Factbox: COVID-19 vaccine frontrunners

AstraZeneca Plc said on Monday its vaccine for the novel coronavirus developed by Oxford University could be around 90% effective without any serious side effects.

The effectiveness of the vaccine depended on the dosing, and fell to just 62% when given as two full doses rather than a half-dose followed by a full dose at least one month apart.

The data follows positive results from Pfizer Inc, Moderna Inc and Russia's Sputnik V. Pfizer said last week it will apply to U.S. health regulators for emergency use authorization (EUA) of its COVID-19 vaccine.

More than 150 potential vaccines are being developed and tested globally to stop the COVID-19 pandemic, with 48 in human trials, according to the World Health Organization (WHO).