Fig. 1
Flow chart of sample selection. * Data from 2 weeks prior to COVID-19 infection were used, and when unavailable, consecutively further weeks prior, up to 6 weeks, were used
Fig. 1 | BMC Public Health
Flow chart of sample selection. * Data from 2 weeks prior to COVID-19 infection were used, and when unavailable, consecutively further weeks prior, up to 6 weeks, were used