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Two subvariants of Omicron—BA.2 and BA.2.12.1—are currently dominating COVID-19 case porn counts in the U.S. But despite being more than two years into the coronavirus pandemic, there's still some confusion as to what having COVID-19 looks like from start to finish, especially as new variants and subvariants continue to pop up.
Generally speaking, Omicron and its subvariants cause more mild disease than previous variants like Delta—but that doesn't mean it's completely harmless for everyone. Some people, particularly those who are unvaccinated, are still at risk for severe disease, hospitalization, or even death. Breakthrough infections, too, are expected to occur with Omicron and its subvariants.
And while the Omicron may be somewhat milder, its subvariants have gotten increasingly more contagious: BA.2, which began its rise in late-February and early-March, was estimated to be about 30%–60% more transmissible than its predecessor, BA.1. And now, BA.2.12.1—the new dominant Omicron subvariant in the U.S.—is thought to be about 25% more transmissible than that.
Omicron and its iterations likely aren't going away anytime soon, and you may still contract the virus (although likely a milder version) even if you've been vaccinated, boosted, or have had a previous case of COVID-19. In that case, here's what a typical timeline of an Omicron infection looks like, from exposure to immunity.
Incubation Period and Testing
Omicron and its subvariants have shorter incubation periods, which means it takes less time for symptoms to appear after exposure to the virus.
"Omicron has the shortest incubation period that we've seen," infectious disease expert Amesh Adalja, MD, a senior scholar at the Johns Hopkins University Center for Health Security, told Health. That incubation period is just about three days, compared to the Delta variant's five-day incubation period, and the original SARS-CoV-2 virus' incubation period of more than 5 days.
According to Dr. Adalja, Omicron's short incubation period may be influenced by built-up immunity from the past two years. Much of the population has been exposed to COVID-19 at one point or another—via vaccination or prior infection—which means their immune systems are already primed to jump into action more rapidly. How soon symptoms occur is directly tied to when your immune system recognizes and responds to the virus, said Dr. Adalja.
The shortened incubation period also means that people may test positive sooner, due to emerging symptoms. According to guidelines from the Centers for Disease Control and Prevention, you should test as soon as you begin feeling any cold- or flu-like symptoms. If you test negative but continue to feel ill, you can test again one to two days later, or talk to a health care provider about taking a PCR test, which is typically more sensitive. If you've been exposed to COVID-19 but don't develop symptoms, the CDC suggests testing five days after exposure.
CDC Study Says Omicron Variant's Incubation Period Is About 3 Days—Here's What That Means
Symptom Onset
Because of Omicron's shortened incubation period, those who are infected will begin to show symptoms sooner, if they're symptomatic. Most of the time, particularly because Omicron tends to be less severe, a case may look a lot like the common cold, or even allergies.
"As your body starts recognizing the fact that it's been infected, your immune system will start taking actions, and those actions are those symptoms that you feel: fatigue, headache, malaise," said Dr. Adalja. People may not test positive during these initial symptoms, simply because there isn't enough virus in the body to show up on a test (though there is enough to make you feel unwell), he said.
Though symptoms of Omicron aren't drastically different from those associated with the Delta variant, they are manifesting differently, Pia MacDonald, PhD, MPH, an infectious disease epidemiologist at RTI International, told Health. The most commonly-reported symptoms with the original Omicron variant were cough, fatigue, congestion, and runny nose. Research published in The Lancet also found that sore throat and hoarse voice were consistently more prevalent with Omicron infections than with Delta.
Meanwhile, loss of taste and smell, which was a common symptom with previous variants, is less likely to occur with Omicron. And while some reports say gastrointestinal symptoms are also more common with Omicron than previous variants, evidence suggests GI issues were just as prevalent with Alpha and Delta.
One thing that can drastically reduce symptom severity in people with Omicron is prior vaccination and booster doses. "This is a huge difference among vaccinated versus unvaccinated [people] in terms of severity of disease for an infected person," said MacDonald. "Even with the newer Omicron variants, being vaccinated and boosted is very protective for severe infection, hospitalization, and death."
As far as how long these Omicron symptoms last, research shows that people have acute symptoms for about six to seven days—about two days shorter than Delta's eight to nine days of acute illness. That said, length of symptoms varies greatly depending on the person, their vaccination status, the severity of disease, and any risk factors. "In general, the fact that Omicron is occurring in a highly-immune population should diminish the symptoms because the virus is able to clear faster," said Dr. Adalja.
Despite these often less severe symptoms and potentially reduced symptom duration, it's still essential for those who are at high risk of severe illness from COVID-19 to check in with a health care provider if they contract the virus. This way, they can potentially get a prescription for Paxlovid, an antiviral medication used to help prevent severe illness from the disease. While some people have reported 'Paxlovid rebound'—or a recurrence of COVID-19 symptoms after they've finished their course of treatment—those rebound symptoms tend to be mild and only last a few days.
Generally speaking, Omicron and its subvariants cause more mild disease than previous variants like Delta—but that doesn't mean it's completely harmless for everyone. Some people, particularly those who are unvaccinated, are still at risk for severe disease, hospitalization, or even death. Breakthrough infections, too, are expected to occur with Omicron and its subvariants.
And while the Omicron may be somewhat milder, its subvariants have gotten increasingly more contagious: BA.2, which began its rise in late-February and early-March, was estimated to be about 30%–60% more transmissible than its predecessor, BA.1. And now, BA.2.12.1—the new dominant Omicron subvariant in the U.S.—is thought to be about 25% more transmissible than that.
Omicron and its iterations likely aren't going away anytime soon, and you may still contract the virus (although likely a milder version) even if you've been vaccinated, boosted, or have had a previous case of COVID-19. In that case, here's what a typical timeline of an Omicron infection looks like, from exposure to immunity.
Incubation Period and Testing
Omicron and its subvariants have shorter incubation periods, which means it takes less time for symptoms to appear after exposure to the virus.
"Omicron has the shortest incubation period that we've seen," infectious disease expert Amesh Adalja, MD, a senior scholar at the Johns Hopkins University Center for Health Security, told Health. That incubation period is just about three days, compared to the Delta variant's five-day incubation period, and the original SARS-CoV-2 virus' incubation period of more than 5 days.
According to Dr. Adalja, Omicron's short incubation period may be influenced by built-up immunity from the past two years. Much of the population has been exposed to COVID-19 at one point or another—via vaccination or prior infection—which means their immune systems are already primed to jump into action more rapidly. How soon symptoms occur is directly tied to when your immune system recognizes and responds to the virus, said Dr. Adalja.
The shortened incubation period also means that people may test positive sooner, due to emerging symptoms. According to guidelines from the Centers for Disease Control and Prevention, you should test as soon as you begin feeling any cold- or flu-like symptoms. If you test negative but continue to feel ill, you can test again one to two days later, or talk to a health care provider about taking a PCR test, which is typically more sensitive. If you've been exposed to COVID-19 but don't develop symptoms, the CDC suggests testing five days after exposure.
CDC Study Says Omicron Variant's Incubation Period Is About 3 Days—Here's What That Means
Symptom Onset
Because of Omicron's shortened incubation period, those who are infected will begin to show symptoms sooner, if they're symptomatic. Most of the time, particularly because Omicron tends to be less severe, a case may look a lot like the common cold, or even allergies.
"As your body starts recognizing the fact that it's been infected, your immune system will start taking actions, and those actions are those symptoms that you feel: fatigue, headache, malaise," said Dr. Adalja. People may not test positive during these initial symptoms, simply because there isn't enough virus in the body to show up on a test (though there is enough to make you feel unwell), he said.
Though symptoms of Omicron aren't drastically different from those associated with the Delta variant, they are manifesting differently, Pia MacDonald, PhD, MPH, an infectious disease epidemiologist at RTI International, told Health. The most commonly-reported symptoms with the original Omicron variant were cough, fatigue, congestion, and runny nose. Research published in The Lancet also found that sore throat and hoarse voice were consistently more prevalent with Omicron infections than with Delta.
Meanwhile, loss of taste and smell, which was a common symptom with previous variants, is less likely to occur with Omicron. And while some reports say gastrointestinal symptoms are also more common with Omicron than previous variants, evidence suggests GI issues were just as prevalent with Alpha and Delta.
One thing that can drastically reduce symptom severity in people with Omicron is prior vaccination and booster doses. "This is a huge difference among vaccinated versus unvaccinated [people] in terms of severity of disease for an infected person," said MacDonald. "Even with the newer Omicron variants, being vaccinated and boosted is very protective for severe infection, hospitalization, and death."
As far as how long these Omicron symptoms last, research shows that people have acute symptoms for about six to seven days—about two days shorter than Delta's eight to nine days of acute illness. That said, length of symptoms varies greatly depending on the person, their vaccination status, the severity of disease, and any risk factors. "In general, the fact that Omicron is occurring in a highly-immune population should diminish the symptoms because the virus is able to clear faster," said Dr. Adalja.
Despite these often less severe symptoms and potentially reduced symptom duration, it's still essential for those who are at high risk of severe illness from COVID-19 to check in with a health care provider if they contract the virus. This way, they can potentially get a prescription for Paxlovid, an antiviral medication used to help prevent severe illness from the disease. While some people have reported 'Paxlovid rebound'—or a recurrence of COVID-19 symptoms after they've finished their course of treatment—those rebound symptoms tend to be mild and only last a few days.
