The scientist in charge of France’s vaccine rollout, Alain Fischer, must sometimes feel like Sisyphus forever rolling his boulder up the hill. After months of patiently working to win over a doubting public’s acceptance of the groundbreaking mRNA vaccines from Pfizer Inc. and Moderna Inc., he’s now fighting to convince French doctors to offer AstraZeneca Plc’s more traditional shot to their patients.

Resistance runs deep even as doses pile up, more data about efficacy emerges and President Emmanuel Macron, along with other European Union leaders, frantically tries to speed up inoculations.

The challenge isn’t dispelling kooky theories about vaccination’s side effects or effectiveness, but the more complex informed skepticism that leads to damaging "comparison shopping.” One doctor took to social media to criticize AstraZeneca’s less spectacular clinical efficacy levels of 62% compared to Pfizer and Moderna’s 95%, and its apparent weakness against variants, and said he’d "wait” before offering it.