FRANKFURT: German biotech firm CureVac said it had seen the number of requests for its experimental COVID-19 vaccine increase over the past few days, following a halt of the use of Johnson & Johnson's shot amid concerns over rare side effects.

The European Union in November secured up to 405 million doses of CureVac's two-shot vaccine, which has yet to win regulatory approval, the company's only large supply contract so far.

A spokesman said requests have been coming in from various actors, including governments and international organisations but he declined to elaborate. The group is to hold an analyst call on fourth-quarter results at 1400 GMT.

Europe's choppy vaccine rollout hit more trouble this week after J&J suspended shipments of its COVID-19 shot and Denmark said it would drop a similar vaccine from AstraZeneca over very rare cases of blood clotting.