Public Health England says the two main symptoms of Covid-19 are a new and continuous cough and / or a high temperature.
The World Health Organization says other indicators are fatigue, aches and pains, stuffy nose, sore throat, and diarrhea.
But now some British doctors are asking for an urgent addition to the list: sudden and complete loss of smell.
New data collected by ENT UK, which represents ear, nose and throat specialists, suggests that this inability to smell – and often taste – may be the very first symptom and begin in hours.
Doctors warn that odor loss may be a sign of coronavirus (stock image)
Many people don’t seem to develop any further symptoms, causing them to fully recover without even realizing they had Covid-19. It is thought to be mostly healthy young adults whose immune systems respond enough to the virus to trap it in the nose, preventing it from spreading to the lungs, where it can potentially cause fatal pneumonia.
As a result, ENT UK warns, some Covid-19 patients are not identified as infected or advised to isolate themselves – and may spread the virus to others.
“I have seen a massive increase in the number of patients visiting my clinic with a sudden loss of smell,” said Professor Nirmal Kumar, President of ENT UK and an ear, nose and throat specialist at Wrightington, Wigan and Leigh NHS Trust.
It’s about four patients a week, usually under the age of 40 and with no other Covid-19 symptoms. I usually don’t see more than once a month. ‘
Professor Kumar advises patients with no apparent explanation for their odor loss to isolate themselves for at least seven days in case they have Covid-19, even if this is not the current government recommendation.
But doctors are also raising the alarm because one of the first-line treatments for anosmia (complete loss of smell) or hyposmia (partial loss of smell) is a one-week course of steroid tablets.
These drugs help dampen inflammation that can press on the olfactory nerves – those in the head that process odor signals to the brain. But steroids also suppress the immune system. Therefore, ENT specialists are now worried that patients with “hidden” coronavirus may have a harder time recovering from the infection if doctors prescribe steroids for their odor loss.
ENT UK says there is good evidence from abroad that the number of Covid-19 patients experiencing this symptom is “significant.” A statement sent to Public Health England in mid-March said: “In Germany, it is reported that more than two in three confirmed cases have anosmia.
“And in South Korea, 30 percent of patients who tested positive for Covid-19 had anosmia as their main presenting symptom.”
Up to 40 percent of anosmia cases are caused by a viral respiratory infection due to a cold, flu, or sinusitis – an infection of the narrow tubes in the nasal cavity. But it usually develops after an infection.
With Covid-19, the fragrance seems to be influenced from the start, says Dr. Tony Narula, a former president of ENT UK.
ENT UK leads the call to identify the loss of smell and taste as one of the main symptoms of a coronavirus infection (stock image)
“Normally with a cold or flu virus, you get a stuffy nose and you lose some odor because you can’t get air (that involves odors) into the nostrils,” he says.
“It’s different with Covid-19. The virus appears to strike directly on the olfactory nerve on the roof of the nose, just between the eyes.
“One of the reasons so many people suffer is that this nerve is not covered with protective tissue, so the virus attacks it and causes inflammation that stops the smell signals from reaching the brain.”
Dr. Narula recently saw a young patient complaining of sudden loss of smell. Concerned that it would be a tumor pressing on the nerves that connect the olfactory nerve to the brain, he ordered a scan of the patient’s head.
After it clearly came back, the patient was told there was no clear explanation and that his sense of smell was likely to return in a few weeks.
“About ten days later,” says Dr. Narula, “I started hearing reports of Covid-19 patients showing up with anosmia, and emailed my patient to inform him.
“He had since flown abroad, where he felt unwell and tests showed he had coronavirus.”
A person is tested for coronavirus in the drive-in facility at Chessington World of Adventures
Dr. Narula says that most Covid-19 patients fully recover their odor within four to six weeks, and the loss of taste that many patients also report is actually caused by odor absorption problems. Taste buds, usually found on the tongue, are not affected by the virus.
“About 80 percent of the taste is actually due to smell, from aromas in the back of the mouth that circulate in the nose,” he says.
“We are concerned that we have brought this issue to the attention in the past two weeks and that public health still does not mention England’s sudden loss of smell as a symptom. We must spread the message. ‘
A Public Health England spokesperson was unable to say whether anosmia would be added to the official list of Covid-19 symptoms.