President Joe Biden’s announcement Thursday that broadly expanded mandatory COVID-19 vaccinations or at least compulsory weekly testing is a sign, possibly, that the administration sees the writing on the wall.

Even with tentative but promising signs that the fourth wave of surging cases in COVID-19 in the United States, dating back to the first days of summer, was waning, without drastic measures, the fifth will be catastrophically worse.

The new requirements are estimated to affect about 100 million people, including most federal workers and a substantial number of private sector employees—many of whom are already vaccinated.

This would largely affect working-age residents (age 18-64), who currently number above 200 million, of whom 59.8% are vaccinated, according to TIME’s analysis of daily figures from the U.S. Centers for Disease Control and Prevention.