Lise Barnéoud is a freelance science journalist who regularly contributes to Le Monde and Mediapart. In addition to Hidden Guests, she is the author of two books about vaccines, Immunisés? and Vaccins. She won the 2008 Fondation Varenne award for science journalism in a national daily newspaper and the Trophées Signatures Santé's 2016 Grand Prix.

Olivia Campbell is a journalist and the New York Times bestselling author of Women in White Coats and Sisters in Science.

J. Lee Nelson, MD, published some of the first scientific studies on microchimerism in the 1990s. She heads the Nelson Lab at the Fred Hutchinson Cancer Center in Seattle, where her team investigates the health consequences of microchimerism.

Bronwyn Haslam is a Montreal-based translator with degrees in modern literature and languages and in cellular, molecular, and microbial biology. With Aleshia Jensen, she was a finalist for the 2022 Governor General's Literary Award for Translation and the 2023 Cole Foundation Prize for their translation of Mirion Malle's This Is How I Disappear.