The World Health Organization (WHO) chief on Monday said although a number of vaccines are now in phase three clinical trials, there is no "silver bullet" at the moment, and there might never be for Covid-19.

WHO Director-General Tedros Adhanom Ghebreyesus told a virtual press conference that for now, stopping Covid-19 outbreaks come down to the basics of public health and disease control, including testing, isolating and treating patients, and tracing and quarantining their contacts, Xinhua reported.