Pfizer and BioNTech announced on Thursday that they are developing a version of the coronavirus vaccine that targets Delta, a highly contagious variant that has spread to 98 countries. The companies expect to launch clinical trials of the vaccine in August.
The Delta variant, first identified in India, is believed to be about 60 percent more contagious than Alpha, the version of the virus that tore through Britain and much of Europe earlier this year, and perhaps twice as contagious as the original coronavirus. The Delta variant is now driving outbreaks among unvaccinated populations in countries like Malaysia, Portugal, Indonesia and Australia.
Delta is also now the dominant variant in the United States, the Centers for Disease Control and Prevention reported this week.