Chen Xi, assistant professor of health policy and economics at the Yale School of Public Health, explains why the pandemic is so severe in Brazil. "One of the most important reasons is the new variant, which is believed to be twice transmissible than before. The slow vaccination campaign so far is also worrisome. Brazil, according to our estimates and estimates from our colleagues, will still not have enough doses of vaccines to vaccinate 50 percent of the population by the end of 2021. All the countries in the southern hemisphere have to rush up before the winter," he said.