A new study found five variants of the Middle East respiratory syndrome coronavirus (MERS-CoV) circulating between humans and camels, while a second study revealed promise from an experimental camel vaccine.

Both published Dec. 17 in the journal Science, the camel sampling study was initiated by a Hong Kong team and included researchers from Saudi Arabia, Australia and Egypt, while the vaccine study was initiated at the Netherlands’ Erasmus Medical Center and includes German and Spanish scientists.

Sampling over 1,300 camels in Jeddah, Taif, and Riyadh in 2014 and 2015, the researchers found 25.3 percent positive for coronaviruses, 12 percent of which particularly harboring MERS-CoV.

Local Arabian camels were more likely to contain the virus than imported ones from Sudan and Somalia. Young camels or those younger than a year old, too, tended most to be infected, their rate almost double that of camels in other age ranges.

Analysis of 93 full-gene sequences in camels also revealed five variants of the virus, such as the fifth one – a recombination of the third and fourth – resulting in human MERS-CoV outbreaks in Middle East and South Korea.

In the second research, the team tested a vaccine for camels that uses a weakened poxvirus – called MVA-MERS-S and developed two years ago – delivering the MERS-CoV spike protein.

Only mild symptoms developed in vaccinated camels within three weeks after receiving their shots. The experimental vaccine also appeared to protect against camelpox virus, another condition afflicting the country’s camel population.

Dr. Michael Osterholm, director of University of Minnesota’s Center for Infectious Disease Research and Policy, said the first study provided some evolutionary insight into the virus that health official worldwide need to pay attention to.

Osterholm added that a camel vaccine can potentially help curb MERS-CoV’s spread to humans. "Even if the vaccine is moderately effective, it would still be important," he said.

The researchers are now gearing up to test the candidate virus in humans, as the vaccine is already partly qualified for human clinical trials.

No human vaccine for MERS-CoV currently exists, although some from candidate viruses are underway.

Human MERS-CoV infection, limited to those with close contact to infected patients, first manifested in Saudi Arabia in 2012, since then causing over 1,600 documented cases. Over one-third of reported cases led to death.

Specifically prone to life-threatening symptoms of the infection are people with diabetes, long-term lung condition, kidney failure, and other illnesses.