I came across sth in the news a few days ago with Pfizer saying the immune protection elicited by their vaccine seems strong even after 6 months. Those who’ve got Covid and recovered seem to hv immunity for about 8 months. All these are areas still under study though.
https://www.nytimes.com/2021/03/27/world/americas/virus-brazil-bolsonaro.html
Yesterday the no. of daily deaths due to Covid surpassed 4,000, the highest since the pandemic began.
https://news.yahoo.com/covid-brazil-more-4-000-020252274.html