Experts monitor the data as new strains emerge.
[Originally published: Dec. 2, 2021. Updated: Dec. 9, 2022]
Note: Information in this article was accurate at the time of original publication. Because information about COVID-19 changes rapidly, we encourage you to visit the websites of the Centers for Disease Control & Prevention (CDC), World Health Organization (WHO), and your state and local government for the latest information.
COVID-19 moved at a rapid pace after Omicron surfaced in the United States toward the end of 2021 and spread like wildfire. Since then, multiple Omicron subvariants have emerged—two subvariants, BQ.1 and BQ.1.1 became the dominant strains in the U.S. in mid-November 2022, overtaking BA.5, which was thought to be a relatively mild version of the virus. The BQ strains are thought to be better than BA.5 at evading immunity from vaccination or previous infection.
By December, cases were rising again as people gathered for the holidays with family and friends—this year with fewer people wearing masks and taking other mitigation measures. Experts are still trying to better understand BQ.1 and BQ.1.1, while also monitoring more than 300 other descendants of Omicron around the world.
Omicron: A ‘variant of concern’ with potentially different symptoms
First, some background. Omicron was initially identified in Botswana and South Africa in November 2021—although later reports showed earlier cases in the Netherlands. On December 1, the CDC confirmed the first case in the U.S., in an individual in California who had returned from South Africa in November. Omicron was the predominant strain in the U.S. by late December. As people around the world welcomed a new year, the variant continued to surge more quickly than any previous strain in many areas. Both the WHO and the CDC classified it as a "variant of concern."
Early reports from South Africa indicated that most cases were mild—and that symptoms for this variant seemed to be different. “The reports show that patients in South Africa—many of whom were young—have had severe fatigue, but no loss of taste or smell,” says Lauren Ferrante, MD, a Yale Medicine pulmonologist.
But some people infected with Omicron still developed severe disease and had to go to the hospital, and some died. For that reason, experts continued to express concerns that a large volume of cases in a particular area could overwhelm medical centers, making it difficult to treat severe cases.
Are Omicron and its strains more transmissible—or deadlier—than previous variants?
From the beginning, two important questions about Omicron were top of mind for scientists, says Dr. Murray. As new variants have emerged, the first question has been how transmissible each one is compared to its predecessor.
According to the CDC, the Omicron variant spreads more easily than the original SARS-CoV-2 virus and the Delta variant. In its early days, the variant caused an alarming spike in COVID-19 cases in South Africa—they went from 300 a day in mid-November 2021 to 3,000 a day at the end of that month. In the first months of 2022, an Omicron subvariant called BA.2 began to spread even faster than other Omicron subvariants, followed by BA.4 and BA.5, only to be outdone by the BQ subvariants.
The second question has been whether Omicron and its subvariants are more likely than their predecessors to cause severe disease. While there is more to learn about BQ.1 and B.Q.1.1, experts are hoping prior immunity will be of some help. The original Omicron caused a record number of cases, but while it has also caused its share of hospitalizations and deaths, factors such as lengths of hospital stays, ICU admittance, and death were “lower than during previous pandemic peaks,” according to a CDC report in January 2022.
The CDC says the presence of severity of symptoms can be affected by vaccination, history of prior infection, and age and other health conditions.
Do current vaccines and treatments protect against severe disease from Omicron?
The Food and Drug Administration (FDA) has authorized bivalent vaccine booster shots from Pfizer-BioNTech and Moderna for most people ages 6 months and older. Bivalent means the shot protects against two strains of a virus, and these COVID-19 boosters are designed to protect against both the original SARS-CoV-2 virus and the Omicron variant. It is available to people two months after they’ve completed the two-dose primary series or received a previous booster dose.
Novavax also offers a booster shot, but it protects against the original SARS CoV-2 virus and may not protect against recent Omicron subvariants. The company says it expects to have a vaccine that will protect against the recent Omicron subvariants in 2023.
Paxlovid is still prioritized by the National Institutes of Health (NIH) for treatment of Covid-19. But in December, the FDA withdrew its authorization for the monoclonal antibody bebtelovimab, which proved to be ineffective against the BQ subvariants. Two months earlier, the FDA also updated its guidance on Evusheld, the only option for pre-exposure prophylaxis for people who are immunocompromised, to say that it may not protect against all variants.
When they first started to study Omicron, scientists were concerned about a key distinguishing factor in the variant. Unlike Delta and other coronavirus variants, it carries an abundance of mutations—about 50 in all, including 26 that are unique to the variant—and more than 30 on the spike protein, which is the viral protein that vaccines train the immune system to recognize and attack. Grubaugh said some of Omicron’s enhanced transmissibility could come from its ability to evade some immune responses, especially in people who were previously infected, but not vaccinated.
Scientists also wanted to know if these mutations indicated a possible reduction in the effectiveness of the COVID-19 vaccines and certain monoclonal antibody treatments. “We don’t really know how the mutations work together. Not everything is additive,” Grubaugh had said.
Will Omicron be the last variant?
People need to understand that variants like Omicron are a natural part of the progression of the virus, Grubaugh says.
New variants aren’t surprising, he says. While the BQ strains now make up the majority of cases, lesser known Omicron subvariants are also circulating in the U.S., including BF.7, BA.4.6, BN.1, and XBB, and no one can predict how they might evolve—or if they will simply vanish at some point. “Delta was never going to be the last variant—and Omicron is not going to be the last one," Grubaugh says. "As long as there is a COVID-19 outbreak somewhere in the world, there is going to be something new that emerges.”