Pennsylvania has recorded more measles cases, state officials said on Tuesday.
The number of cases in the outbreak rose to 792, including 25 new cases since Sept. 18, the Pennsylvania Department of Health said.
Four of the cases have been among people who received a measles vaccine, authorities said.
The cases have been recorded across 39 counties and resulted in 155 hospitalizations.
Four cases led to death, with state officials marking them as “measles-associated deaths.” Coroners in the counties in which people died have said that two of the deaths were caused by measles, one appeared to have been, and one was not.
Pennsylvania officials are encouraging people to get a measles vaccine, noting they are estimated to provide 97 percent protection against measles after two doses.
The Centers for Disease Control and Prevention advises children to receive one vaccine dose around one year of age, and a second several years later. The CDC recommends that adults who have not previously received a measles vaccine, or survived measles, receive one of the shots.
Nationwide, there have been 3,471 confirmed cases of measles, the CDC said in its latest update on Friday. Ninety-five percent of the cases have been connected to ongoing outbreaks, including the outbreak in Pennsylvania.
Nine percent of the confirmed patients have been hospitalized, according to the CDC.
The public health agency has declined to count the deaths reported by Pennsylvania officials, saying it has not received any death records that “indicate measles is the underlying cause.” The CDC is working with epidemiologists to establish a case definition for measles deaths. No other measles deaths have been reported in the United States this year.
Pennsylvania is using a case definition that includes counting deaths of people who die “from a clinically compatible illness with measles” if the death happens within 30 days of clinically relevant symptoms and it is determined that the death was not due to unrelated causes, such as a car crash.
Dr. Debra Bogen, the Pennsylvania health secretary, recently asked CDC Director Dr. Erica Schwartz for CDC epidemiologists to help combat the outbreak in the state. Bogen said that receiving CDC assistance would be valuable, but said that the CDC’s posture on the deaths reported in Pennsylvania was not acceptable.
“The measles-associated deaths reported by the Department resulted from sound epidemiological investigations, consistent with our published guidance,” Bogen wrote in a Sept. 16 letter to Schwartz.
“The CDC’s choice not to publicly recognize the deaths undermines our response. For this reason, if CDC is unable to transparently and accurately communicate information about those measles-associated deaths, the Department will respectfully rescind our request for [assistance].”