The omicron variant of the coronavirus, along with its subvariants, continues to be the dominant cause of Covid infections in the U.S. One subvariant, called BA.5, is behind the majority of new infections, but other omicron subvariants, and even subvariants of subvariants, are also being detected.
Although there are still uncertainties about the different versions of the omicron variant, experts have a clearer understanding about it and how it affects people who are vaccinated or unvaccinated or who have previously had cases of Covid.
What are the symptoms of omicron?
In August, the Food and Drug Administration authorized a new version of the Covid booster that targets the spike protein of both the BA.4 and BA.5 subvariants. This booster also targets the original strain of the virus that was first detected in Wuhan, China in late 2019.
For most people, at least those who are up to date on their Covid vaccinations, the original type of the omicron variant caused a milder illness that resembled the common cold, another form of the coronavirus.
Anecdotally, doctors say, the symptoms of the BA.4 and BA.5 subvariants are mostly similar to those of the earlier version of the variant.
“As far as we can tell, the BA.5 has not really proven too much different from the previous omicron waves,” said Dr. Bernard Camins, the medical director for infection prevention for the Mount Sinai Health System in New York. “We just know that it’s more contagious.”
Dr. Roy Gulick, the chief of infectious diseases at Weill Cornell Medicine and and NewYork-Presbyterian, said typical symptoms of the omicron subvariants include:
- Sore throat
- Hoarse voice
- Nasal congestion
- Runny nose
- Muscle aches
With the original version of the omicron variant, which swept across the U.S. at a dizzying speed last winter, the loss of taste and smell was not as common as with the earlier alpha and delta variants. However, with the spread of BA.4 and BA.5, that symptom seems to have returned, some doctors note.
While the omicron variant may have appeared milder during the winter Covid wave, that could have been a reflection of the groups who were getting sick: the young and otherwise healthy, as well as those who were fully vaccinated.
The Centers for Disease Control and Prevention recommends that all people ages 5 and up get an updated Covid booster shot to protect against waning immunity from the vaccines. People are eligible for a booster if they’ve received their full primary series and if it’s been at least two months since their last shot.
Because BA.5 is so contagious and it appears to dodge the body’s immune system, people are more vulnerable to reinfection with Covid, especially if it has been more than 90 days since the previous illness.
“Previous infection doesn’t guarantee protection anymore,” said Camins of Mount Sinai.
For the most part, reinfections are likely to be less severe than previous infections, thanks to higher levels of immunity, experts say.
Does omicron cause less severe illness?
There has been evidence that the omicron variant tends not to burrow deeply into the lungs as much as previous variants. A study, which was posted online by the University of Hong Kong and has not yet been peer-reviewed, found that while the omicron variant is less severe in the lungs, it can replicate faster higher up in the respiratory tract.
In that way, it may act more like bronchitis than pneumonia, said Dr. Hugh Cassiere, the director of critical care services for Sandra Atlas Bass Heart Hospital at North Shore University Hospital on Long Island, New York.
“Usually patients with acute bronchitis tend not to be short of breath. They tend to cough and produce sputum,” he said. “Patients with pneumonia tend to be short of breath and feel more fatigued than bronchitis in general.”
A small study from the CDC found that people who had Covid and are later reinfected with the omicron variant may experience fewer symptoms than they did during their initial bouts with the virus.
Still, it is virtually impossible for people to rely on symptoms to self-diagnose an illness. Doctors urge people who have any cold symptoms or flulike symptoms to get tested.
How quickly do omicron symptoms appear?
The time it takes for an infected person to develop symptoms after an exposure is shorter for the omicron variant than for previous variants — from a full week down to as little as three days or less, according to the CDC.
While much more research is needed, it makes scientific sense that a highly contagious virus like the omicron variant would have a shorter incubation period. Its goal, after all, is to infect as many people as possible as quickly as possible.
“That’s why the spread is occurring at a much faster pace,” said Dr. Anita Gupta, an anesthesiologist and critical care physician at the Johns Hopkins School of Medicine. She added that it is possible the incubation period could be shorter or longer depending on a number of variables, including age, underlying health problems and vaccination status. “There is no hard and fast rule here.”
“A lot of these patients are not having the symptoms for the 10 to 12 days that I saw when there were no vaccinations,” said Dr. Rahul Sharma, the emergency physician-in-chief at the NewYork-Presbyterian/Weill Cornell Medicine.
What is the duration of omicron symptoms?
Sharma noted that, in general, symptoms appear to be shorter and milder in the vaccinated compared to the unvaccinated.
For the vaccinated, emergency room or hospital stays are also typically shorter with the omicron variant.
“What I can tell you is that patients that are unvaccinated are definitely our sicker patients,” Sharma said. “Those are the patients that are more likely to go to the ICU. Those are the patients that are more likely to be admitted to the hospital.”
Dr. Ryan Maves, an infectious diseases and critical care physician at the Wake Forest School of Medicine in North Carolina, agreed, saying the overwhelming majority of Covid patients he sees in the intensive care unit are unvaccinated.
When should I get tested for Covid?
Given the potential for a shorter incubation period, Schaffner of Vanderbilt advised that anyone who has been in contact with an infected person get tested about 72 hours after the exposure.
“If you’ve been exposed and now you’re asking yourself, ‘When should I get tested?’ I think you would best wait at least three days to see if you’ve turned positive,” he said.
If you have a known exposure to someone with Covid, the CDC recommends to “get tested at least 5 days after exposure.”
Could omicron lead to long Covid?
Although much about the omicron variant remains unknown, some experts say it could lead to long Covid, even with mild cases. In a recent study, British researchers found that the omicron variant is less likely to cause long Covid symptoms than delta, although all of the 41,361 adult participants who regularly reported their Covid symptoms on a phone app had been vaccinated.
Patients with long-term symptoms can experience crushing fatigue, irregular heart rhythms and other issues months after their initial Covid infections. That occurred during the first wave of the pandemic, and it continued to lead to long Covid issues through the delta wave.
Previous research suggests that vaccination can greatly reduce the risk for long Covid.
How worried should I be about omicron?
The BA.5 omicron subvariant accounted for nearly 80% of new Covid cases as of Oct. 8, according to the CDC. Another subvairant, BA.4.6, accounts for just over 13% of sampled cases.
Because the BA.5 subvariant is so much more transmissible, people should probably “re-engage in some of the prevention strategies that we recommended earlier,” Gulick said. “So wearing masks indoors or wearing masks in crowded places is a reasonable thing to do.”
There is no data yet to suggest that BA.5 or other known omicron subvariants are “more aggressive viruses than the other ones,” Gulick said.
Because it is easier to catch than the other viruses, people really need to get vaccinated and boosted, he said.
“That’s the best protection we have.”