Mexico approved the Oxford-AstraZeneca vaccine for emergency use.

Mexico approved the Oxford-AstraZeneca coronavirus vaccine for emergency use on Monday, the country’s top epidemiologist, Hugo López-Gatell, announced in a tweet on Monday evening. It is the fourth country to approve the vaccine.

Mexico’s foreign secretary, Marcelo Ebrard, had previously said the approval was “imminent.”

Mr. Ebrard celebrated the approval on Monday evening as “very good news,” tweeting that it would allow the country to start production “very soon.” AstraZeneca said in August it would work with the Mexican and Argentine governments to produce 150 million initial doses for distribution across Latin America, and later produce at least 400 million doses for the region.

Last week, Britain became the first country to grant emergency approval for the Oxford-AstraZeneca vaccine. Argentina soon followed suit. India on Sunday said it had also approved the Oxford-AstraZeneca vaccine.

On Monday, an 82-year-old dialysis patient in Oxford was the first person in the world to receive the clinically authorized, fully tested Oxford-AstraZeneca vaccine when Britain began administering the vaccine.

The Oxford-AstraZeneca shot is poised to become the world’s dominant form of inoculation. At $3 to $4 a dose, it is a fraction of the cost of some other vaccines.

And it can be shipped and stored in normal refrigerators for six months, rather than in the ultracold freezers required by the Pfizer-BioNTech and Moderna vaccines, making it easier to administer in poorer and harder-to-reach areas.

Mr. López-Gatell said he had incorrectly reported that a single-dose vaccine that had undergone phase three trials in Mexico by Chinese-Canadian firm CanSino was approved, according to The Associated Press.

The United States and the European Union have indicated that they are unlikely to authorize the Oxford-AstraZeneca vaccine until at least February.

When given in two full-strength doses, the regimen authorized by Britain, AstraZeneca’s vaccine showed 62 percent efficacy in clinical trials — considerably lower than the roughly 95 percent efficacy achieved by Pfizer and Moderna’s shots. No one who received the vaccine in the clinical trials developed severe Covid-19 or was hospitalized.

Much of the world is looking to AstraZeneca in part because it has set more ambitious manufacturing targets than other Western vaccine makers. It has said that it expects to make up to three billion doses this year — a haul that, at two doses per person, would be enough to inoculate nearly one in five people worldwide. The company has pledged to make the vaccine available at cost around the world until at least July 2021, and in poorer countries into perpetuity.

Mexico has the fourth-highest number of coronavirus deaths in the world, according to a New York Times database, and the 13th-highest number of coronavirus cases.

The country has reported nearly 1.5 million infections, and 127,213 Mexicans have died of the virus.

But Mexico’s transparency with the severity of the virus in the country has been spotty. Last month, federal officials told the public that the number of cases in the capital, Mexico City, had not reached a level requiring — per its own standards — a lockdown. A New York Times analysis using the government’s own official numbers found that the city had surpassed that level.

In the spring, The Times reported that the federal government was not reporting hundreds and potentially thousands of coronavirus deaths in the capital.