Epicene "They" Spreads to Science and Medical Writing

Even writing in medical journals, often seen as being very formal academic-speak, is now using singular "they," also referred to as "epicene 'they.' "

You can find evidence of this in section 11.12.2 of the new 11th edition of the AMA Manual of Style:

Avoid sex-specific pronouns in cases in which sex specificity is irrelevant. Do not use common-gender "pronouns" (eg, "s/he," "shem," "shim"). Reword the sentence to use a singular or plural non–sex-specific pronoun, neutral noun equivalent, or change of voice; or use "he or she" ("him or her," "his or her[s]," "they or their[s]"). The use of the "singular they" construction is permitted when rewriting would be awkward or unclear (see 7.2.3.2, Pronoun-Pronoun Agreement).

The post "Singular They" on the AMA Style Insider blog talked about this before the manual's 11th edition was published:

The AMA Manual of Style will follow suit [ie, follow the lead of the AP Stylebook and the Chicago Manual of Style] with the next edition, allowing the use of plural pronouns with singular indefinite antecedents (eg, Everyone allocates their time) in an effort to avoid sex-specific pronouns and awkward sentence structure.

If you are a paying member of the Council of Science Editors, you can read more about the history of epicine "they" in the article "The Epicene Solution" in the spring 2020 issue (volume 43, issue 1) of the journal Science Editor.