An asymptomatic elderly woman with chronic lymphocytic leukaemia tested positive to coronavirus for a landmark 105 days, and remained infectious for much of that time, US researchers are reporting.

The case highlights the risk of immunocompromised patients shedding infectious virus for longer than expected because of their impaired ability to mount an immune response, say the researchers from the National Institute of Allergy and Infectious Diseases.

The 71-year-old woman – who also had a 10-year history of acquired hypogammaglobulinaemia, anaemia and chronic leukocytosis – is believed to have become infected with SARS-CoV-2 while recovering from spinal surgery at a rehabilitation facility that experienced a large COVID-19 outbreak.

She tested positive to the virus in early March when she was screened after being rehospitalised with severe anaemia, the researchers report in Cell.