Similar to NYC, San Francisco will require proof of full vaccination against COVID-19 for indoor activities like eating at restaurants, going to bars, and going to the gym.
According to the San Francisco Chronicle, this will officially take effect starting Monday.
It appears that San Francisco's guidelines are even more strict than those in New York City. For example, SF will require you to be FULLY vaccinated and show proof whereas NYC only requires proof of at least one short to participate in indoor activities.
To help prevent fake cards from being used or help those who have misplaced their vaccination cards, they've established an online database with a bar code that vaccinated people can use to prove their status.