Coronavirus, Community testing and diagnosis

Have you had COVID-19 without knowing? (King’s College)

New study reveals at least one in five people infected don't show any symptoms

London and the South East of England

Community not hospital

Antibody testing on blood samples from 432 adults

12% (51) of those tested were positive for COVID antibodies

19% (9) asymptomatic

But may still be infectious

27% (16) who had antibodies and experienced symptoms didn’t have the 3 core NHS symptoms

Persistent cough

Fever

Anosmia

Specificity of anosmia for seropositivity was 95%

Compared to 88% for fever, cough and anosmia combined

However, loss of smell alone was still highly specific for having COVID-19, compared with the combination of all three symptoms

Additionally

Around half of the app users who reported symptoms that were highly predictive of COVID-19 did not have antibodies

Confirming other studies showing that current antibody testing misses a substantial fraction of cases

Not made, or fade quickly

Looking into T cells

A significant proportion of the population in London and the South East are likely to have been exposed to coronavirus

Many of them without showing any symptoms at all

It’s essential that we all take steps to protect the health of everyone by sticking to social distancing guidelines, wearing face coverings in public and following good hand hygiene practices

So if you have symptoms you can’t explain - get a swab or saliva test

Protect yourself and the people around you

These results suggest that both swab and antibody testing significantly underestimate the extent of coronavirus infections in the population

New AI diagnostic can predict COVID-19 likelihood without a test

Model is able to predict COVID-19 infection without patients having to be tested

By comparing them with people who have used the app to share their symptoms and the results of traditional COVID tests

Have great promise for populations where access to testing is limited

n = 2,618,862

18,401 had a SARS-CoV-2 test

7,178 of these came back positive

COVID-19 type symptoms most likely to be associated with a positive test

Wide range of symptoms caused by COVID compared to cold and flu

Danger of focusing only on fever and cough

Anosmia

Present in 66% of people testing positive

Present in 21 % of those testing negative

Anosmia is a stronger predictor of COVID-19 than fever

Mathematical model

Predicted with nearly 80% accuracy whether an individual is likely to have COVID-19 based on;

Age

Sex

A combination of four key symptoms: loss of smell or taste, severe or persistent cough, fatigue and skipping meals

Unwell app users

800, 000 app users unwell

17.42% were likely to have COVID-19 at that time

Prospective trials now underway

Jonathan Wolf

These initial results suggest that artificial intelligence diagnosis can help significantly without controversial privacy trade-offs

Professor Tim Spector

Our results suggest that loss of taste or smell is a key early warning sign of COVID-19 infection and should be included in routine screening for the disease

We strongly urge governments and health authorities everywhere to make this information more widely known

Advise anyone experiencing sudden loss of smell or taste to assume that they are infected and follow local self-isolation guidelines