When Americans divide themselves into camps, they stick to them fiercely: Democrats versus Republicans, pro-life versus pro-choice, gun rights versus gun control. Add to that, as has become apparent over the course of the past year, those who are pro- versus anti-coronavirus vaccines. As with so many other polarizing issues, your position on getting or not getting inoculated against COVID-19 has become more than a medical question. It’s morphed into a form of cultural identifier, a sign of your membership in one tribe or another.
More than ever, that’s becoming clear as booster shots are rolled out around the nation, with about 70 million Americans now eligible for an additional dose and tens of millions more set to join them as the eligibility age inevitably falls. The extra dose comes as very good news to a lot of the population—people who are mindful of the way vaccine-induced antibody levels fall over time and anxious to bump them back up. But that doesn’t remotely include everybody, with resistance to even initial vaccinations keeping the country far from the much hoped-for herd immunity.
All of this is playing out as the government looks beyond first doses and encourages Americans to step up for their extra dose. Plenty of people are responding. According to data from the U.S. Centers for Disease Control and Prevention (CDC), booster rates are now exceeding first-shot rates across the country. In the week ending October 24, just over 400,000 people per day were getting boosters, compared to just over 200,000 receiving their first shots.
Those numbers have been moving in a sort of Newtonian, equal-and-opposite dance since late August, when more than 400,000 people daily were getting first doses and boosters were just being rolled out to the immunocompromised. The lines crossed in late September, when the CDC recommended Pfizer-BioNTech boosters for at-risk groups, and the upward trend for boosters and downward trend for first shots has continued since. Boosters got another bump on October 21, when the CDC approved additional doses of the Moderna and J&J vaccines.
Those recommendations, CDC director Rochelle Walensky said in a statement last week, “are another example of our fundamental commitment to protect as many people as possible from COVID-19.” When it comes to the boosters, the government’s pro-vaccine message is apparently being heard. When it comes to first doses, not so much.
This story was adapted from The Coronavirus Brief, TIME’s daily COVID-19 newsletter. Sign up here.