If WHO guidelines were adopted only in the United States (1 of at least 21 countries described here that implement adult booster vaccinations), the risk-to-benefit ratio of immunization would improve due to a concomitant decrease in vaccine-associated adverse events, including a reduction of approximately 13,200 medically attended local vaccine site reactions, approximately 800 cases of cellulitis, and up to 73 cases of ulcerated lesions that would be anticipated to occur when 15.2 million adult vaccinations are administered annually in the US...removing the recommendation of decennial adult booster vaccination would save approximately $1.03 billion annually in healthcare costs in the United States alone...It is possible that these cost savings could then be used to target vaccination programs to vulnerable populations of unvaccinated/undervaccinated people who currently account for the majority of tetanus and diphtheria cases