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Omicron Infection Timeline: When Symptoms Start and How Long They Last

    In the United States, two Omicron subvariants, BA.2 and BA.2.12.1, are currently dominating COVID-19 case counts. Despite the fact that the coronavirus pandemic has been underway for more than two years, there is still some disagreement about what it means to have COVID-19 from start to finish, especially when new variations and subvariants emerge.

    In general, Omicron and its subvariants produce less severe sickness than prior variants such as Delta—but it doesn’t mean they’re fully risk-free. Some people, especially those who have not been vaccinated, are nevertheless at risk for serious illness, hospitalisation, and even death. Omicron and its subvariants are also likely to cause breakthrough infections.

    While the Omicron is milder, its subvariants have become extremely contagious: BA.2, which first appeared in late February and early March, was assessed to be 30–60 percent more transmissible than its predecessor, BA.1. BA.2.12.1, the new prevalent Omicron subvariant in the United States, is currently considered to be roughly 25% more transmissible.

    Omicron and its variants are unlikely to go away anytime soon, and even if you’ve been vaccinated, boosted, or had a previous case of COVID-19, you could develop the virus (albeit in a weaker form). In that case, here’s how an Omicron infection often progresses from exposure to immunity.

    Incubation Period and Testing

    The incubation periods of Omicron and its subvariants are shorter, which means symptoms occur sooner following exposure to the virus.

    Infectious disease expert Amesh Adalja, MD, a senior scholar at the Johns Hopkins University Center for Health Security, told Health, “Omicron has the shortest incubation period that we’ve encountered.” In comparison to the Delta variant’s five-day incubation period and the original SARS-CoV-2 virus’s incubation duration of more than five days, this incubation period is just about three days.

    Omicron’s short incubation period, according to Dr. Adalja, could be due to built-up immunity during the previous two years. COVID-19 has been exposed to a large portion of the population at some point, either by vaccination or prior infection, which means their immune systems are already primed to respond more quickly. According to Dr. Adalja, how quickly symptoms appear is directly related to how quickly your immune system recognises and responds to the infection.

    Because of the shorter incubation period, people may test positive sooner when symptoms emerge. According to the Centers for Disease Control and Prevention, you should get tested as soon as you start to feel cold or flu-like symptoms. If you test negative but still feel sick, you can repeat the test one to two days later or ask your doctor about a PCR test, which is usually more sensitive. The CDC recommends testing five days after exposure if you’ve been exposed to COVID-19 but haven’t developed symptoms.

    Onset of Symptoms

    Because of the shorter incubation time of Omicron, those who are infected will show symptoms sooner, if they are symptomatic. A case of Omicron may resemble a typical cold or even allergies most of the time, especially because it is less severe.

    “As your body recognises that it has been infected, your immune system will begin to take steps, and those actions are the symptoms you experience: weariness, headache, and malaise,” Dr. Adalja explained. People may not test positive during the early stages of symptoms because there isn’t enough virus in the body to show up on a test (but there is enough to make you sick), he explained.

    Although the symptoms of Omicron are similar to those of the Delta variation, they manifest differently, according to Pia MacDonald, PhD, MPH, an infectious disease epidemiologist at RTI International. Cough, weariness, congestion, and a runny nose were the most commonly reported complaints with the original Omicron variant. Sore throat and hoarse voice were also shown to be more common with Omicron infections than with Delta infections, according to a study published in The Lancet.

    Meanwhile, taste and smell loss, which was a common symptom of previous variations, is less prevalent with Omicron. While some sources claim that Omicron had greater gastrointestinal symptoms than prior versions, research reveals that GI troubles were just as common in Alpha and Delta.

    Prior immunisation and booster doses are one thing that can dramatically lessen symptom intensity in patients with Omicron. “In terms of the severity of disease for an infected person, there is a tremendous difference between vaccinated and unvaccinated [people],” MacDonald said. “Being vaccinated and boosted is substantially protective against serious illness, hospitalisation, and death, even with the newer Omicron strains.”

    When it comes to the duration of Omicron symptoms, research shows that patients have acute symptoms for six to seven days, which is two days less than Delta’s eight to nine days of acute illness. However, the duration of symptoms varies widely depending on the individual, immunisation status, disease severity, and any risk factors. “In general, the fact that Omicron occurs in a highly immune population should reduce symptoms because the virus may clear faster,” Dr. Adalja explained.

    Despite the fact that the symptoms are generally less severe and the symptom duration may be shorter, persons who are at high risk of serious sickness from COVID-19 should still see a doctor if they get the virus. This way, they might be able to acquire a prescription for Paxlovid, an antiviral drug that can help them avoid getting sick from the condition. While some people have had ‘Paxlovid rebound,’ or a recurrence of COVID-19 symptoms after finishing their therapy, these symptoms are usually moderate and typically last a few days.

    Isolating With Omicron

    The CDC has some very strict rules regarding COVID-19 isolation time, regardless of variant (for the time being): Regardless of immunisation status, you should isolate at home for five days if you test positive or display symptoms.

    It’s around this period when persons are most contagious and have the largest virus load. “The usual peak will be two days after it was found by a test,” MacDonald added.

    People may begin to ease off on isolating after five days. “Your likelihood, your risk of infecting people is drastically lowering after five days of either being found on a fast test or after symptom onset,” MacDonald added. That’s not to suggest there’s no risk, but the chances of it spreading are slim to none, she noted.

    You can cease your isolation after five days if you are asymptomatic for your disease, but you must continue to mask around others for another five days. If you acquire symptoms, you can cease your seclusion after five days (and continue to mask for another five days) if your symptoms are improving and you haven’t had a fever in the previous 24 hours.

    The CDC recommends isolation for at least 10 days and maybe up to 20 days for patients who have developed severe COVID-19 sickness or have a damaged immune system. According to MacDonald, infectiousness reduces significantly more quickly in immunocompetent patients. Immunocompromised individuals may have a more difficult time eradicating the infection and hence remain contagious for longer.

    Though the CDC does not encourage testing outside of isolation, it does say that if you have access to an at-home test, testing at the conclusion of the initial five-day period is the recommended method. If it results in a positive test, you should isolate until day 10.

    After Omicron, Immunity

    It’s crucial to remember that Omicron and its subvariants are still fresh COVID-19 iterations, so there’s not a lot of information on how much immunity is provided after infection. Experts in the field of medicine, on the other hand, offer some suggestions.

    “If you got infected with any of the variants of Omicron, there’s definitely good cross-protection of BA.1 and BA.2—and maybe less so with BA.4 and BA.5—but it’s unlikely that you’ll get [re]infected for a couple of months to several months after infection,” Dr. Adalja said.

    Vaccination appears to be a major element in determining how much immunity one can gain from an Omicron infection. An Omicron breakthrough infection—which occurs when a previously vaccinated and/or boosted individual contracts Omicron—improves immunity, according to new study published in the journal Nature. However, in uninfected people, Omicron infection may not provide any protection against non-Omicron forms.

    Overall, experts believe that immunity gained through vaccination is more durable than immunity gained through previous infection alone—and that vaccination and boosters provide the best protection—which means it’s critical “not to rely on natural immunity to be highly protective for Omicron,” according to MacDonald.

    Even if you have some immunity—whether from an Omicron infection alone or from an Omicron infection plus prior vaccination—still it’s crucial to keep an eye on your community’s risk level and follow CDC guidelines. While people can choose to wear a mask at any moment, it is nevertheless recommended that persons in high-transmission zones stay attentive and wear a mask indoors in public.