The UK, Australia, Canada, Singapore and Switzerland plan to fast-track the approval of vaccines against new coronavirus variants.
The aim is to get modified versions of COVID-19 shots approved more swiftly, as flu jabs are every year.
The announcement comes amid concerns that a variant first discovered in Brazil may be more resistant to existing vaccines than other variants.
Previously authorised vaccines that are modified to target new variants "will not need a brand new approval or 'lengthy' clinical studies,'' Britain's Medicines and Healthcare Products Regulatory Agency said in a statement.
Under the new rules, companies developing the modified vaccines will be required to provide "robust evidence" that the jabs produce a strong immune response to a given variant, as well as data showing that they are safe and meet quality standards.
"Our priority is to get effective vaccines to the public in as short a time as possible, without compromising on safety," the MHRA's chief scientific officer Dr Christian Schneider, said in a statement.