In areas such as Southeast Asia with a high incidence of mother-to-child transmission of hepatitis B, WHO recommends a birth dose of the vaccine for all children. Hepatitis B vaccine is typically kept refrigerated, within the cold chain. This fact sheet reports on an effort by PATH and Vietnam's National Expanded Program on Immunization to increase coverage rates for the vaccine in Thanh Hoa Province through a new strategy?storing the vaccine outside of the cold chain and using vaccine vial monitors to confirm that the vaccine continued to confer effective protection.