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COVID-19 ISO Insights

UK COVID-19 Confirmed Cases May Be Missing Some

March 1, 2021

By: Christopher Sirota, CPCU

Back in October 2020, Nature reported that researchers had developed a database to collect global data on confirmed cases of COVID-19 from over 94 countries based on PCR test data—the test reportedly recommended by the World Health Organization (WHO).

But if some countries limit the PCR test to patients by certain symptoms, how might that affect the COVID-19 detection rate?

Now, Science Daily has reported on a study that evaluated the detection rate of COVID-19 in the population of the United Kingdom based on the National Health Service (NHS) symptom criteria for administering the PCR test. (Daily updates for the UK PCR test results are available here)

According to Science Daily, currently PCR testing by the NHS is restricted to patients that exhibit three symptoms: cough, loss of smell, and a fever. However, based on a study of data from 122,000 adults, researchers have concluded that if the list of symptoms were extended to include sore throat, headache diarrhea and fatigue, COVID-19 detection rates would likely increase from about 69% to nearly 96%.

Notably, per the article:

Researchers also found users of the [ZOE] Symptom Study App were more likely to select headache and diarrhea within the first three days of symptoms, and fever during the first seven days, which reflects different timings of symptoms in the disease course. Data from the ZOE app shows that 31% of people who are ill with COVID-19 don't have any of the triad of symptoms [cough, loss of smell, fever] in the early stages of the disease when most infectious.

The researchers also reportedly noted that new variants of the virus could cause different symptoms making the collection self-reported symptoms via a mobile app at a national level seem even more valuable.

(See Our World in Data's COVID-19 testing web page for an updated by-country comparison which includes PCR and antigen testing data)

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