The capsule that vanished: How beating Hib unmasked the full Haemophilus influenzae problem

For three decades, the story of Haemophilus influenzae type b (Hib) has been held up as one of modern vaccinology’s cleanest victories. A bacterium that once filled pediatric wards with meningitis and epiglottitis cases was pushed to the margins within a few years of routine infant immunization. But look closely at surveillance data from the past decade, and a more complicated picture emerges. Invasive H. influenzae disease has not disappeared — it has changed shape, changed age group, and changed mechanism. It may well be that what we see now was always there – but it was unmasked only now.  Understanding why requires revisiting an old question in microbiology: what actually makes this organism dangerous, and is the answer still the same one we learned in medical school? A bacterium with two faces Haemophilus influenzae exists in two clinically distinct forms. Encapsulated strains carry one of six polysaccharide capsules, labeled serotypes a...