GENEVA, July 7 (Xinhua) -- World Health Organization (WHO) experts said on Tuesday that research on the airborne transmission of COVID-19 was not yet definitive but the possibility cannot be ruled out.

At a press conference in Geneva, Prof. Benedetta Allegranzi, technical lead for Infection Prevention and Control at the WHO, said that aerosol or airborne transmission, among other fields of research, is "really growing and for which there is some evidence emerging but is not definitive."

"And therefore, the possibility of airborne transmission in public settings especially in very specific conditions -- crowded, closed, poorly ventilated settings -- cannot be ruled out," she emphasized.

"We acknowledge that there is emerging evidence in this field, as in all other fields regarding the COVID-19 virus and pandemic, and therefore, we believe that we have to be open to this evidence and understand its implications regarding the modes of transmission and also regarding the precautions that need to be taken," she explained.

"However, the evidence needs to be gathered and interpreted and we continue to support this," she added.

Dr Maria Van Kerkhove, technical lead for WHO Health Emergencies Programme, said the global health organization has been working on this for several weeks now and engaged with a large number of epidemiologists, clinicians, engineers, mathematical modelers, "to try to consolidate the growing knowledge around transmission."

"We are producing a scientific brief on summarizing where we are ... so we will be issuing our brief in the coming days and that will outline everything that we have in this area," she noted.

A group of 239 scientists have written recently in an open letter, claiming that COVID-19 can be transmitted through air and urging the international community to implement control measures to prevent its airborne transmission.