The anti-vaxxine movement genesis is in San Marin county in San FransiscoMarin county, not San Marin county, and it's just to the north of SF in the Bay Area. Marin County is basically rich people and rich hippies. It is an origin point on the anti-vaccination movement, going back to well before COVID (a 'movement' I strongly consider to be astroturfed:https://pubmed.ncbi.nlm.nih.gov/30138075/).
San Francisco (like everywhere) procrastinated on responding to COVID but then reversed course and shut down pretty early. It was strongly anti-Trump, to be sure, but vaccines weren't available during the Trump administration and the doubts were primarily directed at the administration's claims and policies. When the topic of vaccines came up during the Presidential campaign, VP candidate Kamala Harris (also from the Bay Area) did not express skepticism about vaccines per se but said she would base her judgement on assessments by scientists rather than those coming from the administration itself.
Expressing doubt was understandable given Trump's many flippant or outright goofy statements on COVID & its treatment, from asserting that the disease would have petered out by Easter (of 2020) to ruminating on whether it might be treatable with ultraviolet lights and some sort of aerosolized disinfectant to 'do a cleanse' on the lungs. US public health messaging during CVOID was poor across the board, but that coming out of the incumbent administration was particularly bad and in my view opened the door to all kinds of quackery, eg: https://globalnews.ca/news/7229174/coronavirus-demon-sperm-d...