A fast-tracked vaccine might not be the holy grail to quickly end the pandemic and may cause harm, a group of top scientists have warned.

There are more than 200 candidates in various stages of development, with some hope that the first vaccines could be ready as soon as six months.

But scientists have warned that “the history of vaccine development is littered with candidates that have failed at this late stage”.

“There is no guarantee that these vaccines will be effective,” warns the report compiled by the Royal Society.

“If vaccines were deployed outside clinical trials before safety and efficacy have been fully established and prove to be ineffective or cause rare but severe side effects during the larger-scale roll-out, they could cause substantial harm and damage public confidence in other vaccines.

“Strict regulation of clinical trials and robust licensing rules must therefore be maintained in spite of the urgency and requirement for speedy implementation.”

US President Donald Trump claimed during this week’s presidential debate that a vaccine could be “weeks away”, despite public health experts indicating mid-2021.

Mr Trump during the first presidential debate against Democratic presidential nominee Joe Biden. Photo: Getty

The Royal Society report says a vaccine could be six months away but warns of the importance of ensuring it it safe, effective and does not erode public trust.

“The first generation of vaccines for SARS-CoV-2 may be available within the next 6-18 months,” the report states.

“However, these may be suboptimal.

“The first vaccines that are licenced for use against COVID-19 are likely to significantly influence the public perception and debate.

“There is a risk that a vaccine that is poorly effective or reactogenic, or which requires multiple booster injections will not create an incentive for uptake among those who perceive themselves at low risk, and if the vaccine is perceived as having been rushed through safety testing, this might create long term distrust and hesitancy.”

Clinical development of early vaccine candidates has been “accelerated to an unprecedented level” as the pandemic death toll passed one million, the report said.

The Oxford, Moderna and Sinovac vaccines are among those that have started large-scale field trials internationally.

Scott Morrison at AstraZeneca’s Sydney labs to promote the government’s vaccine deal. Photo: AAP

The report said the race to make a vaccine was being pursued with “cost not being a major consideration”.

“However as time progresses governments will want a cost effective vaccine,” it states.

“To date Moderna are thought to be targeting USD 25 to USD 30 per dose ($35 to $41), Biontec/Pfizer USD 19.50 per dose ($27) and AstraZeneca a few dollars per dose.

“To use the Moderna vaccine for one cycle of vaccinations in the UK would cost about USD 3.4-4 billion ($4.7 billion to $5.57 billion) just for the vaccine.

“Even a few dollars a dose will be out of reach for much of the world’s population.”

Scientists said the world should work together “in the long term interests of sustaining international travel and trade”.

“Cooperation between nations to invest in vaccine development, manufacture and purchase will increase the chances of successful development and availability,” it said.

“Furthermore, allocation of vaccine doses, once available, to all nations collaboratively is likely to save more lives than unequal allocation of the same number of doses to a limited number of nations.”