A new subvariant of Omicron is set to become the dominant variant of COVID-19 in the U.S. soon. BA.2.12.1 is currently responsible for 42.6% of COVID-19 cases in the country, according to data from the Centers for Disease Control and Prevention (CDC). That’s a big increase from the 7.5% of cases it was responsible for in early April.
This is a subvariant that public health officials are keeping an eye on—and trying to learn more about. “Additional evaluation is currently underway to understand the impact of BA.2.12.1 on vaccine effectiveness,” CDC Director Rochelle Walensky said in a press briefing late last month. “But importantly, we continue to believe that those who are vaccinated and especially those who are boosted, continue to have strong protection against severe disease, even from BA.2.12.1.”
The rise of BA.2.12.1 comes not long after the end of most mask mandates across the country—including on public transportation. With that, you probably have some questions about what this variant is and how concerned you should be. Here’s what you need to know.
What is BA.2.12.1?
BA.2.12.1 is a subvariant of the Omicron variant BA.2, aka “stealth Omicron,” explains William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine. “You can think of it as a son or daughter of Omicron,” he says. “They’re really very similar.”
But BA.2.12.1 has gotten plenty of attention for how contagious it is. “It is the most transmissible form of SARS-CoV-2 described,” says Amesh A. Adalja, M.D., a senior scholar at the Johns Hopkins Center for Health Security. (SARS-CoV-2, in case you’re not familiar with it, is the virus that causes COVID-19.)
BA.2.12.1 has certain mutations in its spike protein that cause it to be more infectious, Dr. Schaffner says.
Why is BA.2.12.1 rising in the U.S.?
There are a few different reasons for the rise of BA.2.12.1 in the U.S., according to Thomas Russo, M.D., professor and chief of infectious disease at the University at Buffalo in New York. One is how infectious it is, he says.
“The original Omicron—BA.1—was more infectious than previous variants,” Dr. Russo explains. “BA.2 was felt to be about 30% more infectious than BA.1 and BA.2.12.1 is thought to be 30% more infectious than BA.2.”
The fast spread of BA.2.12.1 also coincides with loosened restrictions just about everywhere, Dr. Russo says. “Both of those really are what is driving its spread,” he says.
There’s also the simple fact that BA.2.12.1 is beating out other variants to make people sick, Dr. Adalja says. “It is rising by simple Darwinian principles—it transmits more efficiently and is outcompeting other SARS-CoV-2 lineages,” he says.
What are the symptoms of BA.2.12.1?
Doctors and public health officials are still learning more about BA.2.12.1 but, as of now, Dr. Schaffner says that it’s believed to cause the same symptoms as other forms of COVID-19. Those include, per the CDC:
- Fever or chills
- Shortness of breath or difficulty breathing
- Muscle or body aches
- New loss of taste or smell
- Sore throat
- Congestion or runny nose
- Nausea or vomiting
“It does not appear to be more serious than other forms of COVID-19,” Dr. Schaffner says. “And, very importantly, our vaccines according to lab studies appear to provide pretty good coverage against this subvariant—but you have to get the third dose.”
How worried do I need to be about BA.2.12.1?
Dr. Adalja says that the rise of BA.2.12.1 is “completely expected,” adding, “the virus will continue to evolve to become more and more transmissible.” Meaning more highly infectious variants are expected to follow.
While this variant should be a concern for everyone, Dr. Russo says that people who should be the most concerned are those who are considered high risk for serious complications for COVID-19.
“Get your booster shot, if you’re eligible,” Dr. Russo says. “And if you’re considered high risk, be careful. Few people are wearing face masks right now. You should consider masking up to protect yourself while we have a large community burden of disease.”
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