One in four cases may be going undetected with symptoms other than cough or fever

Concern that people with loss of taste or smell failed to self-isolate as they did not realise they had virus

CORONAVIRUS may be going undetected in one in four people with symptoms because they exhibit signs of the virus other than a persistent cough or high temperature, ministers have been warned.

Scientists on the New and Emerging Respiratory Virus Threats Advisory Group (Nervtag), which has been helping to shape the Government’s response to Covid-19, expressed concern that individuals with only lesserknown symptoms, such as a loss of taste or smell, may not be self-isolating and receiving tests for the disease. The Department of Health has said it is keeping public guidance on symptoms under review.

Peter Openshaw, a professor of experimental medicine at Imperial College London, who sits on Nervtag, said it was important that patients and doctors had a “wider perception” of how coronavirus can present itself.

He also pointed out that the swab test typically used to establish whether a patient has Covid-19 may be less likely to detect infection in cases where the disease is primarily causing symptoms elsewhere in the body, such as the digestive system, rather than the nose and lungs.

Official guidance describes “new continuous cough and/or high temperature” as the “most common symptoms”, and states that those with such symptoms should stay at home for seven days.

But Flusurvey, a system run by Public Health England using data from more than 8,000 people, shows a greater number of people reporting a loss of smell than those stating that they have a combination of a fever and a cough.

At a Nervtag meeting on March 13, the day after Boris Johnson first instructed those with a cough or high temperature to stay at home, scientists raised concerns that “individuals with the virus may not meet the definition”.

According to minutes of the meeting, John Edmunds, professor of infectious disease modelling at the London School of Hygiene & Tropical Medicine, “raised an issue with the new case definition for the current self-isolation guidelines”.

The minutes said: “There was concern that the phraseology might mean that a number of individuals with the virus may not meet the definition.

“John Edmunds was working off a recent paper that could mean that one in four cases could be missed if the criteria of only a cough and/or fever are used and this is if there was 100 per cent compliance to the current definition, which is unlikely”.

The minutes note that one study had identified fatigue and muscle ache as two other “main symptoms” and the panel agreed to monitor whether “the case definition is fit for purpose”.

Prof Openshaw said: “In the selfreported symptoms, the loss of sense of smell comes out as a very, very frequent one.

“But in terms of how often that would actually lead to a diagnosis of Covid, that’s not quite clear.”

He added: “So at the moment, there’s not necessarily a strong case for expanding beyond the fever and cough when it comes to self-isolation – those are still those are still very prominent and important presenting symptoms – but I think we are over time appreciating that it’s a much more diffuse disease presenting in many different ways.

“It is important people have a wider perception of how it may present.

“The original, very restrictive definition, I think, was not picking up a lot of people who actually might have Covid.”

Prof Openshaw confirmed that one in four cases could still “easily” be missed as a result of the focus on coughing and high temperatures.

Officials maintain that they used the best available data to establish the most likely symptoms, before anyone with a new cough or fever was first asked to isolate, in March.

But the UK’s position was at odds with France, where people with loss of taste and smell were being advised to consider self-isolating even if they lack the main two symptoms.

On March 26, it emerged that Chris Whitty, the Chief Medical Officer, was considering designating taste and smell deprivation a symptom of coronavirus, as the World Health Organisation said it was checking the link.

But last month, Jonathan Van-Tam, his deputy, said: “There is some anecdotal data that there is a proportion of people who do indeed lose their sense of taste and smell. However, whether that on its own is a symptom [of the virus], the answer from our experts is absolutely not.”

A Department of Health spokesman said: “We continue to keep symptoms under expert scientific review as we strengthen our understanding of the virus.

“The symptoms selected were those that captured those most likely to have Covid-19, while not capturing a great number of people who did not.”