“There are daily reports of recovery from long haulers in terms of parosmia improving and patients being left with a fairly good sense of smell,” Professor Hopkins said.
Ms. Viegut, 25, worries that she may not be able to detect a gas leak or a fire. That is a real risk, as shown in January by the experience of a family in Waco, Texas, that did not detect that their house was on fire. Nearly all members had lost their sense of smell because of Covid; they escaped, but the house was destroyed.
Parosmia is one of several Covid-related problems associated with smell and taste. The partial or complete loss of smell, or anosmia, is often the first symptom of the coronavirus. The loss of taste, or ageusia, can also be a symptom.
Before Covid, parosmia received relatively little attention, said Nancy E. Rawson, vice president and associate director at the Monell Chemical Senses Center in Philadelphia, an internationally known nonprofit research group.
“We would have a big conference, and one of the doctors might have one or two cases,” Dr. Rawson said.
In an early 2005 French study, the bulk of 56 cases examined were blamed on upper respiratory tract infections.
Today, scientists can point to more than 100 reasons for smell loss and distortion, including viruses, sinusitis, head trauma, chemotherapy, Parkinson’s disease and Alzheimer’s disease, said Dr. Zara M. Patel, a Stanford University associate professor of otolaryngology and director of endoscopic skull base surgery.