LONDON (AP) — Regulators in the U.K. and four other countries plan to fast-track the development of modified COVID-19 vaccines to ensure that drugmakers are able to move swiftly in targeting emerging variants of the disease.

Previously authorized 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.

The new guidance was issued jointly by regulators in the U.K., Australia, Canada, Singapore and Switzerland. The guidelines build on the model already used to modify the flu vaccine in response to continual changes in that virus.

Under the new rules, developers will be required to provide “robust evidence” that modified COVID-19 vaccines produce a strong immune response to the variant, as well as data showing 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,” Dr. Christian Schneider, the MHRA’s chief scientific officer said in a statement. “Should any modifications to authorized COVID-19 vaccines be necessary, this regulatory approach should do that.”

The announcement comes amid concerns that a variant first discovered in Brazil may be more resistant to existing vaccines than other variants. The U.K. has banned direct flights from 33 countries in an effort to prevent variants of concern from becoming established in Britain.