Pennsylvania's confirmed measles cases rose sharply from 86 the previous week to 1,222 as of Wednesday, according to the state. Six measles-associated deaths have been confirmed.
The CDC said it would deploy a scientist from its epidemic intelligence service to assist the response. 'CDC will continue working closely with Pennsylvania health officials to provide the expertise and support needed to respond to the outbreak and protect public health,' a CDC spokesperson told NBC News. The spokesperson added that CDC director Dr Erica Schwartz recommends the MMR vaccine 'as the most effective way to prevent measles and protect against infection'. The agency is also releasing nearly $4m to support Pennsylvania's response.
Lancaster county, the focus of the outbreak with more than 415 confirmed cases as of 9 October, is the largest county in the state without its own health department, and local officials say that puts it at a clear disadvantage. The plain community, or Amish, who have historically had lower rates of vaccination, make up about 8% of the county's population.
The Guardian reported earlier this month that Pennsylvania was bracing for a wave of cases, with some public health officials concerned it was 'only a matter of time' before the disease spread beyond the outbreak's centre.