Parotid swelling due to Hoshino strain following MMR vaccination in iranian immunization program

This paper reports two seronegative cases of parotid swelling following MMR vaccination,which contains Hoshino strain of mumps virus.This study showed a high,(5%) potential reactogenicity induced by Hoshino strain of current MMR vaccine administered in Iranian EPI.The rate of complication of parotid swelling following national immunization against mumps is more than natural infection.Based on the results of this report, there is the first report of occurrence of parotid swelling 31 days following MMR vaccination.This reaction or complication may not be dependent on the vaccine dose,because one of cases presented parotid swelling following taking one fifth of conventional dose of vaccine.It must be considered this strain may be with high rate of complication and be the subject of change of mumps strain of this vaccine in national immunization program of Iran.