Mexican President Andrés Manuel López Obrador said he has tested positive for COVID-19.

His symptoms are mild and he's already started receiving medical treatment, he said in a tweet announcing the news on Sunday evening.

"As always, I am optimistic," he wrote. "We will all move forward."

López Obrador has resisted lockdowns and repeatedly dismissed the health risks of the virus.

"Pandemics won't do anything to us," he asserted in March. In late July, as the country crossed 46,000 deaths due to the coronavirus, the president told reporters he wouldn't wear a mask until Mexico had eliminated corruption: "Then I'll put on a mask and I'll stop talking."

Mexico is approaching 150,000 coronavirus-related deaths — the world's fourth largest death toll — with over 1.75 million cases, according to Johns Hopkins University. With little testing done, the actual case numbers are likely far higher, according to health officials.

López Obrador was elected in 2018, lifted by a large base of wide-working class supporters, after campaigning on the fight against domestic corruption and violence. Now, between Mexico's deepening economic recession and the pandemic, the country's poorest citizens are bearing the brunt of dueling crises.

In December, Mexico became the first Latin American country to kick off a vaccination effort upon receiving an initial batch of the Pfizer-BioNTech vaccine. Mexico has administered more than 600,000 doses so far.

López Obrador plans to speak with Russian President Vladimir Putin on Monday, he said on Twitter, to discuss Mexico's acquisition of the Russia's Sputnik V COVID-19 vaccine.

"Regardless of friendly relations," he wrote in Spanish, "there is a possibility that they will send us the Sputnik V vaccine."

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