Diphtheria, once largely controlled in Australia, is making a comeback with outbreaks reported in the Northern Territory and Western Australia. As of March 2026, there have been 17 cases of respiratory diphtheria and 60 cases of cutaneous diphtheria in the Northern Territory. This resurgence is alarming, especially since the disease had been rare since the 1950s due to effective vaccination campaigns. The World Health Organization warns that diphtheria spreads through respiratory droplets and can be fatal, particularly in unvaccinated individuals. In response, India has launched an indigenously manufactured Tetanus and Adult Diphtheria (Td) vaccine to bolster adult immunization and reduce susceptibility to infections. Experts attribute the resurgence to gaps in vaccination coverage and waning immunity among adults. Symptoms include a sore throat, fever, and a characteristic thick grey membrane in the throat. Early treatment with antitoxin and antibiotics is effective, but vaccination remains the best prevention method to avoid outbreaks.