By Denise Baez
A study that tested 200 obstetric healthcare professionals, including anaesthetists, midwives, and obstetricians, for immune seroconversion found that 14.5% had been infected with severe acute respiratory syndrome coronavirus (SARS‐CoV‐2) as revealed by the presence of IgG antibodies, of which 35% were completely asymptomatic and 59% had not self‐isolated at any point and continued to provide patient care in the hospital setting.
The findings, published in the journal Anaesthesia, have significant implications for the risk of occupational transmission of SARS‐CoV‐2 for both staff and patients in maternity units.
“Given that third‐trimester pregnancy care involves multiple ongoing encounters with healthcare professionals and a potentially high proportion of reported asymptomatic carriers, obstetric healthcare professionals may be at an elevated risk of patient‐to‐staff, staff‐to‐staff and staff‐to‐patient transmission,” wrote Sohail Bampoe, MD, University College London Hospitals NHS Foundation Trust, London, United Kingdom, and colleagues. “Regular testing of staff, including asymptomatic staff should be considered to reduce transmission risk.”
Between May 11, 2020, and June 5, 2020, Dr. Bampoe and colleagues tested healthcare professionals at 2 tertiary‐level maternity units in London and conducted a comprehensive investigation of symptoms and medical histories. Of the 40 anaesthetists tested, 5 (12.5%) tested positive for IgG antibodies against SARS-CoV-2, as did 7 of 52 (13.5%) obstetricians and 17 of 108 (15.7%) midwives.
Of those who had seroconverted, 10 (35%) were completely asymptomatic. Only 6 (21%) healthcare workers had fever and only 10 (35%) experienced cough. Anosmia was the most common symptom occurring in 15 (52%) seropositive participants and was the only symptom that was predictive of positive seroconversion (odds ratio = 18; 95% confidence interval, 6-55).
Of the seropositive participants, 12 (41%) had self‐isolated at least once during the pandemic. Of these, 17 (59%) had continued to work throughout the period, either because they were asymptomatic (n = 10) or their symptoms did not qualify them at the time for self‐isolation (n = 7).
“This is the largest study to report baseline immune seroconversion to SARS‐CoV‐2 in obstetric healthcare workers to date,” the authors wrote. “Our data revealed that only 41% of healthcare workers who were seropositive met those criteria and self‐isolated at any point. This means that 59% continued to work and commute despite active SARS‐CoV‐2 infection. Indeed, our data showed that in this population, neither cough nor fever predicted seropositivity and the only symptom predictive of immune seroconversion was anosmia. The UK Government has since added anosmia as a symptom that mandates self‐isolation. Our study strongly supports this updated advice, albeit it would still fail to isolate approximately 6 of 10 infected staff members. Of importance, it was not until June 15 that all staff members in patient‐facing areas were advised by Public Health England to wear surgical masks to reduce the risk of infection to others.”
“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 in utero, our study suggests that extreme caution is advisable in maternity settings, particularly the consistent use of effective personal protective equipment,” the authors advised. “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 develop anosmia, even in the absence of cough or fever. Regular testing and consistent use of personal protective equipment and hand‐washing are likely to be the cornerstones of pandemic control.”