Pennsylvania is experiencing its largest measles outbreak this century, with over 1,300 cases reported in 2026 compared to just 16 cases in 2025. The surge has prompted state health officials to announce the first two measles-related deaths in 35 years, both affecting infants. In response, thousands of Pennsylvania parents are vaccinating their babies as early as six months old with the MMR vaccine, which is typically given between 12 and 15 months. Lancaster County has become the epicenter of the outbreak, accounting for more than a third of Pennsylvania’s cases.
Early vaccination presents a medical trade-off. The MMR vaccine cannot be administered before six months because maternal antibodies interfere with immune response, making the vaccine only 58% effective when given before nine months compared to 83% effectiveness at nine months or older. However, research presented at a medical conference suggests most U.S. babies lack protective measles antibodies by six months, indicating infants may be vulnerable to the disease earlier than previously believed. Medical experts agree that early vaccination is warranted during active outbreaks, as measles poses serious risks to infants, including death and permanent complications such as deafness and blindness.
Source: Read the full story at CIDRAP
This summary was written with AI assistance from the linked source.
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