New York, Oct 22 (IANS): Vaccines are being hailed as the solution to the Covid-19 pandemic, but the trials currently underway are not designed to tell us if they will save lives, according to a drug development expert from the prestigious British Medical Journal (BMJ).

Writing in The BMJ medical journal, Associate Editor Peter Doshi, said that several Covid-19 vaccine trials are now in their most advanced (phase 3) stage, but what will it mean exactly when a vaccine is declared "effective"?

Many may assume that successful phase 3 studies will mean we have a proven way of keeping people from getting very sick and dying from Covid-19. And a robust way to interrupt viral transmission.

Yet the current phase 3 trials are not actually set up to prove either, 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," he wrote.

He explained that all ongoing phase 3 trials for which details have been released are evaluating mild, not severe, disease -- and they will be able to report final results once around 150 participants develop symptoms.

In Pfizer and Moderna's trials, for example, individuals with only a cough and positive lab test would bring those trials one event closer to their completion.

Yet Doshi argued that vaccine manufacturers have done little to dispel the notion that the severe Covid-19 was what was being assessed.

Moderna, for example, called hospitalisations a "key secondary endpoint" in statements to the media. But Tal Zaks, Chief Medical Officer at Moderna, told The BMJ that their trial lacks adequate statistical power to assess that endpoint.

Zaks confirmed that Moderna's trial will not demonstrate prevention of hospitalisation because the size and duration of the trial would need to be vastly increased to collect the necessary data.

But Doshi raised another important issue -- that few or perhaps none of the current vaccine trials appear to be designed to find out whether there is a benefit in the elderly, despite their obvious vulnerability to Covid-19.

If the frail elderly is not enrolled into vaccine trials in sufficient numbers to determine whether there is a reduction in cases in this population, "there can be little basis for assuming any benefit against hospitalisation or mortality," he warned.

Doshi said that we still have time to advocate for changes to ensure the ongoing trials address the questions that most need answering.