Doctors fear the return of Haemophilus influenzae type b (Hib), a bacterial infection that can be disabling and sometimes fatal in children.[1] This return is related to the increasing hesitancy of vaccination.[3] Before the introduction of the vaccine, about 20,000 cases of invasive Hib disease occurred annually in the US, a number that has declined by 99% since its widespread use.[3][6] The Hib vaccine reduced not only the risk of disease, but also colonization in the throat, thus limiting spread in the community even in the unvaccinated.[3] Vaccination rates above 90% in infants and toddlers are required to maintain herd immunity.[3] In the US today, Hib is rare, with fewer than 50 cases per year, but declining vaccination rates increase the risk to children.[3] In Calgary, 8 Hib cases were reported in 2025 compared to 3 in 2024 and only 2 between 2019–2023.[2] Complications of Hib meningitis include blindness, deafness, mental retardation, and death, with a mortality rate of about 5%.[1]