With a Covid-19 vaccine likely still many months away, there is debate about whether people who have had the illness and recovered have immunity and can escape the isolation the rest of us face.
In the United Kingdom these days, some are proposing that “immunity passports” could be provided to people who are found by testing to have the antibodies in their blood that might prevent them from getting reinfected and spreading the disease.
It’s an attractive idea on the surface. Many of the people infected are healthcare workers and they are urgently needed back at work. Would they need the same level of protection if they’ve already had the virus? Some see it as a way to restore the economy with recovered workers, even as most of the rest of the population remains in isolation.
But there are still too many unanswered questions about the nature of the immune response to Covid-19. And there are dozens of logistical questions.
How can people who have had the disease be accurately tested, not only to prove they have protective antibodies in their blood, but also to prove they are no longer contagious? How would certification occur to issue an “immunity passport”? Would people desperate to return to work cheat the system to acquire such a “passport”? Would there be an incentive for some people to get the disease deliberately?
- This article, “‘Immunity passports’ could speed up return to work after Covid-19” in The Guardian discusses the “passport” idea.
As the article points out, Germany is leading the way in testing for antibodies.
- This April 3 article on CNN, “Is an ‘immunity certificate’ the way to get out of the coronavirus lockdown?” also covers the issue well.
- This article in the Harvard Gazette, talks about a blood testing tool, VirScan, that tests for traces of antibodies from more than 1,000 strains of viruses and bacteria. The tool might help researchers learn more about immunity from Covid-19, as well as to learn more about how the disease spreads.
- Vox ran an April 2 article, “How Covid-19 immunity testing can help people get back to work,” which gives an overview of serological (blood) testing and its potential to allow people to return to work.
While health researchers tend to believe that the body develops a degree of immunity after Covid-19, it’s not yet understood how effective or long lasting it is.
And there are reports from China and elsewhere of people recovering from Covid-19 and then being reinfected. Experts debate whether this is the result of faulty testing, patients who continue to show signs of the old infection, or whether the disease doesn’t lead to sufficient immunity.
- This recent article in TIME discusses the reinfection issue.
It points out that tests after the disease may find residual viral RNA (Ribonucleic acid) that is not enough to cause the disease, but is enough to show up on tests.
For the record, here’s what the U.S. Centers for Disease Control and Prevention (CDC) has to say about reinfection in a longer FAQ (Q&A) in the Transmission section:
“Q: Can people who recover from COVID-19 be re-infected with SARS-CoV-2?
“A: The immune response, including duration of immunity, to SARS-CoV-2 infection is not yet understood. Patients with MERS-CoV are unlikely to be re-infected shortly after they recover, but it is not yet known whether similar immune protection will be observed for patients with COVID-19.”
In an ideal world, the virus would provide lifetime immunity, similar to what happened in my age cohort where many of us were infected by measles as children before a vaccine was developed in the 1960s. But immunity to respiratory diseases doesn’t normally last as long.
It could also work like the common cold, also caused by coronaviruses, where at best there is partial immunity for a few months, and at worst another of the many strains may cause another cold even sooner. But so far there’s nothing to suggest the virus is rapidly mutating.
Researchers, however, tend to look to previous spreads of SARS (2003) and MERS (2012-present) for clues on how Covid-19 may behave. Antibodies from SARS last for about three years according to studies, and MERS is believed to provide immunity for about a year.
- See this article in Asian Pacific Journal of Allergy and Immunology for a technical discussion of differences and similarities between SARS-CoV-1, the virus causing SARS; SARs-CoV-2, the virus causing Covid-19; and MERS-CoV, the virus causing MERS (Middle East Respiratory Syndrome).
- This article from NPR (U.S. National Public Radio) was gives a good overview on the question of whether immunity develops after Covid-19. This article was referenced in a previous OsoyoosPersists.ca story on a related subject, “We’re in this for the longer haul.”
Even assuming the best – that you can only get Covid-19 once and that immunity lasts long enough after getting it – there are still numerous public policy questions before an “immunity passport” system could be implemented, if it’s even desirable.
There’s ongoing pressure from some in business communities to return to business as usual before health experts say it’s safe. This pressure led to U.S. President Trump’s ludicrous suggestion that churches across his country should reopen to full congregations in time for Easter, on April 12.
After arguing for a while that the cure of isolation, shutdown and physical distancing, and its impact on the stock market was worse than the disease, (which, as of April 4, has killed more than 8,000 in the U.S.), Trump reversed himself.
A similarly misguided policy in the UK was promoted in early March when it was thought that by letting enough healthy people get infected early, the population would develop “herd immunity.” As a result, that country was slower to implement stricter physical distancing measures.
- See article in National Geographic, which suggests it might take 60 per cent of the population to be immune to Covid-19 for “herd immunity” to be reached – the point at which each infected person infects on average fewer than one new person.
The policy was quickly abandoned when new studies suggested it would overrun healthcare facilities – the opposite of “flattening the curve” – as even many young people are hospitalized.
Simulations by Imperial College London suggested the numbers could be staggering.
- This article, “What is herd immunity and could it prevent Covid-19?” on Healthline gives a clear explanation and argues that “herd immunity” – through people contracting the disease before there’s a vaccine – isn’t the answer.
“Once a vaccine is developed for this virus, establishing herd immunity is one way to help protect people in the community who are vulnerable or have low functioning immune systems,” writes Noreen Iftikhar, MD
- This opinion piece by Matt Gurney in the National Post argues the using “herd immunity” by exposing people to the disease rather than using self isolation and containment is a “dangerously wrong” policy.
Until there is a vaccine, we probably won’t develop the “herd immunity” sufficient to stop the disease, but the immunity of individuals may allow them to return to work without risk of infecting others. There are still too many unknowns, and we’re not there yet, but there is hope.