María Ramírez, a nurse, was the first person in Mexico to get a coronavirus vaccine. “This is the best gift that I could have received in 2020,” she said. Credit...Eduardo Verdugo/Associated Press

Mexico began its coronavirus vaccination campaign on Thursday, becoming the first country in Latin America to do so, and providing a sliver of hope to the population amid a roaring resurgence of the virus.

The head nurse at the Rubén Leñero hospital in Mexico City, María Irene Ramírez, 59, was the first person in the country to get the Pfizer-BioNTech vaccine, as part of the government’s strategy to focus on health care workers in December, January and February before moving on to the older Mexicans considered most at risk.

“This is the best gift that I could have received in 2020,” Ms. Ramírez said during the ceremony, which was broadcast on national television. “We are afraid, but we have to keep going because someone has to face this fight.”

Latin America has become an epicenter of the pandemic, with inequality, a large informal work force, densely packed cities and a fragile health system hindering efforts to stop the spread of the virus and treat the sick.

Countries in the region, led by Brazil and Mexico, racked up some of the world’s highest death tolls as economies crumbled under the weight of lockdowns and government mismanagement.

The first doses of the Pfizer-BioNTech vaccine have also arrived in Costa Rica and Chile, with both countries beginning vaccinationson Thursday. The first 300,000 doses of Russia’s Sputnik V landed in Buenos Aires, in Argentina, on Thursday morning.

The inoculation effort in Mexico is starting as a vicious new wave of the virus has packed hospitals and led authorities to call for a lockdown in the capital, Mexico City, and in three other states. More than 120,000 people have died nationwide, although limited testing means the true count could be much higher.

Medical workers lining up outside a hospital in Mexico City to receive the vaccine on Thursday morning.Credit...Eduardo Verdugo/Associated Press

As of mid-November, some 250,000 more people than expected had died this year, according to official data, an excess mortality rate that suggests a far heavier toll.

With widespread distrust of public institutions, many Mexicans have avoided going to the hospital and instead preferred to be treated, and to die, at home, so that their illness or their cause of death is often not officially recorded as Covid-19.

The country’s response to the outbreak has been widely criticized, with President Andrés Manuel López Obrador refusing to wear a mask in public and continuing to hold public rallies across the country.

Last week, Mexico City authorities increased the capital’s pandemic alert level to red, the highest status, triggering a shut down of all but essential businesses. But the federal government had data that should have prompted an immediate lockdown in early December. Instead, it kept the capital open for an additional two weeks.

Hospitalizations nationwide have reached levels last seen during the first peak of the outbreak in the summer. With 85 percent of beds filled in Mexico City, according to official figures, doctors are begging on social media for residents to stay home.