Leading infectious diseases clinicians have sounded the alarm over an observational study that prompted the WHO to suspend its trial of hydroxychloroquine treatment for COVID-19.

Last month, the Lancet published a multinational registry analysis of data showing the drug had no therapeutic benefit against the illness and increased the risk of death by 35-45%.

In addition to the WHO’s decision, the findings also influenced the Doherty Institute-led Australasian COVID-19 Trial (ASCOT) group to pause patient recruitment last week, pending a review by its governance and ethics committee.

But now, in an open letter published online, more than 100 international doctors, researchers and statisticians — including several Australians — have called on the Lancet and the study authors to address major “methodological and data integrity concerns”.