In this scenario, vaccine skepticism, actual problems with the doses, unforeseen side effects, human error in the logistics of transporting the vaccine, or distribution issues—wasted doses from problems with Pfizer’s required ultra-cold storage, for example—hamper the effort to achieve anything close to herd immunity. Many people don’t get the vaccine until after next year.

One possibility is that “we have so many mutations that the vaccine stops working” in that scenario, said Monto. To be clear, the consensus among experts—including Monto—is that such a situation is very unlikely.

Then, the lower-income countries that were already slated to see the vaccine as late as 2024, per Horney, would take even longer to get their share of the global supply. Community transmission, in this case, would not be controlled the way that it was anticipated to be by the summer, and when cold weather returns in the fall, things still don’t look pre-pandemic “normal.”

In fact, deaths and cases could explode once again.