He also serves as the Chairman of the Jordanian Paediatric Board Committee and is a part-time consultant at the King Hussein Cancer Center in Amman, Jordan. Among his professional associations, Dr. Hayajneh is a member of the Jordanian Vaccines and Sera Licensing and Re-licensing Committee, the National Immunization Technical Advisory Committee in Jordan, the Jordanian National Infection Control Committee and the Jordan Experts Committee for Pandemics and Swine Flu. Dr. Hayajneh is American Board-certified in both pediatrics and pediatric infectious diseases. Dr. Hayajneh has also been published extensively in peer-reviewed journals, including recent papers in BMC Research Notes, the Journal of Medical Virology, Journal of Pediatric Gastroenterology and Nutrition and Vaccine.