The World Health Organization (WHO) issued interim recommendations on Thursday for mixing and matching COVID-19 vaccines from different manufacturers for both the second dose and booster shots.

Depending on availability, mRNA vaccines, such as those developed by Pfizer Inc and Moderna Inc, can be used as subsequent doses after initial doses of AstraZeneca's vectored vaccine and vice versa, the global health body said.

AstraZeneca and any of the mRNA vaccines can also be used after initial doses of Sinopharm or Sinovac's inactivated vaccines, the WHO said.