A virus that shows no signs of disappearing, variants adept at evading the body’s defenses, and waves of infections two, maybe three times a year — this could be the future of Covid-19, some scientists now fear.
The central problem is that the coronavirus has become more adept at reinfecting people. Already, those infected with the first Omicron variant are reporting second infections with the 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 could even get a third or fourth infection within this year, researchers said in interviews. And a small fraction may have symptoms that last for months or years, a condition known as long-term Covid.
“It seems likely to me that that will be some sort of long-term pattern,” said Juliet Pulliam, an epidemiologist at Stellenbosch University in South Africa.
“The virus will continue to develop,” she added. “And there’s probably going to be a lot of people who get many, many reinfections over their lifetime.”
It is difficult to quantify how often people are re-infected, in part because many infections are now unreported. dr. Pulliam and her colleagues collected enough data in South Africa to say that Omicron’s speed is higher than previous variants.
This is not how it should have been. Earlier in the pandemic, experts thought that immunity to vaccination or previous infection would prevent most reinfections.
The Omicron variant crushed that hope. Unlike previous variants, Omicron and its many descendants appear to have evolved to partially evade immunity. That makes everyone — even those who have been vaccinated multiple times — vulnerable to multiple infections.
“If we manage it the way we manage it now, most people will get infected with it at least a few times a year,” said Kristian Andersen, a virologist at the Scripps Research Institute in San Diego. “I’d be surprised if it doesn’t go that way.”
The new variants have not changed the basic usefulness of the Covid vaccines. Most people who have received three or even two doses will not get sick enough to require medical care if they test positive for the coronavirus. And a booster dose, such as a previous bout with the virus, seems to reduce the chance of reinfection, but not by much.
At the start of the pandemic, many experts based their expectations of the coronavirus on the flu, the viral enemy they are most familiar with. They predicted that, as with the flu, there could be one major outbreak each year, most likely in the fall. The way to minimize its spread is to vaccinate people before they arrive.
Instead, the coronavirus behaves more like four of its closely related cousins, circulating year-round and causing the common cold. While studying common cold coronaviruses, “we saw people with multiple infections within a year,” said Jeffrey Shaman, an epidemiologist at Columbia University in New York.
If reinfection proves to be the norm, the coronavirus “will not be just this once a year in the winter,” he said, “and it won’t be a minor nuisance in terms of the amount of morbidity and mortality it causes.”
Reinfections with earlier variants, including Delta, occurred, but were relatively rare. But in September, the rate of reinfections in South Africa seemed to pick up and was remarkably high in November, when the Omicron variant was identified, said Dr. pulliam.
Reinfections in South Africa, as in the United States, may seem even more striking because so many have now been immunized or infected at least once.
“The perception magnifies what is actually going on biologically,” said Dr. pulliam. “There are just more people who are eligible for reinfection.”
The Omicron variant was so different from Delta, and Delta from previous versions of the virus, that some re-infections were to be expected. But now Omicron appears to be developing new forms that penetrate the immune defenses with relatively few changes in the genetic code.
“This is actually a bit of a surprise to me,” said Alex Sigal, a virologist at the Africa Health Research Institute. “I thought we would need some kind of brand new variant to escape this. But actually it seems like you don’t.”
An infection with Omicron causes a weaker immune response, which appears to decline rapidly compared to infections with previous variants. While the newer versions of the variant are closely related, they differ enough from an immune perspective that infection with one doesn’t offer much protection against the other — especially after three or four months.
Still, the good news is that most people reinfected with new versions of Omicron will not become seriously ill. At the moment, in any case, the virus has not found a way to completely bypass the immune system.
“That’s probably as good as it gets for now,” said Dr. signal. “The great danger could come when the variant becomes completely different.”
Any infection can carry the possibility of prolonged Covid, the constellation of symptoms that can last for months or years. It’s too early to know how often Omicron infection leads to long-term Covid, especially in vaccinated people.
To keep up with the evolving virus, other experts said, Covid vaccines need to be updated faster, even faster than flu vaccines every year. Even an imperfect match with a new strain of the coronavirus will still boost immunity and provide some protection, they said.
“Every time we think we’re through this, every time we think we’ve got the upper hand, the virus is fooling us,” said Dr. Andersen. “The way to get it under control is not, ‘Let’s all get infected a few times a year and then hope for the best’.”
