True or false: you can't get Covid-19 once you have had it?
Given that Covid-19 is a new disease, there's much that we don’t know about it.
Some of the world's governments have reported that they’ve picked up antibodies in people who have recovered from the disease. Based on the assumption that they'd be protected against reinfection, they've suggested issuing these people with an “immunity passport” that would enable them to travel or return to work.
To get to the bottom of whether this would be feasible, we asked a trio of medical experts the following question: “Is it true that once you’ve had Covid-19 you’re immune to it?”
Here's what they had to say:
PROF KEERTAN DHEDA
Director of the Lung Infection and Immunity Unit and head of Pulmonology at the University of Cape Town and Groote Schuur Hospital
We are not sure if people develop long-term immunity once they get Covid‑19. This virus has only been with us for a few months and we will only know about immunity after conducting long-term studies.
In laboratory experiments, those who have had Covid‑19 can generate antibody responses that seem to be protective (we call these neutralising antibodies), but whether this will carry through in real life, and for how long people may be immune, is unclear.
With some infections, like measles for example, once you get them, you rarely get them again. Whereas with others, like tetanus, one often does not develop immunity. When it comes to those like influenza, immunity does not develop because the structure of the viruses that cause them changes from year to year.
SARS-CoV-2 [the virus that causes Covid-19] is only one of five coronaviruses affecting humans — the other four cause common colds in adults and we don’t seem to develop good long-term immunity to any of them. Whether it will be the same for Covid‑19 remains unclear. Only time will tell.
PROF LYNN MORRIS
Interim executive director of the National Institute for Communicable Diseases (NICD)
Unfortunately there is insufficient information to inform this critical question.
Covid-19 is likely to become endemic and occur annually, like seasonal influenzaProf Lynn Morris of the NICD
Immunity relies on the ability of the human body to develop specific antiviral responses, including neutralising antibodies. Such antibodies generally develop following viral infection (and vaccination) and provide protection from reinfection.
Since Covid-19 is a new disease, there has not been an opportunity to study this. This is important to understand because Covid-19 is likely to become endemic and occur annually, like seasonal influenza.
DR KGOSI LETLAPE
President of the Health Professions Council of South Africa (HPCSA)
The expectation from an infection disorder that you have survived would be that you would have mounted a response to it and fended it off. The human response would be the development of antibodies.
What is envisaged is that those who have recovered from Covid-19 will be tested to see whether they have antibodies against the coronavirus and, if so, whether those antibodies are protective and for how long.
What is clearly being demonstrated, however, is that some people who have had Covid-19 ... have become reinfected. This means the antibodies were not protective — or that even though they’d had the infection, they didn’t develop a good enough immune response to protect them [from it] in the future.
In terms of Covid-19, it’s still new. There are people that have antibodies and ... whose [blood] serum has been used to treat patients [to] good effect ... but not everybody that has antibodies is necessarily protected against future infection.