New models suggest that if vaccination rates only reach 68 percent and people refuse to wear masks, this autumn could be dangerous—particularly given the spread of the highly infectious delta variant.

Covid-19 cases across the United States have finally started dropping. People are venturing outside again to host barbecues and birthday parties. This week, both New York and California officially lifted restrictions that have been in place since last year to help defend against Covid-19. It feels like the worst of the pandemic could be behind us.

If this all sounds familiar, it’s because something similar happened last year. In early summer, cases fell dramatically, and they stayed low in some states. But they soon shot up across the Sun Belt, where 35,000 people died last summer alone, and then the virus exploded across the country in the fall and winter.

The enormous difference from last year is that we now have incredibly safe, effective vaccines. But in areas across the country with persistently low vaccination rates, we could see a repeat of last summer’s unexpected surge. And this year, we have the much more transmissible delta variant to reckon with. The pandemic isn’t over: Worldwide, it has already killed more people in 2021 than it did in all of 2020. The safety gap between the vaccinated and the unvaccinated is widening. Read more at The New Republic.