New Delhi, May 26 (IANS): Even as Covid-19 is seeing a decline, the World Health Organisation (WHO) has warned of the threat of an "inevitable" next pandemic of "Disease X", raising concerns across the globe.

Disease X was first coined in 2018 by the WHO, a year before the Covid-19 pandemic struck the world. It is among the WHO's "Blue print list priority diseases" that could cause the next deadly pandemic and includes Ebola, SARS, and Zika.

"Disease X represents the knowledge that a serious international epidemic could be caused by a pathogen currently unknown to cause human disease," the WHO said. The Blueprint list highlights infectious diseases for which we lack medical countermeasures.

According to the Coalition for Epidemic Preparedness Innovations (CEPI), "the threat of Disease X infecting the human population, and spreading quickly around the world, is greater than ever before".

Some public health experts believe the next Disease X will be zoonotic, meaning it will originate in wild or domestic animals, then spill over to infect humans, as Ebola, HIV/AIDS, and Covid-19.

More than 1.6 million viruses are yet-to-be-discovered, and viral species from these viral families are estimated to exist in mammal and bird hosts -- the most important reservoirs for viral zoonoses.

"This isn't the stuff of science fiction. This is a scenario we have to prepare for. This is Disease X," Dr. Richard Hatchett, of the CEPI, was quoted as saying to the Telegraph.

Hatchett said that the world may not be able to "prevent new pathogens from emerging", but "focus, commitment, and investment" can help prevent the devastation they cause.

At the recently held 76th World Health Assembly meet, WHO chief, Tedros Adhanom Ghebreyesus, also issued a stark warning, urging the world to prepare for the next pandemic, which he believes could be even deadlier than Covid-19.

"We must strengthen systems and tools for epidemic and pandemic preparedness and response at all levels," he said, highlighting that the end of Covid-19 as a global health emergency does not signify the end of its threat.

In addition, he emphasised the risk of another pathogen emerging with greater chances of devastation.

"The threat of another variant emerging that causes new surges of disease and death remains, and the threat of another pathogen emerging with even deadlier potential remains," he reportedly said.

"It is not an exaggeration to say that there is potential of a Disease X event just around the corner," Pranab Chatterjee, researcher at the Department of International Health at Johns Hopkins Bloomberg School of Public Health in Baltimore, was quoted as saying to the National Post.

Chatterjee said surveillance may be "a key approach in our ability to detect a spillover event before it becomes too widespread".