I turn 40 today, and I was planning to have a party. The Delta surge made me nervous about it. The arrival of Omicron made me cancel it. The plan was to have an extended house party, with a couple dozen people popping by over the weekend. On the one hand, it would have been an unmasked, indoor event—the kind in which the coronavirus, in all its incarnations, spreads most easily. On the other hand, everyone who was going to be there is fully vaccinated, and most of them, myself included, have been boosted. A month ago, I would have...