Pharmacy times interviewed Kai Zhao, PhD, director of the Nasal Physiology and Therapeutic Center in the Department of Otolaryngology at Ohio State University College of Medicine, about the dangers of loss of taste and smell in patients infected with COVID-19.
Alana Hippensteele: Hi, I’m Alana Hippensteele with Pharmacy times† With me is Kai Zhao, PhD, director of the Nasal Physiology and Therapeutic Center in the Department of ENT at Ohio State University College of Medicine and senior author of a study recently published in med which showed that loss of smell and taste is a common COVID-19 symptom that can last longer than patients realize.
So dr. Zhao, based on your research findings, how long can the loss of taste and smell last for patients who have had COVID-19?
Kai Zhao: Yes, based on the study, I think this is a very broad spectrum of disease duration. So some of our patients who have COVID, even during the first wave, which is March 2020, still have a loss of smell. So we don’t know exactly how long they can have it for every patient, but we think there can be a range of symptoms with this duration – some can recover very quickly, [such as] within a few days or even 2 weeks, [but] some can last for months, even years. The exact frequency or prevalence of these patients is, I believe, unknown.
Alana Hippensteele: What did your findings show regarding how many patients were or were not aware of the ongoing loss of taste and smell after COVID-19 infection?
Kai Zhao: I think we can say it is higher than the background or the normal general population. So we have about 50% of patients who have previously had COVID-19 and who report no sustained loss of smell or taste, but objectively we find that they have loss of smell at the time of testing. Some of them, as I said, had the disease even years before, and by then they are free of the virus, but still they have some objective losses.
I think this could lead to a public health awareness [issue]because I think for the medical field, as well as for public health, smell and taste are our least [assessed sense in the] odor sensory system. For example, every newborn baby gets a hearing test to see if he or she has a hearing impairment. I get an eye exam every year, but no one gets a taste or smell exam. So we don’t know objectively how these patients are doing, even though some subtle losses may not even have been realized.
For example, some elderly people who have hearing loss are not aware of hearing loss. So even visual losses, or some vision problems, you probably don’t know where. So I think we need to raise awareness, maybe we need more objective monitoring of disease course and impact, especially on the smell and taste functions.
Alana Hippensteele: What are the implications of this lack of awareness regarding the persistence of this symptom for patients?
Kai Zhao: Well, I think we might be overlooking some of the effects of smell and taste loss on the population. So we now have a large population that has now had COVID-19, and there could be a large number of patients with odor loss that we are overlooking. This can affect their dietary intake or food intake and it can have other health consequences that we are not aware of.
The only major concern I have for people with a loss of smell and taste is that they may not be able to detect a gas leak – and that could be a hazard – or detect fire or detect dangerous chemicals. There are some workers who test solvents, and we have patients who have been knocked unconscious while working in a closed environment with solvents or chemicals that they were not aware of. So people with good scent function can detect that and leave or vent, but some patients with scent loss can’t detect that environmental hazard and that could be a real risk to them.
Alana Hippensteele: As a follow-up, if a patient wants to assess loss of smell and taste, how would he go about it?
Kai Zhao: I think there are commercially available testing tools. The one we use is the [National Institutes of Health (NIH)] toolbox. So the problem is that many health clinics don’t routinely test for smell and taste and don’t have the right objective tools. So hopefully, by raising awareness, more clinics will buy these objective tools, including the NIH toolbox, or there’s the University of Pennsylvania odor identification test, which is also commercially available. Then they can do more tests on patients to let people know the status of their sensory function.