Extending Symptoms Could Help Detect More COVID-19 Cases

Recent research published in the Journal of Infection has suggested that only testing for the classic triad of coronavirus disease 2019 (COVID-19) symptoms, which are cough, fever and loss of smell, may lead to missed cases. The investigation was conducted by the King's College London and the Coalition for Epidemic Preparedness Innovations (CEPI).

"We've known since the beginning that just focusing testing on the classic triad of cough, fever and anosmia misses a significant proportion of positive cases,” Tim Spector, a professor from King’s College London said. “We identified anosmia as a symptom back in May and our work led to the government adding it to the list, it is now clear that we need to add more.”

The team gathered and analyzed data from 122,000 adults in the United Kingdom who used the ZOE COVID Symptom Study app to report any experienced COVID-19 symptoms. 1,202 of the users reported a positive PCR tests within a week of feeling ill.

The investigators employed a multi-objective evolutionary algorithm (MOEA) and generated a set of optimal symptom combinations, characterized by a trade-off between sensitivity and specificity. A random combination of symptoms was then generated which evolved to find better combinations and ended with optimal symptom combinations, which can be used find which will work for which type of test.

“There are many symptoms which occur in acute COVID, including some like fatigue and headache which are also common in other conditions,” Claire Steves, a reader at King’s College London said. “Depending on the testing available, different symptom combinations can be used to be as sensitive or specific as possible.”

Findings showed that if only using the classic 3 symptoms, 69% of cases would have been spotted. If the list were increased to any of 7 key symptoms, including fatigue, headache, sore throat and diarrhea, 96% of symptomatic cases would be able to be detected. Additionally, the investigators found that the users of the app were more likely to select headache and diarrhea within 3 days of symptom on set and fever during the first 7 days. 31% of people who had a case of COVID-19 did not show any of the classic 3 symptoms.

"Accurate diagnosis of COVID-19 cases is crucial when assessing the efficacy of COVID-19 vaccine candidates in large-scale studies, especially since the signs and symptoms associated with the disease are extensive and overlap with other common viral infections,” Jakob Cramer, Head of Clinical Development, at the Coalition for Epidemic Preparedness Innovations said. The findings of this study provide important insights that will help optimize the choice of triggering symptoms for diagnostic work-up in COVID-19 vaccine-efficacy trials.”