What Are the Symptoms of the New COVID Strain?

Current COVID strains, all descendants of the Omicron lineage, tend to cause symptoms centered in the upper respiratory tract: sore throat, runny nose, congestion, cough, headache, and fatigue. Fever remains common, though high fevers are less typical than they were in earlier waves. The shift away from the deep-lung infections that defined the original pandemic years reflects real biological changes in how the virus enters cells. But the symptom picture is not identical for everyone, and a few specifics are worth knowing if you are trying to figure out whether that scratchy throat is COVID or something else.

The Core Symptom List

If you catch a current COVID strain, the symptoms you are most likely to notice overlap heavily with a bad cold or mild flu. Sore throat, cough, nasal congestion, and a runny nose are the hallmarks. Fatigue and headache are also extremely common. Fever shows up in a large share of cases, and body aches or muscle pain are reported frequently. Loss of smell and taste, which was almost a signature of earlier variants, has become much less prominent with Omicron-lineage strains. It still occurs, but far fewer people experience it than during 2020 or 2021.

Gastrointestinal symptoms have been part of the COVID picture from the start. Diarrhea affects roughly one in ten to one in five patients across various studies.¹ Nausea, vomiting, and abdominal pain also show up, though less consistently. These gut symptoms can appear alongside respiratory ones or, occasionally, as the only noticeable signs of infection.

Why Newer Strains Hit the Throat More Than the Lungs

The reason current strains feel more like a head cold than the pneumonia-like illness of 2020 has a biological explanation. Earlier variants, especially Delta, relied heavily on a specific enzyme on lung cells to break into those cells. Omicron and its descendants have shifted toward an alternative entry route that works well in the upper airways but less efficiently in deep lung tissue.² Specific mutations on the virus’s spike protein drive this change, reducing the virus’s ability to fuse with cells in the lower respiratory tract while making it more adept at infecting the nose, throat, and upper airways.³

This is not just a laboratory observation. Clinical data from both children and adults confirms that Omicron-era infections produce symptoms concentrated in the upper airways, with fewer cases progressing to the kind of lower-lung involvement that filled hospitals in previous waves.⁴ That said, severe lower-respiratory disease has not disappeared entirely, and rare but dangerous presentations like epiglottitis (swelling of the tissue that covers the windpipe) have been flagged in case reports during Omicron surges.⁴

Symptoms Come On Faster Than They Used To

One practical difference with current strains is speed. You get sick sooner after exposure. A meta-analysis of incubation periods across variants found that the original strain averaged about six and a half days from exposure to first symptoms, while Omicron brought that down to roughly three and a half days.⁵ A separate systematic review confirmed the trend: Omicron BA.1 had a pooled incubation period of about three and a half days, the shortest of any variant studied.⁶

This matters for your daily life. If someone in your household tests positive, you are more likely to develop symptoms within two to four days rather than the nearly week-long wait that was common in 2020. The flip side is that the window between getting exposed and becoming contagious is also shorter, which is part of why these strains spread so efficiently.

How Your Immune History Shapes What You Feel

The symptoms you experience are not determined solely by the virus. Your immune background plays a large role. People who have been both vaccinated and previously infected tend to report fewer symptoms during a new infection compared to those with no prior exposure.⁷ In one study of healthcare workers, people with this combined immunity reported a median of three symptoms, while those without prior infection reported four. Booster vaccination independently reduced symptom counts as well.⁷

This helps explain why so many people now describe COVID as “just a cold.” For someone with several rounds of vaccination and a past infection, the immune system recognizes the virus quickly and limits how far the infection progresses. But for someone encountering the virus with less immune preparation, the same strain can still produce a genuinely miserable week of fever, aches, and exhaustion. Pre-existing immunity does not guarantee you will avoid symptoms altogether; it tends to make the illness shorter and milder.⁸

Symptoms in Children

Fever is the single most common symptom of COVID in children, regardless of variant. A large study of over 2,000 children in Beijing during an Omicron wave found that about 95% developed fever, with temperatures ranging up to 40°C (104°F).⁹ Cough was next most common, followed by sore throat, nasal congestion, and runny nose. Fatigue, headache, and muscle or joint pain were also frequently reported.⁹

One age-specific wrinkle worth flagging: very young children, particularly those under five, developed sore throat and hoarseness more often during the Omicron era compared to earlier variants. Some of these cases involved croup, a barking cough caused by swelling around the vocal cords.¹⁰ If your toddler develops a distinctive seal-bark cough during a COVID surge, this is likely why. The broader pattern for children mirrors adults: symptoms are heavily concentrated in the upper airways, and serious lung involvement is uncommon.

Symptoms That Look Different in Older Adults

Older adults can present with COVID in ways that do not look like a respiratory infection at all. A scoping review found that roughly three in ten older adults with COVID showed atypical presentations, meaning their primary symptoms were not cough, fever, and sore throat.¹¹ Delirium, meaning sudden confusion or altered mental state, was the most common atypical sign, with prevalence in studies ranging from about 9% to 67%.¹¹ Loss of appetite was another frequent finding, and falls were reported across multiple studies as well.

The mortality rate among older adults with atypical presentations was strikingly high, roughly 28% across the studies reviewed.¹¹ The danger is that these patients, or the people caring for them, may not think to test for COVID because the symptoms do not match the expected pattern. If an elderly person becomes suddenly confused, stops eating, or starts falling without an obvious cause, COVID should be on the list of possibilities, especially during periods of high community transmission.

Rapid Tests Work Best a Few Days In

A frustrating reality of current COVID infections is that rapid antigen tests are not very reliable on the first day of symptoms. Research on testing sensitivity found that rapid tests picked up only about 30% to 60% of true infections on symptom day one. By day three, sensitivity climbed to roughly 59% to 75%, and by day four it reached about 80% to 93%.¹²

The explanation is timing. With newer variants, viral loads peak slightly later relative to when symptoms first appear than they did with earlier strains. So you might feel terrible on day one, test negative, and assume it is not COVID, when in fact you just tested too early. If that first test is negative and your symptoms persist or worsen, testing again on day three or four gives you a much more accurate answer. This gap between symptom onset and peak viral shedding also means you can be contagious before a rapid test catches it.

A Lot of Infections Produce No Symptoms at All

Not everyone who catches COVID knows it. Asymptomatic infection has been a feature of every variant, but the rate varies. A study comparing different variant surges through airport screening found that during an Omicron surge, over 6% of travelers tested positive, far higher than the rates during Beta or Delta waves.¹³ Many of these positive travelers had no symptoms. The high transmissibility of Omicron-lineage strains combined with broad population immunity means a large pool of people are walking around with active infections and no idea they are spreading the virus.

This is worth keeping in mind if you are trying to protect a vulnerable household member. The person who brings COVID home may never develop a single symptom themselves.

Long COVID After Omicron Strains

The acute illness is one thing. The lingering aftermath is another. Long COVID, generally defined as symptoms persisting beyond three months, still occurs after Omicron infections, though at lower rates than after earlier variants. One study found that over 10% of people infected with an Omicron strain were still symptomatic at three months, compared to about 37% in a pre-Omicron group. At six months, the figures were 9% and 28%, respectively.¹⁴ Certain symptoms that were hallmarks of early long COVID, especially hair loss and smell disorders, became less common in the Omicron era.¹⁴

The profile of long COVID symptoms may also be shifting. Recent research suggests that cardiopulmonary long COVID symptoms, such as persistent shortness of breath and chest tightness, have become less common with newer variants.¹⁵ Meanwhile, neurological complaints like brain fog, poor concentration, and fatigue remain persistent problems across all variant eras.¹⁶ Risk factors for developing long COVID after an Omicron infection include hospitalization, older age, and certain underlying conditions like emphysema, asthma, and autoimmune diseases. Vaccination was protective, reducing the odds.¹⁴

An interesting wrinkle: one study found that patients infected with Omicron actually reported higher scores for general, respiratory, and gastrointestinal symptoms at the one-month follow-up compared to patients who had been infected with pre-Omicron variants.¹⁷ The authors adjusted for prior immunity levels, which may partly explain the counterintuitive finding. At longer time points, the Omicron group generally fared better, but the one-month data is a reminder that “milder acute illness” does not automatically mean “milder aftermath.”

Antiviral Treatment and Symptom Rebound

If you test positive and start Paxlovid, the most commonly prescribed antiviral for COVID, there is a reasonable chance your symptoms will resolve faster. In a controlled trial during an Omicron wave, patients treated with Paxlovid had their first symptoms resolve in about five days, compared to about seven and a half days with standard care.¹⁸ Paxlovid-treated patients also had a lower rate of lingering post-COVID symptoms.¹⁸

The trade-off that gets attention is symptom rebound. Some people feel better after finishing a five-day Paxlovid course, then get worse again. Rebound of COVID symptoms within seven days of treatment happened in roughly 2% to 4% of patients in a large study, and about 5% to 6% within 30 days.¹⁹ Rebound was not unique to Paxlovid; another antiviral, molnupiravir, showed similar rates. People who experienced rebound tended to have more underlying medical conditions.¹⁹ So if you finish an antiviral course and your symptoms return a few days later, you are not imagining it, but the phenomenon is not as common as early headlines suggested.

Telling COVID Apart From Other Respiratory Infections

At an individual level, you really cannot distinguish COVID from flu or RSV based on symptoms alone. The overlap in sore throat, cough, fever, fatigue, and congestion is too great. Loss of smell or taste, when it occurs, is still more suggestive of COVID than of other common viruses, and early symptom-tracking models identified it as the strongest single predictor of a positive test.²⁰ But with newer variants causing this symptom less often, even that clue has become less reliable.

The host’s genetic background also influences how symptoms manifest. Variations in immune-system components that help recognize viruses and launch an early response can affect whether an infection stays mild or progresses to something more serious. These same kinds of genetic differences shape how people respond to flu and RSV, which is one reason the same virus can cause barely noticeable sniffles in one person and a week in bed for another.²¹

Self-reported symptom tracking through apps proved useful earlier in the pandemic for identifying emerging symptom patterns and building screening tools.²² That infrastructure has largely wound down, but the practical lesson remains: testing is the only reliable way to know. If the answer matters, whether because of a vulnerable contact, upcoming travel, or access to antivirals, a rapid test on day three or four of symptoms is your best bet for an accurate result.

1
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