COVID has been a disastrous and deadly illness for millions of people, but as a virus, it’s been highly successful.

And the key to its success – mutations that make it easier for the virus to find new hosts – is likely to continue for some time, scientists say.

“Its mutations have been somewhat unpredictable,” compared to other viruses, said Dr. James Jarvis, physician leader of Incident Command at Northern Light Health. “The major shifts have come far quicker.”

That explains why the coronavirus has grown to a global pandemic, rather than an outbreak limited to a small geographic area that only lasted a few months. The coronavirus, in relatively short order, became a worldwide illness that is now entering its third year of spreading around the globe, with Maine experiencing yet another wave of infections and hospitalizations.

On Friday, two new highly contagious strains of the virus, omicron BA.4 and BA.5, were detected in Minnesota. Those subvariants fueled a surge of cases in South Africa despite high levels of immunity there, and experts are watching to see if they spread around the globe and drive surges elsewhere. There have been no reports of it being detected in the Northeast.

While the newer variants are better at infecting people who have previous immunity, vaccines have continued to protect against severe illness and hospitalization, officials say.

In one way, Jarvis said, COVID resembles other respiratory viruses: Its mutations have made it more transmissible and easier to catch while the symptoms have become milder.

But, he said, COVID stands out because of how quickly and easily it spreads. And it can still be deadly. Older people who have underlying medical conditions are still likely to get very ill if they catch the virus.

Genetic mutations that create different variants are a natural process for viruses, said Lori D. Banks, who teaches biology at Bates College and specializes in infectious disease and molecular virology.

“It’s just a function of how they replicate,” Banks said.

A virus’ replication is similar to how humans perpetuate or drop certain attributes, she said. For instance, a child may strongly resemble his or her parents, but that child’s children are likely to resemble them less.

VIRUSES MUTATE TO FIND NEW HOSTS

Viruses also can retain or discard certain attributes, she said, especially if it makes it easier to find a new host. The faster they spread and replicate, the more opportunities for troublesome mutations.

“The outside of the virus particle is what your immune system is reacting to,” she said, but it’s also the part that changes most quickly as the virus replicates. “And something changes a little bit every time it replicates.”

It’s impossible to predict what will change in the virus as it mutates, Banks said, but scientists and labs work overtime to try to determine what characteristics are different when a new variant of COVID emerges.

Public health officials are aware of the urgency of spotting new variants quickly, said Dr. Ashish Jha, the White House COVID-19 Response Coordinator.

“We’ve got to continue being on the lookout for new variants, new subvariants (and) continue to do that surveillance,” Jha said during a White House briefing Wednesday.

Those variants are the reason the pandemic is still rolling more than two years after it emerged. The last few months, Jha said, show how those variants are making it difficult to get the pandemic under control.

“We were hit with the BA.1 wave of infections in December (and) January. We saw BA.2, and now we’re seeing, in a large chunk of the country, BA.2.12.1,” he said. “They are more contagious with more immune escape and they are driving a lot of the increases in infection that we’re seeing across the country right now. And that is a huge challenge.”

BA.2.12.1 is the variant causing a lot of the infections in Maine and New England this spring, and is expected to spread across the country in coming weeks. Its virulence is the reason that the federal Centers for Disease Control and Prevention said last week that local authorities might want to consider again imposing mask mandates, particularly for public indoor spaces, where they’ve been dropped.

VACCINES STILL BEST PROTECTION

While the mutations have resulted in new strains that tend to cause less severe symptoms, they also have made it more likely for people to be infected even after they have already had the disease or been vaccinated. The newest subvariants are better able to infect people who have waning levels of immunity, which is why many Americans are advised to get booster doses four months after their last dose of vaccine.

The virus is likely to have the ability to continue building on its success at mutating, said Dr. Nirav Shah, head of the Maine Center for Disease Control and Prevention. That means anyone hoping the pandemic will end soon is likely to be disappointed.

“The fact that it has been circulating widely for more than two years provides opportunities to mutate as humans with the virus transmit it to other humans,” Shah said in an email Friday. “COVID-19 virus adapts in similar ways to other common viruses. Viruses need hosts, so they mutate in ways that ensure that they will continue to have available hosts.”

Although some variants seem to be less affected by vaccines and natural immunities, it’s still important for people to get vaccinated and boosted, Shah said.

“Data show that being vaccinated and boosted greatly reduces the risk of hospitalization or death with any known COVID variant,” he said. “The protection was strongest for the original strain and a bit less with the current strain, which is why the booster doses of the vaccine are so important – to provide the added protection needed as the virus changed.

“There is a possibility we’ll get a new vaccine at some point that is based on the newer variants,” Shah said. “For right now, though, we still have COVID in our communities and we need to protect ourselves and the best way to protect yourself today is with the vaccines that we have right now.”

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