Omicron didn’t much shift the way I weighed my personal risk. Although the new variant can evade some of our immune defenses, early data suggest that boosted people are roughly as protected against Omicron infection as people with two vaccine doses are against Delta. That protection isn’t foolproof, but even if immune systems can’t block the virus from gaining an initial foothold, they should still be able to stop it from causing too much damage. If I got the virus on my birthday, I’d expect to be knocked down for a time but okay by Christmas—and I’d expect the same to be true for everyone who was meant to come.

I don’t know the odds that this would happen. But I know that said odds are rising with every passing day, given how quickly and easily Omicron is spreading, even among highly vaccinated populations. I know that many of my friends, like many vaccinated Americans, have been going out to restaurants, bars, gyms, and movie theaters. I know that Omicron’s incubation period—the gap between infection and symptoms—seems unusually short, so that even people who tested negative a few days ago might still be infected and infectious. I know that even mild infections can lead to long COVID.

If someone got sick, I know others could too. A week later, many of my friends will spend Christmas with their own families. At best, a cluster of infections at the birthday party would derail those plans, creating days of anxious quarantine or isolation, and forcing the people I love to spend time away from their loved ones.