Infectious disease experts warn of measles surge, including new variants

A disease that public health once considered largely tamed is reasserting itself with unfamiliar force. Measles cases across the United States have climbed to their highest levels in thirty years, with Pennsylvania emerging as a center of concern where physicians are encountering viral forms they do not fully recognize. What troubles experts most is not merely the numbers, but the possibility that the virus is changing in ways that outpace the immunity we believed we had secured — a reminder that the work of protecting collective health is never truly finished.