Brazil's health officials say more than 4 million children still need to be vaccinated against measles.
More than 1,380 people have been infected in an outbreak linked to cases imported from Venezuela.
To stop the disease's spread, Brazil's Health Ministry launched a campaign this month to vaccinate all children between 1 and 5 — regardless of their vaccination history. It said Friday that 4.1 million children still had not been vaccinated as the campaign enters its final week.
Among the places with the lowest vaccination rates is Roraima, one of two border states with Venezuela where cases are concentrated.
Health services in the neighboring country have collapsed amid economic and political turmoil, which has caused more than 1 million people to flee.
Tens of thousands have migrated to Brazil.