MEXICO CITY — Mexico is on the verge of approving the Russian COVID-19 vaccine Sputnik V following the publication of early results of an advanced study.

Assistant Health Secretary Hugo López-Gatell, the government’s pandemic spokesman, says the health ministry signed a contract Monday for 400,000 doses of Sputnik V that will arrive this month.

Once approved, the Russian vaccine would become the third to receive emergency approval in Mexico. The regulating agency approved the Pfizer vaccine in December and AstraZeneca’s in January. Mexico turned to the Russian vaccine following delays in obtaining others it was counting on.

Mexico has so far given about 675,000 doses, all Pfizer, to a population of 126 million. On Tuesday, a second batch of the active substance in the AstraZeneca vaccine arrived in Mexico, where it will be packed and distributed through the rest of Latin America.

The Mexican government also launched a new website Tuesday for people over age 60 to register for vaccination appointments. However, the Mexican Health Department’s website was quickly overwhelmed and not working.