THERE could be more than 400 active cases of coronavirus in Herefordshire, a coronavirus symptom study shows.

The heatmap shows an estimated 402 people in the county are currently infected with coronavirus.

Created by the Covid Symptom Study, an app which tracks people with the infection across the UK, the heatmap shows there are 3,421 contributors in the county.

Hereford Times:

Across the UK, 288,579 people are currently predicted to have symptomatic coronavirus, as of 5am on October 8.

Officials figures from Public Health England show that 1,072 people had been confirmed as testing positive for Covid-19 by 9am on Thursday (October 8) in Herefordshire, up from 1,060 the same time on Wednesday – but this is the number of all cases since March.

Since the same time last week, there has been 48 people test positive for Covid-19 in Herefordshire.

The findings from the app come as a separate study suggests the vast majority of people who test positive for coronavirus do not have any key symptoms on the day of their test.

Some 77 per cent of people who had a positive test had no symptoms on the day of their test, while 86 per cent did not have a cough, temperature or loss of taste or smell.

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Researchers led by Professor Irene Petersen at University College London (UCL) analysed data from the Office for National Statistics (ONS) coronavirus infection survey, which has been testing thousands of households every week regardless of whether people have symptoms.

The analysis looked at data for 36,061 people who had a test between the end of April and the end of June.

Some 115 (0.32 per cent) had a positive test result, the study found, of whom 27 (23.5 per cent) were symptomatic and 88 (76.5 per cent) were asymptomatic on the day of the test.

When looking at cough, fever and loss of taste/smell – seen as the three main symptoms – 86.1 per cent of those who tested positive had none of these.

Prof Petersen said people may have had symptoms in the days before their test or developed them later, but the figures suggested large numbers may be spreading the virus while asymptomatic.

She told the PA news agency: "They may be silent transmitters and they don't know about it. And so I think that's a problem.

"You may have a lot of people who are out in the society and they're not self-isolating because they didn't know that they are positive."

The researchers said there was a need to change testing strategies.

"Covid-19 symptoms are a poor marker of (Covid) infection," they wrote in the journal Clinical Epidemiology.

"In order to capture 'silent' transmission and potentially prevent future outbreaks, test programmes should involve frequent and widespread (Covid-19) testing of all individuals, not just symptomatic cases, at least in high-risk settings or specific locations."

Prof Petersen added: "Future testing programmes should involve frequent testing of a wider group of individuals, not just symptomatic cases, especially in high-risk settings or places where many people work or live close together such as meat factories or university halls."

Tim Spector, professor of genetic epidemiology at King's College London, who leads the Covid Symptom Study (CSS) app, said data from more than four million people who used the app and reported symptoms over a week found that 85 per cent of adults reported fever, cough or loss of taste/smell.

"But the data on children and the over-65s from the CSS app tell us a different story," he added.

"Only using the UK's three classic symptoms will miss around 50 per cent of cases in these important groups that were included in the ONS survey.

"In a sub-study at King's College London of twins using antibody testing and the ability to report 20 different symptoms, we showed that only 19 per cent of people are truly asymptomatic.

"We need to learn from other countries and improve awareness of all the symptoms of Covid-19 to properly control the spread of the virus."

Main picture: DronePics.Wales