(Reuters) – The United States has narrowly retained its measles elimination status by World Health Organization standards, despite seeing more than 1,200 measles cases so far this year in the worst outbreak since 1992, federal health officials said on Friday.

The U.S. Centers for Disease Control have attributed the country’s worst outbreak over the past year, which began in New York on Oct. 1, 2018, in large part to parents who declined to vaccinate their children.

The disease was declared eliminated in the United States in 2000, meaning there was no continuous transmission for a year, and the outbreak in New York this year narrowly avoided meeting that threshold. The last rash onset associated with a measles case in New York was recorded on Aug. 19.

“Both jurisdictions have since passed two incubation periods for measles with no additional reported cases associated with these outbreaks as of October 1, 2019; however, continued vigilance is important to ensure that elimination is sustained,” the CDC said in a report released on Friday.

Federal health officials have attributed this year’s outbreak to U.S. parents who refuse to vaccinate their children. These parents believe, contrary to scientific evidence, that ingredients in the vaccine can cause autism.

(Reporting by Gabriella Borter in New York; Editing by Scott Malone and Bernadette Baum)