COVID-19 vaccine after less than two months of human testing prompted alarm among global health experts, who said that with no full trial data, the vaccine is hard to trust.Intent on being first in the global race to develop a vaccine against the pandemic disease, Russia has yet to conduct large-scale trials of the shot that would produce data to show whether it works - something immunologists and infectious disease experts say could be a "reckless" step."Russia is essentially conducting a large population level experiment," said Ayfer Ali, a specialist in drug research at Britain's Warwick Business School.She said such a super-fast approval could mean that potential adverse effects of a vaccine may not be picked up.