Scientists around the world are scrambling to find a vaccine — the ultimate Covid-19 panacea. There are now 70 candidate vaccines in development, up from to 44 on March 20, according to a document from WHO published Saturday. Experts expect it to take between 12 and 18 months to get a vaccine approved for mass use. Of the 70 Covid-19 vaccines in development, only three are currently in clinical trials, meaning they are being tested on humans. Clinical trials are designed to assess the safety and efficacy of a new drug and consist of several phases, each involving more patients. China's CanSino Biological, in partnership with the Beijing Institute of Biotechnology, is in the lead, with the only candidate vaccine currently in phase two trials. U.S. players Moderna and Inovio Pharmaceuticals are the other two developers testing vaccines on humans and both are currently in phase one. The remaining 67 potential vaccines are still only in the pre-clinical trial stage.

Hopes pinned on existing drugs

To bridge the gap between now and then — when a vaccine is approved — scientists continue to search for effective treatments, with efforts focused on several existing drugs. British health-care giant AstraZeneca has joined this effort, announcing today that it would start a clinical trial to assess the potential of Calquence, a drug already approved for the treatment of leukaemia, in the treatment of the immune response associated with Covid-19. The trial is expected to open for enrolment in the coming days in the U.S. and several countries in Europe.

An Israeli scientist works at a laboratory at the MIGAL Research Institute in Kiryat Shmona in the upper Galilee in northern Israel on March 1, 2020 where efforts are underway to produce a vaccine against the COVID-19 coronavirus adapted from another for infectious bronchitis virus. Jalaa Marey | AFP | Getty Images