Symptom Checkers Add Weight
Several organizations around the world have begun collecting symptom reports from patients and clinicians, which has shone more light on the sudden loss of taste and smell as potential flags for COVID-19.
In an April 14 Morbidity and Mortality Weekly report from the CDC on COVID-19 infections in healthcare workers, of the 5000 who reported symptoms, 750 (16%) wrote “loss of smell or taste” as an “other” symptom.
Meanwhile, the COVID Symptom Tracker smartphone app, a joint effort by Massachusetts General Hospital, Boston, Stanford (Calif.) University, and King’s College, London, which as of press time, was monitoring some 2.5 million people, has had similar findings.
In a preprint publication on 400,000 people reporting one or more symptoms between March 24 and 29 on the tracker, 18% had lost their sense of smell or taste — more than the 10% who reported fever, but far less than the 53% who reported fatigue.
Only 1702 of the 400,000 had received a COVID-19 test.
Of those, 579 had tested positive and 1123 were negative.
The organizers estimated that of those who were positive, 59% reported losing smell or taste, compared with just 18% who tested negative.
“When combined with other symptoms, people with loss of smell and taste appear to be three times more likely to have contracted COVID-19 according to our data,” said Tim Spector, MD, a genetic epidemiologist at King’s College and the app’s lead researcher, on the symptom tracker’s website.
These people “should therefore self-isolate for 7 days to reduce the spread of the disease,” he urged.
Anosmia Is the Initial Symptom in Many Patients With COVID-19
The AAO-HNS also began collecting data from physicians and patients on March 25 through its Web-based 16-question symptom tracking tool.
It has received more than 500 reports of sudden taste or smell loss, said Denneny.
In a report on the first 237 responses, published in Otolaryngology-Head and Neck Surgery, anosmia (profound loss of smell) was found in 73% of subjects before a COVID-19 diagnosis and was the initial symptom in 27% of those subjects.
That latter determination “was the single most important finding,” said Denneny, noting it shows that smell and taste loss are “a sentinel symptom.”
Anosmia led to testing in only 40% of the cases.
Half of the reports came from otolaryngologists, but a large number came from other medical specialties, especially from family medicine.
Just 2% of reports came from patients in that first group, which was based on responses through April 3.
Denneny said that more reports are now coming in from patients, which he attributes to widespread media coverage about the loss of taste and smell.
It’s still not entirely clear why SARS-CoV-2 might inhibit taste or smell. More common viruses like influenza and other coronaviruses can also cause smell and taste loss.
So far, it seems like the sensory recovery is faster for SARS-CoV-2 than the other viruses, which suggests a potentially different mechanism of action, said Yan. Patients she surveyed at UC San Diego recovered the senses within a few weeks to a month, compared to months or a year with the more common viruses.
Yan’s study was partially supported by the National Institutes of Health. Sedaghat has reported no relevant financial relationships. The COVID Symptom Tracker is supported by Zoe Global Limited and has received grants from the Wellcome Trust, Medical Research Council/British Heart Foundation, and Biological Informative Markers for Stratification of Hypertension.
This article first appeared on Medscape.com.