By Anthony Boadle
https://www.reuters.com/journalists/anthony-boadle
The largest city in Brazil’s Amazon has closed bars and river beaches to contain a fresh surge of coronavirus cases, a trend that may dash theories that Manaus was one of the world’s first places to reach collective, or herd, immunity.
When a large portion of a community becomes immune to a disease, its spread becomes unlikely.
University of Sao Paulo researchers suggested that a drastic fall in COVID-19 deaths in Manaus pointed to collective immunity at work, but they also believe that antibodies to the disease after infection may not last more than a few months.
Local authorities on Friday enforced a 30-day ban on parties and other gatherings, and restricted restaurant and shopping hours, a setback for the city of 1.8 million after the worst of the pandemic seemed to be behind them.
In April and May, so many Manaus residents were dying from COVID-19 that its hospitals collapsed and cemeteries could not dig graves fast enough. The city never imposed a full lockdown. Non-essential businesses were closed but many simply ignored social distancing guidelines.
Then in June, deaths unexpectedly plummeted. Public health experts wondered whether so many residents had caught the virus that it had run out of new people to infect.
Research posted last week to medRxiv, a website distributing unpublished papers on health science, estimated that 44% to 66% of the Manaus population was infected between the peak in mid-May and August.
https://www.reuters.com/article/us-health-coronavirus-brazil-manaus/in-brazils-amazon-a-covid-19-resurgence-dashes-herd-immunity-hopes-idUSKBN26I0I4