Mexican President Andrés Manuel López Obrador said he has tested positive for covid-19. Announcing the news, López Obrador said his symptoms are mild and he's already started receiving medical treatment. "As always, I am optimistic," he wrote. The development comes as Mexico grapples with an upsurge in infections, with deaths nearing 150,000.Obrador says he will continue working from home, including speaking to President Vladimir Putin about acquiring a Russian-made vaccine. He has long been criticized for repeatedly dismissing the health risks of the virus.