Almost two-thirds of staff at a London NHS trust reported losing their sense of smell before the symptom was added to national guidance as a coronavirus symptom, it has emerged.
Researchers asked staff at London’s Barts Health NHS Trust to complete a questionnaire in the week of April 17 to 23, at the height of lockdown.
At this time anosmia – a loss of taste or smell – was not listed as an official symptom and Covid-19 testing among NHS workers was limited to those displaying symptoms of a new continuous cough or a high temperature over 37.8C.
Public Health England added anosmia to the list on May 18, after which staff displaying the symptom were required to test and self-isolate for seven days.
The research, led by the University of East Anglia in collaboration with University College London, found that 168 out of the 262 healthcare workers who completed the questionnaire reported losing their sense of smell or taste at some point.
Just 73 (27.9 per cent) of the 262 participants had been tested for Covid-19 at the time, with 56 of these (76.7 per cent) confirmed positive.
Senior author Prof Carl Philpott, from UEA’s Norwich Medical School, said of the research: “This suggests that a large proportion of healthcare workers may have already been infected with Covid-19, with only mild symptoms.
“We conducted this research at Barts Health, however we would expect to see similar results from other NHS trusts too. Cases like this most likely went undiagnosed at the time because of a lack of awareness about smell loss as a symptom.
“This is really important because healthcare professionals are at the front line of the pandemic and are at high risk of both contracting and spreading coronavirus.
“There is a need for awareness and early recognition of anosmia as a means to identify, urgently test and isolate affected healthcare workers in order to prevent further spread of disease.”
He explained that data also suggested a “strong association between smell loss and the positive Covid-19 test results”, with those who had lost their sense of smell being almost five times more likely to test positive.
The study also involved a follow-up survey in May, in which 47 per cent of respondents reported that their sense of smell and taste had completely recovered.
Some 42 per cent reported they had partially recovered their sense of smell and taste, but just over seven per cent were still experiencing the loss.
The survey has also been running in two Norfolk hospitals and in two hospitals in the North West with the responses of more than 1,000 healthcare workers due to be published soon.
The research is published in journal The Lancet Microbe.
