In 1996, Lone Graff Stensballe and her Danish supervisor Peter Aaby set up camp in Guinea-Bissau, where they believed they had found a groundbreaking link between vaccines and child survival. Their research suggested that live-attenuated vaccines could boost overall health, but whole-cell vaccines were harmful—especially for girls.

Despite WHO investigations and shrugs from other researchers, their work caught fire under the anti-vaccine advocacy of Robert F. Kennedy Jr. In 2023, Aaby and Stensballe’s team proposed updating vaccine testing to account for these 'non-specific effects.' The Trump administration took notice, citing their papers in budget cuts that could cost lives.

However, their methods have been criticized as unorthodox, with Danish scientists calling them biased. Meanwhile, the work continues, funded by the Department of Health and Human Services, raising questions about ethical vaccine trials in impoverished regions.

Aaby and Stensballe’s legacy is complex: while praised for decades of research in Guinea-Bissau, their recent studies have sparked controversy among colleagues who question their findings. Their notion of non-specific vaccine effects has been enough to earn a chapter in the authoritative text on vaccinology, Plotkin's Vaccines.