The P.1 coronavirus variant first identified in Brazil may be twice as transmissible as previous strains and may elude up to nearly half of the immune defenses built up during previous infections, a new study suggests.
According to data collected in Manaus, Brazil, P.1 probably emerged in mid-November 2020 in the city, researchers report on April 14 in Science. The variant quickly took center stage there and spread to the rest of Brazil and at least 37 other countries, including the United States.
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Previous examinations of the genetic composition of the variant have shown that P.1 contains many differences from the previous strains, including 10 amino acid changes in the ear protein, which helps the virus infect cells. Three of these ear protein changes are worrisome because they are the same mutations that allow other worrisome variants to bind more firmly to human proteins or evade antibodies (SN: 2/5/21). Simulations of the P.1 properties suggest that the variant is 1.7 to 2.4 times more transmissible than the previous SARS-CoV-2 strain. It is unclear whether this increase in transmissibility is due to people producing more of the virus or having longer-term infections.
Some studies have suggested that people who previously had COVID-19 may become infected with P.1. The new study suggests that people who have had previous infections have between 54 and 79 percent protection against P.1 as they do against other local strains. That partial immunity can leave people vulnerable to reinfection with the variant.
It is unclear whether the virus makes people sick or more deadly than other strains. The researchers estimated that coronavirus infections were 1.2 to 1.9 times more likely to cause death after P.1 arose than before. But Manaus ’health care system has been under stress, so the increase in deaths may be due to overcrowded hospitals.
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