Scientists say trials being carried out by the world’s leading pharmaceutical companies are not powerful enough to guarantee the jab will save lives

Doctor preparing the coronavirus COVID-19 vaccine

An ‘effective’ Covid-19 vaccine will still not stop people from getting sick and dying, scientists have warned.

They say trials being carried out by the world’s leading pharmaceutical companies are not powerful enough to guarantee the jab will save lives.

Several vaccines have entered the most advanced stage of testing – known as ‘phase three’ – and could be declared effective in the near future.

But the trials are only investigating mild cases and not whether it will help the most vulnerable, according to a report by the British Medical Journal (BMJ).

BMJ associate editor Dr Peter Doshi said: “None of the trials currently underway are designed to detect a reduction in any serious outcome such as hospitalisations, intensive care use, or deaths.

“Nor are the vaccines being studied to determine whether they can interrupt transmission of the virus.”