This week, the Centers for Disease Control and Prevention announced that there’s a new top dog among COVID-19 variants in the United States: a subvariant known as omicron BA.2.
It’s closely related to BA.1 omicron, which caused the most recent surge in infections, but BA.2 may be a little bit more transmissible.
Both subvariants were present last November when the World Health Organization first identified omicron as a variant of concern. It’s unclear why BA.1 spread globally first and why BA.2 is now catching up.
Marcel Curlin, an associate professor of medicine at Oregon Health & Science University, said the BA.1 subvariant may have gained some random, early advantage. For instance, it may have been first to reach a global transportation hub like London, allowing it to spread efficiently.
Now BA.2 — with its apparent advantage in transmitting between people — has gained the edge.
The BA.2 subvariant is now responsible for more than half of COVID-19 cases in the United States, and state-level surveillance shows it is responsible for a growing percentage of cases in Oregon.
All of this, though, is happening against the backdrop of a global decline in cases.
Experts think while BA.2 will outcompete the other omicron variants, it’s unlikely to cause a big spike in cases while doing it.
“Most people, including myself, don’t think that’s going to happen,” said Curlin. “It’s not going to fuel a large spike in new cases like the original omicron wave.”
One key reason for that optimistic forecast: early research suggests that the BA.2 variant is relatively unlikely to re-infect people who’ve had its close relative, BA.1.
Curlin said the BA.2 variant is causing problems in places like Hong Kong, where much of the population still hasn’t been exposed to COVID-19 and a lower percentage of people have had an effective vaccine and booster shot.
By contrast, in the U.S., most people have either contracted the virus, gotten vaccinated, or both, which will likely dampen any potential new wave.
Still, Curlin said there are some early signs in wastewater monitoring data that COVID-19 infection levels are rising a little.
Older adults and people with factors like obesity and immunosuppression are at elevated risk from the virus when community transmission goes up, and should prioritize getting their booster shots.
The CDC recently recommended an additional booster for people 50 and older.
Curlin said the same public health messages about staying healthy during the pandemic remain true. A majority of people may experience milder symptoms, but an infection can be serious and even fatal. You can reduce your risk by masking in crowded indoor spaces.
People should weigh their own health and the people around them who are vulnerable — children too young to be vaccinated, for example.
“We’re in an era of personal judgment and responsibility,” he said.
COVID-19 hospitalizations in Oregon are just 10% of the peak they reached in February, and case numbers are near the lowest point they’ve reached since the pandemic began.
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