The ratings aren't intended as a detailed threat assessment and don't indicate which pathogen is most likely to trigger the next pandemic, but instead are a guide for research investment.
Of the 4 infected men aged 27 to 78 years, 1 was exposed to the virus in a hospital, and 1 was indirectly exposed to camels and their raw milk.
The roadmap was created under the guidance of 50 scientific leaders.
The case is the fifth reported in Saudi Arabia this year.
The index case-patient, who died from his infection, shared a hospital room with the second patient identified.
The group steered away from defined cutoff points such as "droplets" and "aerosols" that scientists have used to distinguish larger particles from smaller particles.
Two people had connections to camels, but the exposure source is still unknown for two of the patients.
MERS-CoV antibody reactivity was identified in 7 of 48 camel-slaughterhouse workers (15%).
Groups announced new clinical trials and more support for universal flu, MERS, and mpox vaccines.
Prioritized COVID tracking and effects from COVID control measures likely contributed to a drop in MERS cases, but the threat remains, the WHO said.
