This document provides a landscape of 5-dose vial measles-containing vaccine (MCV) use in Southeast Asia and the Western Pacific. - The 13th meeting of Southeast Asia’s Regional Immunization Technical Advisory Group (RITAG), held in August 2022, recommended that “countries that are yet to switch from 10-dose to 5-dose measles-rubella (MR) vials review the local context related to suggested indicators and plan for switching to enhance coverage and reduce wastage. Sensitization will be required for healthcare workers (HCWs) around the 5-dose vial prior to the switching.” In issuing this recommendation, the Southeast Asia Region (SEAR) RITAG now joins Africa’s RITAG, which made a similar recommendation in 2020 - As of November 2022, only three out of 11 countries in SEAR are still using 10-dose vials, and one more country (Nepal) is expected to switch to 5-dose vials in 2023 - In the Western Pacific Region, most countries are using MCV 5-dose vials or smaller for routine immunization (RI)