September 29. South America, exceptionally hard-hit by Covid-19, is seeing a sudden drop in cases and deaths, apparently from rapid and thorough vaccines on the heels of a horrific wave that provided antibodies to those it didn’t kill.
Over a seven-day period, the continent now makes up 6% of cases and 9% of deaths, the lowest since the start of the pandemic. At its peak in June, it represented 38% of global infections and 44% of fatalities.
One peculiarity of the continent is that the delta variant upending plans from Asia to the U.S. hasn’t found traction there. It had similarly contagious mutations, known as gamma and lambda, and their presence may be keeping delta at bay and extending immunity. This is distinct from Mexico, Central America and Cuba, where delta has taken hold and the other two hadn’t.
“Vaccination occurred in an environment where there had already been a high level of transmission,” said Lyda Osorio, an epidemiologist at Universidad del Valle’s school of public health in Cali, Colombia. “So a hypothesis that one could anticipate is that the vaccines became that ‘booster’ for people who had already been infected, and that immunity may last a little longer.”
South America has 1.15 million of the 4.75 million officially registered deaths during the pandemic, 24% of the total, despite only having 6% of the world’s population. Even accounting for severe under reporting, nearly 10% of the population has tested positive.