In an article published in U.S. News & World Report, experts revealed that the mpox vaccine’s protective effects may wane quickly—even among patients who have received two doses. In a study presented at the European Congress of Clinical Microbiology and Infectious Diseases 2024, researchers discovered that in most patients who received two mpox vaccines but no smallpox vaccines, antibody levels diminished to undetectable levels within 28 days of the second vaccination. One such patient experienced a breakthrough mpox infection 2 years after receiving two doses of the JYNNEOS vaccine. However, patients who had previously received the smallpox vaccine continued to experience protective levels of mpox antibodies past 28 days. The researchers hypothesized that smallpox vaccines may increase the adaptability of immune cells. The preliminary results from the new study highlight the need for clinical studies examining the efficacy of an mpox booster dose in order to inform public health guidelines. “The results presented here indicate that long-term protective immunity might need a booster dose for its maintenance,” concluded Klara Sondén, a deputy state epidemiologist at the Public Health Agency of Sweden.