Omicron: the symptoms and key differences from a cold

New Covid variant can easily be mistaken for an everyday illness

Coronavirus vaccination
(Image credit: Leon Neal/WPA Pool/Getty Images)

A growing body of evidence that Omicron causes cold-like symptoms has prompted calls for an urgent update of government guidance on spotting the Covid-19 variant.

According to data from the ZOE Covid study, which tracks reports of symptoms uploaded to an app by the public, the new “rapidly spreading” strain is producing “mild” symptoms that are “very hard” to differentiate from a common cold without testing, The Independent reported.

Tim Spector, who founded the ZOE project, said the data suggests that about half of all Omicron cases were being “missed” because they are not presenting with “classic” Covid symptoms of fever, new and persistent cough and a loss or change of smell or taste.

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“It is going to be producing cold-like symptoms that people won’t recognise as Covid if they just believe the official government advice,” Spector, a professor of epidemiology at King’s College London, told the BBC’s Breakfast programme.

New symptoms

Early reports from South Africa, where Omicron was first detected, suggest that symptoms “in the country's fourth wave are far milder than in previous waves”, said The Guardian.

Although case rates “surged by 255%” within a week in early December as the new strain spread, “there is mounting anecdotal evidence that infections with the Omicron variant are provoking milder symptoms”, the paper reported.

However, England’s Chief Medical Officer Chris Whitty has urged caution over the information emerging from South Africa. Whitty told a Downing Street press conference earlier this week that “the amount of immunity in South Africa for this wave – because of a prior Delta wave and vaccination – is far higher than it was for their last wave”.

“That doesn’t mean that there isn’t some degree of slightly milder disease, that is possible,” he added. “But I just think there’s a danger people have over-interpreted this to say, this is not a problem and what are we worrying about?

According to Zoe study founder Spector, the “majority of symptoms” linked to Omicron are identical to those of a severe winter cold. Omicron symptoms include headaches, sore throat, runny or stuffy nose, fatigue, sneezing and coughing.

John Bell, regius professor of medicine at Oxford University, told BBC Radio 4’s Today programme that myalgia, a form of muscle pain, appeared to be another “distinguishing feature” of infection with the coronavirus variant.

A “bit of gut upset”, including “loose stools”, was also a symptom of the new strain, which is “behaving differently” from previous Covid variants and is “very, very infectious”, Bell said.

Vaccine protection

Research is ongoing into the level of protection that existing vaccines provide against Omicron. In a positive development, researchers in Israel found that a three-shot course of the Pfizer vaccine provided a significant defence against the new Omicron variant.

Gili Regev-Yochay, director of the Infectious Diseases Unit at the Sheba Medical Center, told Reuters that a booster dose of the Pfizer jab increased protection “about a hundred fold”.

According to Washington D.C.-based news site NPR, US researchers have reported that preliminary results suggest three doses of the Moderna vaccine are also “effective” against Omicron. “Scientists are doing similar experiments testing the Johnson and Johnson vaccine alone, as well as the J&J vaccine with a Pfizer booster,” the site continued.

However, the news about the “power of vaccines” is “mixed”, with initial research suggesting that level of infection-fighting antibodies in people who have had only two doses of a Covid vaccine are not high enough to ward off Omicron.

But on another positive note, the chief executive of the London-based Royal Society for Public Health (RSPH), Christina Marriott, has reported that “growing evidence shows that people who’ve received two doses of the vaccine typically present with less severe symptoms” than those who have not been jabbed.

She added: “It’s important for people who’ve been fully vaccinated to stay vigilant for cold-like symptoms and get tested if they’re living or working around people who are at greater risk from the disease.”​

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