How often can you get the coronavirus?
The massive spread of the omicron variant has led scientists to conclude that we could be reinfected several times in the course of a few months.
A virus that shows no signs of disappearing, specialized variants to evade the body’s defenses and waves of infections two or even three times a year: that may be the future of COVID-19, some scientists fear.
The central problem is that the coronavirus has become more adept at reinfecting people. Those who got the first omicron variant are already reporting second infections with newer versions of the variant: BA.2 or BA2.12.1 in the United States, or BA.4 and BA.5 in South Africa.
Those people may suffer a third or fourth infection, even as early as this year, the researchers said in interviews. And a small fraction may have symptoms that will persist for months or years, a condition known as persistent covid.
“It seems likely to me that that will be a long-term pattern,” said Juliet Pulliam, an epidemiologist at the University of Stellenbosch in South Africa.
“The virus is going to continue to evolve,” he added. “And there will probably be many people who get many, many reinfections throughout their lives.”
It’s hard to quantify how often people get re-infected, in part because many infections go unreported. Pulliam and her colleagues have collected enough data in South Africa to say that the rate is higher with omicron compared to previous variants.
This is not how it was supposed to be. At the start of the pandemic, experts thought that immunity from vaccination or previous infection would prevent most reinfections.
The omicron variant shattered those hopes. Unlike previous variants, omicron and its various versions appear to have evolved to partially evade immunity. That leaves everyone, even those who have been vaccinated multiple times, vulnerable to multiple infections.
“If we continue to manage it with current methods, most people will get it at least a couple of times a year,” said Kristian Andersen, a virologist at the Scripps Research Institute in San Diego. “I would be very surprised if it doesn’t evolve that way.” Can You Get Covid Twice?
The new variants have not altered the fundamental usefulness of covid vaccines. Most people who have received three or even two doses will not get sick enough to need medical attention if they test positive for the coronavirus. And a booster dose, as well as prior infection with the virus, seems to decrease the chance of reinfection, but not by much.
At the start of the pandemic, many experts based their expectations about the coronavirus on influenza, the most familiar viral enemy to them. They predicted that, as with the flu, there could be a large outbreak each year, most likely in the fall. To minimize the spread, people should be vaccinated before that season.
However, the coronavirus is behaving more like its four closely related cousins that circulate and cause colds throughout the year. As we study common cold coronaviruses, “we saw people with multiple infections over the course of a year,” said Jeffrey Shaman, an epidemiologist at Columbia University in New York.
If reinfection becomes the norm, the coronavirus “is not going to be a phenomenon that only happens once a year during the winter,” he said, “and it is not going to be a mild nuisance in terms of the amount of morbidity and mortality that causes”.
Although reinfections with the above variants, including delta, did occur, they were rare. But in September, the pace of reinfections in South Africa appeared to pick up and was remarkably high in November, when the omicron variant was identified, Pulliam said.
Reinfections in South Africa, like in the United States, may seem even more conspicuous because many people have already been vaccinated or have been infected at least once.
“Perception magnifies what is actually going on biologically,” Pulliam said. “What happens is that there are more people who are eligible for reinfection.”
The omicron variant was sufficiently different from the delta, and delta was also different from previous versions of the virus, so some reinfections were expected. But now, omicron appears to be developing new forms that penetrate immune defenses with relatively few changes to their genetic code.
“This is a bit of a surprise to me,” said Alex Sigal, a virologist at the Africa Health Research Institute. “I thought we would need a completely new variant to escape this one. But in fact, it seems that it is not so.
An infection with omicron produces a weaker immune response, which appears to wane rapidly, compared to infection with earlier variants. Although the newer versions of the variant are closely related, from an immunological perspective, they vary enough that infection with one does not provide much protection against the others, and certainly not after three or four months.
Despite that, the good news is that most people who are reinfected with new versions of omicron will not become seriously ill. At least for now, the virus hasn’t found a way to completely evade the immune system.
“That’s probably the best we have for now,” Sigal said. “The big danger could arise when the variant is completely different.”
Each contagion can bring the possibility of a persistent covid, a constellation of symptoms that can persist for months or years. It is too early to know how often an omicron infection leads to a persistent covid case, especially among vaccinated people.
According to other experts, in order to keep up with the evolution of the virus, covid vaccines must be updated more quickly, in shorter periods than annual flu vaccines. Even an imperfect match with a new form of coronavirus will broaden immunity and offer some protection, the specialists said.
“Every time we think we’re through this, every time we think we have an advantage, the virus fools us,” Andersen said. “The way to control it is not to say, ‘We’re going to get infected a few times a year and then hope for the best.'”
Apoorva Mandavilli is a reporter for the Times, focusing on science and global health. In 2019 she won the Victor Cohn Award for Excellence in Medical Science Reporting.
