Merck & Co said today that updated data from the study of its experimental Covid-19 pill showed lower efficacy in reducing the risk of hospitalisation and deaths than an earlier interim analysis, cutting them by 30 percent in the study.

The drugmaker released interim data last month showing a roughly 50 percent reduction in hospitalisations and deaths in 775 patients. The updated rate today is based on data from over 1,400 patients.

Merck's shares fell three percent to $79.41 in premarket trading, amid a fall in the broader markets.

The company said data on the drug molnupiravir...