Updated on January 10, 2022.
The Omicron COVID variant, which was first identified in South Africa, has quickly spread around the world. The first U.S. case was announced December 1, and it outcompeted Delta as the dominant strain, accounting for most new COVID cases just a few weeks later. As of January 1, it accounted for more than 95 percent of all new infections in the United States.
Scientists are still racing to understand more about Omicron, including its severity, how easily it spreads and how well it may evade existing vaccines and antiviral treatments.
Meanwhile, nearly three years into the pandemic, about 62 percent of the U.S. population is fully vaccinated and roughly 35 percent has gotten a COVID booster. Despite a surge of new cases across the country, many Americans are more anxious than ever to get back to “normal.”
Will Omicron derail efforts to bring the pandemic to an end? Why are experts more worried about this particular variant? Will existing vaccines protect against it?
Here is what we know so far.
Why Omicron is raising alarms
On November 26, Omicron joined Alpha, Beta, Gamma and Delta on the World Health Organization’s list of variants of concern. Scientists are working quickly to determine if this new variant spreads more easily, causes more severe disease and if it it’s less susceptible to existing COVID vaccines and antiviral treatments.
Why? It has worrisome mutations—a lot of them.
Viruses’ genetic material mutates all the time as they replicate in an infected person. Most coronavirus mutations are actually harmful to the virus or have no effect either way. But mutations that make the virus more effective are likelier to persist and spread.
A good example of this is the highly contagious Delta variant, which was the dominant strain in the United States from the summer to fall 2021 and accounted for nearly all new COVID-19 cases during that time.
Research suggests that the Delta variant is at least twice as infectious as initial COVID strains but Omicron is about 10 times as contagious. The newer variant outcompeted Delta to become the dominant strain in a matter of weeks.
“We are dealing with a highly, highly transmissible variant that spreads rapidly. The data are overwhelming in that regard,” Dr. Fauci said in a White House press briefing.
Omicron contains a large number of mutations—more than any other COVID variant. These mutations include more than 30 changes to the spike protein that the coronavirus uses to infect cells. (The spike protein is also the target of existing COVID vaccines.) Some of these mutations were also found on Delta and are associated with greater infectiousness and less susceptibility to antibodies.
“Omicron evades immune vaccine protection against symptomatic disease and, to some extent, to severe disease,” Fauci said.
Does this mean the vaccines won’t work?
The COVID vaccines available in the United States are still highly effective in preventing severe disease. Data compiled over the past two years is clear: the COVID vaccines help keep people alive and out of the hospital. Researchers estimate that in the U.S. alone, they’ve saved 279,000 lives.
The vaccines are also helping to slow the spread of the disease, helping to ease the burden on an overwhelmed healthcare system and avoid closures and shutdowns. They also help reduce the odds that more variants will emerge.
The efficacy of the vaccines, however, has waned over time, which is why U.S. health officials are urging all those eligible to get a booster, which has been shown to bolster protection against Omicron.
One study published December 23 in Cell found that three doses of an mRNA vaccine lead to potent antibodies to Omicron, while only two did not work as well to fight off the variant.
Meanwhile, Pfizer-BioNTech and Moderna aren’t taking a “wait and see” approach to Omicron or the possibility of more variants. The drug makers are testing their COVID vaccines against Omicron.
Pfizer is reportedly working to adapt its mRNA vaccine within six weeks and could ship initial batches “within 100 days in the event of an escape variant.”
Moderna also announced that it’s already testing a higher dose booster (100 µg) in healthy adults. The company notes it is studying two booster candidates designed to anticipate mutations, including those identified in the Omicron variant.
What you can do to protect yourself
The best way to protect yourself from severe infection is to get vaccinated. President Biden is urging Americans to get their shots. And those who are fully vaccinated should get a booster as soon as they are eligible.
All adults who received two doses of either the Pfizer or Moderna vaccines should get a booster five months after their second shot. The same is true for children and teens between 12 and 17 who got two Pfizer doses. Kids in this age group should get a Pfizer booster five months after their second shot.
Everyone who is moderately to severely immunocompromised and who is aged 5 years or older should get a third primary shot, 28 days after their second dose. Those who are aged 5 to 17 should get Pfizer. For those 18 and older, either Pfizer or Moderna is acceptable. For people who are moderately to severely immunocompromised and got J&J, no additional primary dose is recommended at this time.
As for boosters for moderately to severely immunocompromised people, those who received either Pfizer or Moderna should receive their booster 5 months after their third primary dose. (Only those aged 12 and older are eligible for a booster, whether or not they are immunocompromised.) Those who received J&J should get their booster 2 months after their shot.
And all adults who got the Johnson & Johnson (J&J) COVID vaccine are eligible for a booster at least two months later. Anyone getting a booster can choose to receive the same vaccine they got initially or they can “mix and match” and get one of the other COVID vaccines available for use in the United States. The CDC advises, however, that the Pfizer or Moderna boosters are preferred over J&J in most situations.
The fact remains, even if Omicron renders existing vaccines less effective, immunization is still the best way to protect against severe disease.
“Current data demonstrate that receiving a booster dose is critical to provide protection against COVID-19 and the Omicron variant,” said Dr. Rochelle Walensky in the White House press briefing. “Please, get vaccinated. Get your kids vaccinated. And if you’re eligible for a booster, get a booster shot.”
As the pandemic wears on, people should rely on the other proven strategies used to protect against COVID-19: wearing masks, distancing, and washing their hands well and often.
Ensuring that all nations have access to a vaccine is critical to slowing the spread of the COVID-19 and bringing the pandemic to an end. Until enough people around the world are vaccinated, the coronavirus will continue to circulate and mutate, potentially evolving more ways to resist immunity.
