A large proportion of healthcare workers in England may have been infected with Covid-19 between mid-February and mid-April, researchers have said.
Led by the University of East Anglia in collaboration with University College London, a study found that two-thirds of respondents to a survey across one of the largest NHS trusts in the UK had experienced a loss of their sense of taste and smell during the time period.
This was before the Government included the symptom among those which would have enabled NHS staff to have a Covid-19 test, which did not happen until May.
The research team distributed questionnaires to staff at London’s Barts Health NHS Trust, reaching 262 respondents across four hospitals in the week of 17-23 April.
Senior author Professor Carl Philpott, from UEA’s Norwich Medical School, said: ‘The really interesting thing that we found was that 168 of the participants – nearly two thirds – said that they had lost their sense of smell or taste at some point between mid-February and mid-April.
‘We also found 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.
‘This suggests that a large proportion of healthcare workers may have already been infected with Covid-19, with only mild symptoms.’
He added that although the research was only conducted across one large hopsital trust, the researchers ‘would expect to see similar results from other NHS trusts too’.
Professor Philpott said: ‘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 frontline 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.’
The study, published today in The Lancet Microbe, said: ‘To date, testing for health-care workers in the National Health Service has been scarce and only recently has been made more widely available.
‘Thus, a large proportion of healthcare workers might have already been infected with SARS-CoV-2 and had only mild symptoms, resulting in only a small number of health-care workers being tested.
‘In conclusion, awareness and early recognition of anosmia and hyposmia is needed to identify, urgently test, and isolate affected health-care workers to prevent further spread of disease.’
In a follow-up survey in May, 47% of the respondents said their sense of smell and taste had completely recovered, 42% said it had partly recovered, while 7% still suffered anosmia.
The survey has also been running in two Norfolk hospitals and in two hospitals in the North West with the responses of over 1,000 healthcare workers due to be published soon.
The research was led by UEA in collaboration with Whipps Cross University Hospital (part of Barts Health NHS Trust), University College London, the Royal National ENT and Eastman Dental Hospitals (part of UCLH NHS Foundation Trust) and the Norfolk Smell & Taste Clinic, at Norfolk & Waveney ENT Service.