A number of new publications show that a high proportion of people infected with COVID-19 report loss of smell and/or taste, with their authors adding to the clamor to recognize these symptoms as potentially indicative of the infection.
In particular, there is a belief that these signs may be present in many with asymptomatic COVID-19, and therefore asking about them could be a way to prioritize people for initial testing for the SARS-CoV-2 virus in the absence of other symptoms.
Anyone testing positive could then quarantine, and their contacts could be traced.
Despite this, the World Health Organization (WHO) has not listed loss of smell or taste as potential symptoms of SARS-CoV-2 infection.
But the US Centers for Disease Control and Prevention (CDC) has now added “new loss of taste or smell” as a symptom on its COVID-19 information page.
American Academy of Otolaryngology—Head and Neck Surgery (AAO-HNS) executive vice president and CEO James C. Denneny III, MD, believes the symptoms may be an early warning signal.
And there’s no downside to checking for these, Denneny told Medscape Medical News.
“Given the fact that this doesn’t require any surgical procedure, biopsy, or specific treatment, I think the upside of getting it early is great,” he said. “The downside of using it as a symptom, and if someone doesn’t turn out to have it, is virtually zero.”
Claire Hopkins, MD, president of the British Rhinological Society, and colleagues, writing in Lancet Infectious Diseases, agree.
“Physicians evaluating patients with acute-onset loss of smell or taste, particularly in the context of a patent nasal airway, should have a high index of suspicion for concomitant SARS-CoV-2 infection.”
They also observe that this appears to occur, in contrast to other respiratory infections, “in the absence of nasal congestion or rhinorrhea.”
Newest Publications Find Smell and Taste Loss Is Common
Author of one of the newly published studies, Carol H. Yan, MD, an otolaryngologist and head and neck surgeon at the University of California, San Diego, also thinks that sudden smell and taste loss seem to be fairly specific markers of COVID-19.
In her survey of patients who presented to UC San Diego Health for SARS-CoV-2 testing, Yan and colleagues reported that 68% (40 of 59) of COVID-19–positive patients reported olfactory impairment and 71% (42 of 59) reported taste impairment.
Among the 203 people in the “control” group who were polymerase chain reaction–negative (PCR–) for SARS-CoV-2, just 16% had smell loss and 17% had taste loss, according to their results published in the International Forum of Allergy & Rhinology.
“Based on our study, if you have smell and taste loss, you are more than 10 times more likely to have COVID-19 infection than other causes of infection. The most common first sign of a COVID-19 infection remains fever, but fatigue and loss of smell and taste follow as other very common initial symptoms,” said Yan.
“We know COVID-19 is an extremely contagious virus. This study supports the need to be aware of smell and taste loss as early signs of COVID-19.”
Yan told Medscape Medical News that another not-yet-published analysis indicates that sudden loss of smell or taste “may be more representative of a mild form of disease.”
Getting these people tested and isolated could therefore help prevent spread of COVID-19, she urged.
Based on Yan’s report and other case reports, the UC San Diego Health system is now asking all callers to its COVID-19 hotlines, and all visitors and staff, if they’ve had a sudden loss of taste or smell in the last few weeks, she explained.
And Ahmad R. Sedaghat, MD, PhD, at the University of Cincinnati, Ohio, takes a similar view.
In a new systematic review of the topic published April 14 in Laryngoscope Investigative Otolaryngology, Sedaghat and colleagues write: “Anosmia (total loss of smell) without nasal obstruction, in particular, appears to be a highly specific indicator of COVID-19.”
Sedaghat said a sudden loss of sense of smell wouldn’t necessarily lead people to think they have COVID-19, particularly if they remain asymptomatic, so “these individuals could continue business as usual and spread the disease as a carrier.”
“If someone experiences anosmia without nasal obstruction, aside from quarantining, it would not be unreasonable to reach out to one’s primary care physician about getting tested,” he said in a statement from his institution.