affairs (the article is free to read, but you have to register for the site).
In the absence of international co-operation to ensure equitable access to effective vaccines – and without some mechanism of enforcement – countries will prioritise the provision of the vaccine to their own people.
The consequences could be dire all round, but particularly for poor and middle-income countries, and could drag out the pandemic and drive up the death toll.
Bollyky and Bown paint a picture of a Hobbesian future: bidding wars drive up vaccine prices; governments seize vaccine stocks; deaths rise as fragile health-care systems and economies in non-vaccine-manufacturing countries collapse; the vaccine manufacturing chain breaks down as countries, seeking leverage, withhold critical vaccine components by blocking exports; poor countries strike short-term deals to secure vaccine stock, with deleterious long-term consequences for themselves and for international co-operation more generally.
It’s bleak stuff – and a crucial issue to deal with now.
While some global leaders have touted vaccines as a “public good” that should be available to all, the reality is that initial supplies will be limited, given a limited number of manufacturers, available tech and scale – which means allocative decisions need to be made in advance.
Unfortunately, early evidence suggests a short-sighted self-interest on the part of a number of nations.
Past experience doesn’t bode well for co-operation either. The H1N1 pandemic of 2009, which killed 284,000 people, offers a salutary lesson. When a vaccine became available, virtually the entire global stock was bought up by a few developed countries. As Bollyky and Bown tell it, it was only after the World Health Organisation put out an appeal for donations that Australia, Canada, the US and six other countries agree to share 10% of their stocks – provided there were still sufficient supplies to meet all their own needs first.
Bollyky and Bown show how co-operation is the most efficient way to disrupt the virus – and they offer some lucid suggestions as to how this can be achieved.
For example, vaccine-manufacturing countries initially forgo immunisation of their entire populations so that non-producing countries can protect essential workers and vulnerable groups.
Other suggestions revolve around a framework agreement set up through an existing international forum, the need for a trade and investment agreement, and ensuring a mechanism of enforcement.
Of course, once these measures are in place, there’s the thorny issue of vaccine allocation at national level. That requires a decisive leadership, a capable state, solid health-care infrastructure, and fair and transparent decision-making.
Sadly, SA has fallen short on all of these counts.
*De Villiers is the features editor of the FM
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