While cases of mumps in the US have remained relatively low in recent decades as compared to the mid-20th Century, outbreaks are possible and concerns over falling vaccination rates have caught the attention of public health officials (CDC, Johns Hopkins). The question will be suspended on 31 December 2026 if still open and the outcome determined using data as provided by the US Centers for Disease Control and Prevention (CDC) when first available for all of 2026 (CDC). Annual cases of mumps in the US last surpassed 500 in 2020 at 694, which was down from 3,780 in 2019. If cases exceed 500, data from the National Notifiable Diseases Surveillance System (NNDSS) will be used to ascertain when the threshold was reached through and including Week 52 (CDC - Stacks, MMWR Week Overview).

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