Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre-including this research content-immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.

No abstract

Progressive multifocal leukoencephalopathy (PML) is a viral infection predominantly seen in patients with HIV infection. However, with the increased use of monoclonal antibodies (MAB) for various lymphoproliferative disorders, we are now seeing this infection in non-HIV patients on drugs such as natalizumab, rituximab, and so on. The aim of this article is to review the relationship between the occurrence of PML and MAB used in the treatment of hematological malignancies and autoimmune diseases. Review of articles from PubMed-indexed journals which study PML in relation to the use of MAB. Relevant literature demonstrated an increased risk of reactivation of latent John Cunningham polyomavirus (JCV) resulting in development of PML in patients on long-term therapy with MAB. The highest incidence of 1 PML case per 1000 treated patients and 1 case per 32 000 was observed in patients treated with natalizumab and rituximab, respectively. Serological and polymerase chain reaction tests for the detection of JCV can be helpful in risk stratification of patients for the development of PML before and during therapy with MAB. Treatment with MAB can result in development of PML. Clinicians should include PML in differential diagnosis in patients treated with these agents if they manifest central nervous system symptoms.