美国“消除”麻疹后再现疫情 专家：恐是“疫苗犹豫”惹的祸

Core Viewpoint - The resurgence of measles in the United States, which was declared eliminated in 2000, is attributed to a decline in vaccination rates and the highly contagious nature of the virus [1][2]. Group 1: Measles Resurgence - In 2025, the U.S. reported 1,284 confirmed measles cases, a significant increase from the average of 180 cases per year [1]. - The basic reproduction number (R0) of measles is estimated to be 18, meaning one infected person can infect 18 susceptible individuals [2]. - The likelihood of infection for unvaccinated individuals who come into contact with a measles patient is approximately 90% [2]. Group 2: Vaccine Hesitancy - Vaccine hesitancy has emerged as a major barrier to maintaining herd immunity, particularly in developed countries where anti-vaccine movements have gained traction [3][4]. - The global death toll from measles has decreased by about 79% due to widespread vaccination, affecting approximately 171 million people [3]. - The decline in vaccination rates in developed countries has led to the resurgence of previously controlled infectious diseases [4]. Group 3: Health Risks and Responses - Measles can lead to severe complications such as laryngitis, pneumonia, myocarditis, and encephalitis, with at least three reported deaths in the recent U.S. outbreak [5]. - It is crucial for individuals, especially those in vulnerable groups, to consult healthcare professionals regarding vaccination to prevent severe outcomes [5]. - Continuous monitoring and effective response strategies are essential to maintain low measles incidence rates and manage outbreaks effectively [6].