--- title: "A Brazilian City May Have Had Enough COVID-19 Cases to Reach Herd Immunity" description: "Research suggests that the city of Manaus, Brazil may be experience a coronavirus slowdown because enough people got sick to develop herd immunity." date: "2020-09-23" modified: "2020-09-23" authors: - name: "Dan Robitzski" link: "https://futurism.com/authors/danrobitzski" url: "https://futurism.com/neoscope/brazilian-city-covid19-herd-immunity" categories: - "Developments" - "Health & Medicine" tags: - "coronavirus" - "covid19" - "herd immunity" --- # A Brazilian City May Have Had Enough COVID-19 Cases to Reach Herd Immunity ![Research suggests that the city of Manaus, Brazil may be experience a coronavirus slowdown because enough people got sick to develop herd immunity.]() *\Image: Portal da Copa\* Coronavirus cases in the city of Manaus, Brazil are on the decline — and experts suspect it's because so many people already caught COVID-19 there that it's now too hard for the virus to spread to new people. If that's the case, then Manaus would have achieved what's called herd immunity, *[Popular Science ]()*[reports](), which is when so many people in an area build up a resistance or immunity to a disease that even those who didn't get sick are protected as a result. In a [new preprint study](), a team of U.S., U.K., and Brazilian scientists concluded that about 66.1 percent of residents of Manaus were infected with COVID-19 at some point, which falls in line with the percentages that epidemiologists previously predicted would be necessary to establish herd immunity. But because the study hasn't yet been peer-reviewed or formally published — and because other factors like mask-wearing and distancing could contribute to the drop in cases, scientists are still on the fence. "It’s a little difficult to tease out if this is pure herd immunity versus a combination of things," Dr. Thomas Russo, an infectious disease expert at the University of Buffalo who didn't work on the new study, told *PopSci*. "But it's intriguing for sure." It's worth noting that [pursuing herd immunity]() as a pandemic response plan in the U.S. would be devastating, despite [some politicians' insistence]() that it's the correct way forward. Reaching herd immunity in the U.S. would likely come with a national death toll of millions, which is a huge jump from the already-horrific [201,253 lives lost]() in the country. "There will definitely be an excess of deaths and almost certainly an excess of intermediate and long-term health consequences," Russo added. ## Author Dan Robitzki is a senior reporter for Futurism, where he likes to cover AI, tech ethics, and medicine. He spends his extra time fencing and streaming games from Los Angeles, California. ### Author social links [Twitter]()