The two big COVID-19 surges this year could be a preview of the future of the pandemic, with the coronavirus becoming more contagious, and some people getting infected multiple times a year, medical experts say.
“Intermittently getting COVID is going to be a way of life for the foreseeable future,” said Dr. Bruce Farber, chief of public health and epidemiology at Northwell Health.
Many experts had hoped there would be one major COVID-19 surge a year, in the late fall-winter period, that vaccines would protect most immunized people from getting infected, and that anyone who did get infected would usually be protected against reinfection for months.
That was before the rapid spread of omicron’s subvariants, which are genetic mutations of the original omicron strain. Omicron is more contagious than previous variants, and its subvariants are even more contagious.
What to know
- The two COVID-19 surges this year, separated only by several weeks, could be a preview of the future of the pandemic, medical experts say. Some people may get infected multiple times a year.
- The coronavirus is getting more contagious, and new subvariants of omicron are distinct enough that people can get infected with different subvariants within weeks.
- Experts say two subvariants now spreading in Europe and South Africa could lead to another spike in U.S. cases in the coming months. European health authorities say the BA.4 and BA.5 subvariants are very contagious.
The multiple waves of subvariants were unexpected, Farber said.
'The virus keeps surprising and twisting and turning in so many directions.'
- Dr. Bruce Farber, chief of public health and epidemiology at Northwell Health
Credit: Charles Eckert
“That’s not what anyone at all knew was going to happen,” he said. “The virus keeps surprising and twisting and turning in so many directions.”
Farber said it’s not surprising that the new subvariants are more easily transmissible than the original omicron. Their higher level of contagiousness allows them to “outcompete” earlier versions, he said.
Subvariants emerge because the coronavirus constantly replicates inside the body as it destroys cells, but those copies are not always exact, said Dr. Sharon Nachman, chief of pediatric infectious diseases at Stony Brook Medicine. When someone transmits the virus through, for example, a cough, that changed — or mutated — version of the virus may be passed on to another person, she said.
Only a tiny number of mutations are so significant that they eventually become subvariants, Nachman said. And some mutations never spread because, for example, the person carrying the mutation may be isolating or wearing a mask, which both prevent the spread to others, she said.
A totally different variant — such as omicron, which followed delta — involves more mutations than a subvariant, Nachman said.
From the beginning, omicron and its subvariants have had a key advantage over their predecessors: They are much more easily able to infect people who are vaccinated, who had recent COVID-19 infections, or both, said Sean Clouston, an associate professor of public health at Stony Brook University.
“What’s amazing is how fast COVID has been able to adapt and how fast it is now able to spread between individuals,” Clouston said.
COVID-19 has spread much more widely this May compared with the previous two springs. Long Island’s positivity rate has been above 10% for weeks. The positivity rate was below 1% in late May of last year.
This year, the new subvariants and the widespread shunning of masks, especially in schools, where kids are indoors together for hours, is causing a surge, Clouston said. Children then pass on the virus to adults, he said.
Nearly 6,000 students in Long Island schools tested positive in the two weeks ending Friday, six times the 981 who did so during the two weeks ending March 17, state data shows.
COVID-19 hospitalizations overall on Long Island nearly quadrupled over the past two months, from 125 on April 1 to 490 on Tuesday, falling to 445 by Thursday. More than half of those hospitalizations were of people admitted for reasons other than COVID-19, state data shows, although COVID-19 can exacerbate preexisting conditions.
Nachman said the large majority of COVID-19 patients at Stony Brook University Hospital are unvaccinated. Although omicron and its subvariants are more likely to cause infection in vaccinated people than previous variants, unvaccinated people are still twice as likely to test positive for COVID-19 as vaccinated people, and they’re many times more likely to be hospitalized or die, according to the U.S. Centers for Disease Control and Prevention.
New spikes seen overseas
Clouston and other experts are casting a wary eye at Portugal and South Africa, where the subvariants BA.4 and BA.5 are causing new spikes in cases.
The European Center for Disease Prevention and Control this month warned that those subvariants are adept at evading immunity from vaccination and previous infection and predicted that their high level of contagiousness means they may cause a major surge in cases throughout Europe in the coming months.
Clouston said BA.4 and BA.5 likely then will spread widely in the United States, where a small number of cases already have been reported.
“I would anticipate there will be a surge from that,” he said. “It’s unclear when that will happen.”
Farber said BA.4 and BA.5 could become dominant in the United States within the next few months.
“If that happens, we are going to continue to see for the time being what we’re seeing now, which is multiple infections that we thought people would have immunity to,” he said.
People are “getting reinfected with minor subvariants, but potentially even the same subvariant over and over again,” he said.
Dr. George Rutherford, an epidemiologist at the University of California, San Francisco, said immunity is stronger if the body encounters the same subvariant again, making reinfection less likely.
“The more they look alike, the more readily the immune system can recognize them,” he said.
Clearly, though, people infected with one subvariant can get reinfected with another shortly afterward, Clouston said.
'Even though you may think, ‘‘I just had this. I can’t get this again,’’ it’s probably not true.'
-Sean Clouston, associate professor of public health at Stony Brook University
Credit: Randee Daddona
Clouston said a relative got infected twice within six weeks, probably the first time with the original omicron variant and the second time with BA.2.
“Even though you may think, ‘I just had this. I can’t get this again,’ it’s probably not true,” he said.
“The reason these variants are able to infect a lot of people and travel across the globe is because they can infect people who have already been sick, or who have already been vaccinated,” Clouston added.
Reinfection rate rising
The more recently you were sick, or the more recently you were vaccinated or received a booster shot, the more likely you are to have some protection, Clouston said. But, as his relative’s repeated infections illustrate, it’s unclear how much, he said.
The delta variant, which was dominant for about six months until it was supplanted by omicron in December, led to few reinfections, Clouston said.
State health department data shows the rate of reinfections soared as omicron began dominating, and the rate has been steadily rising again since mid-March as the original omicron declined and subvariants took over. Between mid-December and May 22, there were more than 221,000 cases of New Yorkers getting reinfected with COVID-19. That number does not include people who tested themselves at home and didn't report results to authorities.
“We know prior infection offers some protection, but it’s not as good as with vaccines and boosters,” said Dr. Wafaa El-Sadr, a professor of epidemiology and medicine at the Mailman School of Public Health at Columbia University.
Nasal vaccines now being studied in clinical trials could potentially be more effective at decreasing the chance of infection, she said.
A big unknown is whether a variant will emerge that is more likely to cause severe illness and death and even better at evading the immune protection from the vaccine or previous infection, El-Sadr said. What is clear is that mask-wearing and avoiding large crowds are still effective ways to limit transmission and protect older adults and others who are at higher risk, she said.
“We need to focus on what we can do today,” she said. “What the virus can throw at us, we don’t know.”