Update on the Epidemiology of Middle East Respiratory Syndrome Coronavirus — Worldwide, 2017–2023

Middle East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic virus transmitted sporadically from camels to humans. Most reported human Middle East respiratory syndrome (MERS) cases have occurred in or near the Arabian Peninsula. Limited human-to-human transmission can occur after close contact and has resulted in health care-associated outbreaks. Global reported MERS cases, U.S. testing data, and data on incoming U.S. travelers originating in and near the Arabian Peninsula during 2017-2023 were analyzed to guide U.S. MERS preparedness. Global MERS cases reported to the World Health Organization declined during the COVID-19 pandemic and remain substantially lower than during years preceding the pandemic. U.S. MERS-CoV testing numbers also declined and remain low relative to the prepandemic period. Although the number of travelers coming to the United States from in or near the Arabian Peninsula declined during the pandemic, incoming traveler volume returned to prepandemic levels. Further investigations are needed to determine whether the decline in global MERS cases reflects a true decrease in the number of infections, underascertainment of cases, or a combination. U.S. MERS persons under investigation criteria, standard clinical and epidemiologic characteristics used to guide who in the U.S. is tested for MERS-CoV, were updated in 2024 and can be used to guide clinicians and jurisdictional public health partners when considering MERS-CoV testing. Continued and targeted MERS-CoV material surveillance is important to maintaining preparedness and promptly responding to potential MERS cases.