Maternity staff should get regular coronavirus tests, scientists have said, as a study reveals one in six have contracted the disease, with a third of cases asymptomatic.
The fact that so many showed no signs of having caught the virus allowed them to go about the wards as usual, potentially passing it to mothers and new babies, University College London scientists warned.
The study, published in the journal Anaesthesia, examined infection rates among staff in maternity units at two London hospitals.
In total, 200 anaesthetists, midwives and obstetricians from University College London Hospital and St George’s Hospital, with no previously confirmed diagnosis of Covid-19, were given antibody tests, which show whether or not a person has previously been infected.
Of these, 29 were found to have previously been infected. Only six had a fever and 10 recalled having a cough. Fifteen of them suffered anosmia, a loss of sense of taste or smell.
Ten had no symptoms whatsoever. Among all of those who were found to have previously been infected, 59 per cent had not self-isolated at any point and had continued to provide care to patients.
The authors wrote: “This has significant implications for the risk of occupational transmission of SARS-CoV-2 for both staff and patients in maternity units. Regular testing of staff, including asymptomatic staff, should be considered to reduce transmission risk.
“Until we have robust evidence as to the risk posed by asymptomatic infected individuals to others, and as to the risk of Covid-19 to babies, particularly during pregnancy, our study suggests that extreme caution is advisable in maternity settings, particularly the consistent use of effective personal protective equipment and other known effective measures including social distancing of staff and the regular washing of hands.
“We also recommend that all obstetric healthcare institutions should consider regular serology testing for staff, as well as the immediate isolation of any staff who lose their sense of taste and smell, even in the absence of cough or fever.”
At the beginning of the pandemic, the Government advised all those with a persistent cough or fever above 38.8C to self-isolate. The new study shows that only 41.4 per cent of healthcare workers who tested positive for Covid-19 antibodies met those criteria and self-isolated at any point.
The data showed that, in this population, neither cough nor fever predicted signs of previous infection, and that the only symptom of a positive test was loss of taste and smell. The Government has since added this symptom to the list that mandate self-isolation.
“Regular testing and consistent use of PPE are likely to be the cornerstones of pandemic control,” the authors concluded.
UCL is now embarking on a study of 6,000 pregnant women across the UK in an effort to establish whether Covid-19 increases the chance of miscarriage.
Their research coincides with a paper by the University of East Anglia (UEA) looking at asymptomatic levels in care homes.
The team found that roughly half of care home residents who tested positive for Covid-19 in Norfolk homes were asymptomatic, but some went on to develop symptoms.
According to the study by UEA and North Norfolk Primary Care, supported by UEA Health and Social Care Partners, in many cases symptoms were not typical and did not include a high temperature, cough or loss of smell.
Instead, residents who tested positive for Covid-19 often presented as generally unwell, researchers say in the study, which has not yet been peer-reviewed.