Developing a vaccine against the coronavirus could take "years", Germany's health minister Jens Spahn said on ARD television.
"I would be delighted if it was possible to achieve this in a few months. But it can also take years as there can of course be setbacks, as we have seen some with other vaccines. The development of vaccines is one of the most challenging and difficult tasks in medicine," Spahn said.
The minister's comment contradicts the more positive outlook voiced by President Trump on Sunday, who believes that the vaccine will be ready by the end of this year.
UN Secretary-General Antonio Guterres previously stated that as soon as such a vaccine is developed, it should be universal and available for every individual throughout the world.
According to the World Health Organisation, there are eight candidate vaccines in clinical evaluation, with another 94 in preclinical evaluation.
The new coronavirus that emerged nearly four months ago in China has spread across the globe and infected a whopping 3,356,205 people. Some 238,730 people fell victims of COVID-19, the WHO said in its latest update posted on Monday at 10:00 a.m. CEST.