Ebola vaccine halt 'a precaution' say researchers

Some patients have reported joint pains

A trial of an experimental vaccine against Ebola in development at NewLink Genetics has been halted after some patients reported joint pains.

The rVSV-EBOV vaccine - which was licensed to Merck & Co last month - is one of two vaccines accelerated into clinical trials in a bid to tackle the Ebola outbreak currently affecting several West African countries.

The phase I trial involving 59 volunteers was being conducted at the University of Geneva Hospital in Switzerland, and was halted a week early "as a measure of precaution", according to the investigators, who stressed that minor aches and pains are quite commonly seen with vaccines.

The four patients reporting joint pain are otherwise fine, according to the Swiss team, but checks are being undertaken to make sure that the symptoms are transient and not associated with any underlying adverse reaction. It is anticipated that the trial will resume within a few days, with another 15 patients scheduled to receive the shot.

Other trials of the vaccine in the US, Germany, Canada and Gabon have not encountered any untoward symptoms and are continuing as planned.

Scientists testing another Ebola vaccine candidate - GlaxoSmithKline's ChAd3-EBO, said the safety data from ongoing trials was very encouraging. The vaccine has also been shown to stimulate an immune response during phase I trials.

Meanwhile, Johnson & Johnson (J&J) is also stepping up production of its own candidate - being developed by subsidiary Crucell in partnership with the Danish biotech Bavarian Nordic and the US National Institutes of Health - and has said it plans to start trials by next May.

The researchers are racing to bring an effective vaccine through development in order to protect healthcare workers battling the outbreak and - in time - start vaccination programmes to try to quell the spread of the virus.

At last count, the World Health Organization (WHO) has reported 17,942 cases of Ebola virus disease (EVD), with 6,388 deaths concentrated mainly in Guinea, Liberia and Sierra Leone, although those numbers could spike after a flurry of new cases in the Kono district in east Sierra Leone.

The vaccine charity Gavi pledged this week to make $300m available to buy Ebola vaccines and support large-scale vaccination efforts "as soon as a safe, effective vaccine is recommended for use by the WHO."

An additional $90m could be deployed to support countries to introduce the vaccines and to rebuild devastated health systems and restore immunisation services for all vaccines in Ebola-affected countries, it added.