MEXICO CITY (AP) — Once Mexico has vaccinated its frontline medical workers against COVID-19, the government will turn its attention to the elderly living in its most remote places, President Andrés Manuel López Obrador said Tuesday.

Ten thousand brigades made up of medical personnel and health promoters with security provided by the National Guard will target 3 million senior citizens in rural areas. The brigades will work back from isolated areas to towns and cities.

The plan will hinge on Mexico’s approval of the Chinese CanSino vaccine, which only requires a single dose. So far, Mexico has approved only vaccines from Pfizer and AstraZeneca.

Mexico started deploying those vaccines in December in Mexico City and the northern state of Coahuila. The government hopes to have 750,000 health workers vaccinated by the end of January.

“We’re going to start at the bottom, where the most marginalized people live,” López Obrador said of a population that makes up an important part of his political base.

The president said teachers in states where it could be possible to return to in-person classes would also be vaccinated at that time.

Much will depend, though, on the availability of the vaccines. CanSino has not yet presented the results of its final stage trials, which would be needed for emergency approval.