COVID-19 Testing

The SAFER Study: What is the Risk to Healthcare Workers for COVID-19 During the Pandemic Peak?

BACKGROUND AND PURPOSE:

Houlihan et al. (The Lancet, 2020) evaluate the risk of HCWs contracting and transmitting COVID-19

Prospective cohort study (March 26 to April 8, 2020)
- SARS-CoV-2 Acquisition in Frontline Healthcare Workers—Evaluation to inform Response (SAFER)
Setting
- National Health Service hospital trust in London, UK
Participants
- Patient-facing healthcare workers (HCWs)
Study design
- Nasopharyngeal swabs were collected twice weekly for RT-PCR testing | RT-PCR tests were done twice a week
- HCWs symptom data were tracked

Total of 200 HCWs were enrolled
- Median age: 34 (IQR 29 to 44) years
- Evidence of COVID-19 at any time point: 44% (87 of 200 HCWs)
  - 21% had at least 1 positive RT-PCR test
  - Antibodies: 20% seroconverted and 25% were already seropositive at study entry
- No hospitalizations reported
Mean duration of SARS-CoV-2 detection: 12.9 days (95% CI, 9.4 to 17.3)
- Longest duration: 29 days
Trend towards a higher infection rate in younger HCWs <30 years (p=0.0199)
- <30: 55%
- >50: 33%
Asymptomatic carriage
- Symptoms within 7 days of positive test: 48%
- No symptoms within 7 days of positive test: 38%
Infection rates
- Infection rate within 1 month in those with negative RT-PCR test and without antibodies: 13% (14 of 112 HCWs)
- Infection rate in HCWs in those who had antibodies with negative RT-PCR at enrollment: 3% (1 of 33 HCWs)
- Most infections occurred during the week with the highest number of new cases in London

44% of HCWs had evidence of SARS-CoV-2 infection through RT-PCR or serology
- Higher than other international reports
- Percentage >2x that of the general population in London
The authors suggest that urgent policies are needed
- HCWs need adequate PPE
- Adequately protect against asymptomatic transmission into the general population from HCWs (through surveillance testing)

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