One of the most vexing questions about the coronavirus pandemic is this: can you catch the virus more than once? A lot of people are hoping for one and done! Then there is the question: can the virus come back and cause a relapse? There are stories on the web that some people have been reinfected by COVID-19. They seemingly get over it, only to get sick again. If this were the case, we might never achieve herd immunity, even with a vaccine.
The Swedish Controversy:
Swedish researchers reject the idea that people can be reinfected by COVID-19. Dr. Anders Tegnell is Sweden’s chief epidemiologist. He has taken a lot of flak for the high death rate in Sweden compared to other Scandinavian countries. In fact, Sweden has one of the highest death rates in the world, ahead of the U.S., Brazil and Mexico.
Prominent scientists from Swedish universities and research institutes criticized public health authorities and the government this week. Sweden did not close factories, offices, restaurants or bars the way other European countries did. The experts tell their colleagues around the world:
“In Sweden, the strategy has led to death, grief and suffering and on top of that there are no indications that the Swedish economy has fared better than in many other countries. At the moment, we have set an example for the rest of the world on how not to deal with a deadly infectious disease.”
“In the end, this too shall pass and life will eventually return to normal. New medical treatments will come and improve the prognosis. Hopefully there will be a vaccine. Stick it out until then. And don’t do it the Swedish way.”
Sweden is very far from developing herd immunity. It is estimated that less than 10% of the population has antibodies to the coronavirus. That is not even close to the level that is needed to achieve protection so the virus will die out.
Is There Any Good News From Sweden?
But Dr. Tegnell has defended his strategy. At a press conference this week he stated that:
“We don’t see cases of people falling ill twice from Covid-19.”
Dr. Tegnell suggests that people who have contracted and recovered from COVID-19 seem to have immunity that lasts at least six months. Even people who don’t have high levels of antibodies appear to have T-cell mediated protection:
“The risk of being reinfected and of transmitting the disease to other people is probably very close to zero. Therefore, we think that you can meet other people, even if they are in a high-risk group.”
Other Experts Agree: People Are Unlikely to Become Reinfected by COVID-19:
Dr. Angela Rasmussen is an expert in virology at Columbia University in New York City. She is quoted in the New York Times (July 22, 2020) as saying:
“I would say reinfection is possible, though not likely, and I’d think it would be rare. But even rare occurrences might seem alarmingly frequent when a huge number of people have been infected.”
Vaccines and Herd Immunity:
The hope is that once a large number of people are vaccinated the world will develop herd immunity. That means that the virus will gradually disappear, since most people will be able to avoid getting sick and won’t transmit the disease to others.
That is why the Swedish data on immunity look so promising. Even if antibody levels drop to undetectable levels, T-cell immunity could prevent people from being reinfected by COVID-19. We hope this optimistic perspective holds up once there are more data and once the vaccines become widely available.