It is not hard to construct a scenario in which Donald Trump’s plans to “Make America Healthy Again” (or MAHA) do the opposite of that. His proposed secretary of health, Robert F. Kennedy junior, is one of the country’s more prominent vaccine sceptics. The man who would be in charge of the Centres for Medicare and Medicaid Services, which provides health coverage for two in five Americans, would be Mehmet Oz, a doctor who has talked about the medical benefits of communicating with the dead and...