The head of the World Health Organization (WHO) has said that while there is hope for a vaccine against Covid-19, one might never be found.
Tedros Adhanom Ghebreyesus told a news briefing there was "no silver bullet at the moment - and there might never be".
Mr Tedros implored people around the world to comply with measures such as social distancing, hand-washing and mask-wearing, saying: "Do it all."
Globally, more than 18 million Covid-19 infections have been recorded.
The death toll stands at 689,000, with both figures given by the US-based Johns Hopkins University.
Speaking from its headquarters in Geneva, the WHO chief said work on immunisation was progressing.
Meanwhile, the first stage of a WHO investigation into the possible source of the outbreak in China is now complete, he said.
Infectious disease experts believe the virus initially jumped from animals to humans and attention has focused on a wet market in the Chinese city of Wuhan, where the Covid-19 pandemic began.
