A new type of coronavirus believed to have originated in dogs was detected among patients hospitalised with pneumonia in 2017-2018, and may be the eighth unique coronavirus known to cause disease in humans if it is confirmed as a pathogen, a study said.

Researchers in the study, published in the Clinical Infectious Diseases journal on Thursday, said their findings underscored the public health threat of animal coronaviruses.

The researchers said they had tested nasal swab samples taken from 301 pneumonia patients at a hospital in the east Malaysian state of Sarawak. Eight of the samples, mostly from children under 5 years old, came back positive for a canine coronavirus.

Further genomic sequencing found that the new strain, named CCoV-HuPn-2018, shared characteristics of other coronaviruses known to have infected cats and pigs but was mostly similar to one that is known to have infected dogs.

It also contained a genetic deletion, or mutation, that was not found in any known canine coronaviruses but was present in human strains such as SARS-COV and SARS-COV-2, the virus behind the Covid-19 pandemic. The source of the SARS-COV-2 coronavirus itself, whether animal or other, remains unclear.

The paper's authors said the findings indicated that the virus likely recently jumped from animals to humans, but stressed that more studies were needed to determine whether it can be transmitted between people.

They also said it was unclear whether the virus could make people sick, noting that it was possible it was merely "carried" in the patient's airways without causing disease.

There are seven coronaviruses known to cause disease in humans: four that cause the common cold, and three that cause the diseases commonly known as SARS, MERS and Covid-19.