Table 2.

Studies included for preventive measures

Author and year	Study design	Country	Exposure/ prevention measure	Outcome/ evaluation tool	Main findings	Quality assessment
Cao et al, 20209	Qualitative interviews	China	HCW (n=37)/ Coping strategies as video chats or telephone calls with family and friends	Interview	Psychological support may help buffer negative impact on stress.	CASP (No: n=7, Yes: n=2)
Chen et al, 202039	Qualitative interviews	China	HCW (n=13), stress, influence on mental health/ psychological intervention medical team, hotline	Interview	Not scared to get infected, help for resting, skills to cope with patients’ anxiety and PPE shortage needed	CASP (No: n=5, Yes: n=2, can’t tell: n=2)
Chen et al, 202034	Ecological study	China	Caesarean delivery (n=17)/ appropriate PPE (N95 masks, goggles, protective suits, disposable caps, rubber gloves), if endotracheal intubation air-purifying respirator; negative operating room,	RT-PCR	No medical staff involved in operation were infected	GRADE: very low
Htun et al, 202036	Cross-sectional study	Singapore	Hospital overall (staff n=10 583)/ Fever and sickness surveillance for staff; risk-based PPE; enhanced surveillance for unwell staff	Mixed (clinical assessment, swabs for PCR)	No infection with COVID-19	AXIS: positive aspect n=10, negative n=4, don’t know n=6
Huang et al, 202035	Ecological study	China	Nurses, 35 confirmed, 260 suspected cases/ PPE (hat, respirator, inner gloves, eye mask, protective clothing. Shoe covers, isolation gowns, outer gloves, face shield), hand hygiene, ward disinfection, medical waste management, sterilisation of patient care devices, management of occupational exposure. Teaching. Shift schedule evaluated; psychological counselling	Not specified	Zero infection rate in nurses	GRADE: very low
Huang et al, 202030	Ecological study	China	Radiology department, 3083 suspected or confirmed COVID-19 patients/ Reconfiguring of the department, PPE (protective clothing, surgical cap, N95 mask, gloves, face shields, goggles), training, donning and doffing under supervision, strategic planning of examination procedures	Clinical symptoms	None of the staff became infected.	GRADE: very low
Kabesch et al, 202038	Ecological study	Germany	Outbreak scenario, midwife → colleagues / Face masks, social distancing in cafeteria and break rooms, on site visits hygiene experts, staff training, transparent, timely and direct communication, testing all symptomatic employees	Laboratory test for symptomatic staff	Successful containment of the outbreak within 3 weeks, 36 staff members tested positive	GRADE: very low
Malik 202033	Ecological study	Pakistan	Admission of a COVID-19 positive patient to the ICU/ HCW with N95 or surgical masks	PCR	All HCW (n=34) tested negative for COVID-19	GRADE: low
Ng et al, 202032	Ecological study	Singapore	one patient with pneumonia/ HCW (n=41) exposed during aerosol-generating procedures	Clinical monitoring and PCR	No HCW infected	GRADE: low
Wee et al, 202031	Ecological study	Singapore	Emergency department, PCR tests for all patients with respiratory syndromes, n=70 patients tested positive/ PPE risk stratified	PCR testing, extensive surveillance	No nosocomial transmission	GRADE: low
Zhu et al et al, 202037	Ecological study	China	one patient with endonasal adenoma resection, general care and operation/ no prevention measures initially before confirmed infection	Diagnosis of infection not specified.	four nurses without prevention measures (and 10 persons without contact to the patient) got infected, none of the persons in the operation room or under specific prevention got infected.	GRADE: very low

AXIS, Appraisal Tool for Cross-Sectional Studies; CASP, Critical Appraisal Skills Programme; GRADE, Grading of Recommendations, Assessment, Development and Evaluations; HCW, healthcare worker.