Dunno what search backend you’re using, but if it’s ElasticSearch this can be done pretty quickly with a Gaussian decay filter. That takes in lat/lng directly,

Dunno what search backend you’re using, but if it’s ElasticSearch this can be done pretty quickly with a Gaussian decay filter. That takes in lat/lng directly, and adjusts the ordering of results. That’d also give the nifty feature of finding the closest available vaccine, even if it’s a hundred miles away (not a walk in the park, but I’d drive that far personally)