SARS-CoV-2 transmission among health care workers, an outbreak investigation using whole-genome sequencing

BACKGROUND

We report an outbreak investigation to map intra-hospital transmission among health care workers (HCW) using epidemiological and whole-genome sequencing data.

METHODS

Fourteen clinical wards (COVID-19 and non-COVID-19) with high infection rates of SARS-CoV-2 among HCW were selected and demographical, epidemiological and sequencing data were collected of all HCW testing positive by RT-PCR. Clustered cases were identified based on first disease onsets and differences in single nucleotide polymorphisms (SNP's) and were analysed for additional characteristics.

RESULTS

Data was collected for 123 HCW. Out of 123 HCW, 65 (53%) worked at eight non-COVID-19 wards, 56 (46%) at four COVID-19 wards, one (<1%) worked on several wards and for one (<1%) it was unknown. One major cluster (n = 34) and three minor clusters (n = 2,3,4; total n = 9) comprising of 43 HCW (35%) were found after comparing our study population (n = 123) with the circulating regional sequences (n = 819). In clustered cases work was most often the suspected source of infection and continuing work while having symptoms occurred in all clusters, ranging from 1-6 days.

CONCLUSION

Our findings strongly indicate transmission of SARS-CoV-2 among HCW. Whole-genome sequencing is useful for identification of clusters and can give direction to targeted infection prevention measures.

[Human T-cell lymphotropic virus type 1 (HTLV-1): a forgotten pathogen]

HTLV-1 is a retrovirus endemic to different parts of the world that causes a variety of symptoms, ranging from asymptomatic infection to severe diseases such as lymphoma/leukaemia and myelopathy. HTLV-1 is transmitted from mother to child through breastfeeding, sexually and via blood and organ donation. We describe 3 patients as examples of the distinct clinical problems related to HTLV-1: a 53-year-old woman with HTLV-1-associated myelopathy, a 43-year-old woman with acute T-cell lymphoma and a 34-year-old pregnant woman who is an asymptomatic carrier. It is not known how many people are infected in the Netherlands, but it is probably more prevalent among immigrants from the Caribbean and Surinam and likely to be underdiagnosed. Diagnosis is important because it alters treatment and because measures to prevent transmission can be implemented, e.g. refraining from breastfeeding and safe sex precautions.