The spread of vaccine misinformation may contribute to vaccine refusal/hesitancy and consequent harms. Nonetheless, censorship is often rejected on the grounds of free expression. This article examines John Stuart Mill’s influential defence of free expression but finds that his arguments for freedom apply only to normal, reasonably favourable circumstances. In other cases, it may be permissible to restrict freedom, including freedom of speech. Thus, while Mill would ordinarily defend the right to express false views, such as that vaccines cause autism, (...) he might have accepted restrictions on anti-vaccine misinformation during the present pandemic. This illustrates that even the staunchest defenders of free speech can permit temporary restrictions in exceptional circumstances. (shrink)