Coronavirus | Challenges in developing, testing vaccines against variants Updated: Updated: February 20, 2021 21:33 IST It is highly unlikely that we will be repeating phase-3 studies for every new vaccine based on a variant strain, but we do need alternative regulatory pathways, says Gagandeep Kang. Share Article It is highly unlikely that we will be repeating phase-3 studies for every new vaccine based on a variant strain, but we do need alternative regulatory pathways, says Gagandeep Kang. With the emergence of three variants — B.1.1.7 first found in Britain, B.1.1.248 first seen in Brazil, and B.1.351 first detected in South Africa — less than two months after the first COVID-19 vaccine was approved for emergency use by the U.S. FDA, all companies have begun making booster shots or tweaking the existing vaccine based on the new variants.