NIH halts COVID-19 convalescent plasma trial

The US National Institutes of Health (NIH) has stopped a trial evaluating the safety and efficacy of COVID-19 convalescent plasma in treating emergency department patients who developed mild to moderate symptoms of COVID-19.

The trial was halted following the second planned interim analysis by the independent data and safety monitoring board (DSMB). In the analysis the DSMB determined that, while the convalescent plasma intervention caused no harm, it was unlikely to benefit this group of patients and therefore recommended that the trial be stopped. The National Heart, Lung, and Blood Institute (NHLBI), the part of NIH that was conducting the study, did so immediately.

The Clinical Trial of COVID-19 Convalescent Plasma of Outpatients (NCT04355767) began in August 2020 and enrolled 511 patients across 47 hospital emergency departments in the US. To be enrolled patients had to have mild to moderate symptoms of COVID-19, not be ill enough to require hospitalisation and have at least one risk factor associated with severe COVID-19 (eg, obesity, hypertension, diabetes, heart disease or chronic lung disease).

After the study participants received either the COVID-19 convalescent plasma or a placebo, researchers tracked whether the participants needed to seek further emergency or urgent care, had to be hospitalised or died within 15 days. The interim data analysis indicated no significant difference in the proportion of participants who experienced any one of these outcomes. Therefore the DSMB concluded that even if enrolment continued, the trial was highly unlikely to demonstrate that COVID-19 convalescent plasma prevents progression from mild to severe illness in at-risk emergency department non-hospitalised participants.

Convalescent plasma is blood plasma collected from patients who have recently recovered from COVID-19 and therefore it contains neutralising antibodies targeting SARS-CoV-2 – the virus which causes COVID-19.