Combination of Symptoms predicts COVID-19: anosmia (loss of smell), fever, persistent cough, fatigue, diarrhoea, abdominal pain and loss of appetite together with 86% specificity

Coronavirus by Engin Akyurt via pixabay.com (open access)

A study reported in BioRxiv on April 7 looked at using a combination of symptoms to predict infection with SARS-COV-2 and COVID in a UK (United Kingdom) community survey  of 1,573,103 individuals, roughly 26% of whom said they had at least one symptom.  They found that reports of multiple symptoms predicted infection with a greater likelihood than individual symptoms.  Anosmia (loss of sense of smell and taste) was present in 59% of patients with confirmed infection; this symptom is a more recently recognized one.  The group of symptoms that best predicted presence of the virus was the following:

… a combination of loss of smell and taste, fever, persistent cough, fatigue, diarrhoea, abdominal pain and loss of appetite is predictive of COVID-19 positive test with sensitivity 0.54[(range) 0.44; 0.63], specificity 0.86[(range) 0.80; 0.90] …

This specific combination of symptoms had not previously been reported to predict infection, but this large community survey confirms that there is a set of symptoms that together makes the diagnosis much more likely.  Given that detection of the virus by nasopharyngeal swabs is not as sensitive as we would like (roughly 74% of victims have positive swabs on day eight after exposure) and depends on exactly when the test is done, we need a set of symptoms to guide us in presumptive identification of cases for isolation in the absence of universal testing.

Other symptoms, such as body aches (myalgia), headache, confusion, shortness of breath (dyspnea), chest pain, and productive cough, are also associated with COVID-19. They may relate to other manifestations such as pneumonia (possibly related to immune reaction) and brain infection (a feared but rare complication).  The main symptoms of abdominal pain and diarrhea point to the presence of gastrointestinal (GI) (stomach and guts) infection as a primary factor in addition to the nasopharyngeal (nose and throat) route.  GI infection has been suspected since fecal (stool) specimens have shown virus to be present in acutely ill patients.

This report suggests that patients with this combination of symptoms are the most likely to have the virus, although sensitivity is still poor at about 54%.  RT-PCR testing of nasopharyngeal swab specimens to detect acute cases and blood antibody tests (a combination of IgG (chronic) and IgM (acute) antibodies) are needed to accurately outline the incidence and prevalence (new cases at any moment and overall number of cases) of COVID due to SARS-COV-2.

Other reports from early in the pandemic of wide community spread suggest that trivial or asymptomatic (no apparent illness) cases represent a major proportion of people with this virus, possibly as many as half.  SARS-COV-2 may have been spreading widely on the West and East Coasts long before we realized that it was even present at all.  Infected people without symptoms may have introduced the virus to the US early in January at the latest.

We were already far behind this virus when the first federal action was taken, a partial ban on travel from China, in late January.  Warnings from the intelligence community in late December and early January were ignored.  We have been playing “catch-up” ever since, a losing battle given the disorganized and tardy federal response.  Even now, the administration is co-ordinating the sourcing of equipment through favored large companies and personal connections at great public cost.  This is a subject for another post.