Epidemiology of H1N1 (2009) Influenza among Healthcare Workers in a Tertiary Care Center in Saudi Arabia: A 6-Month Surveillance Study

BACKGROUND. Certain emerging infections, such as severe acute respiratory syndrome and avian influenza, represent a great risk to healthcare workers (HCWs). There are few data about the epidemiology of H1N1 influenza among HCWs. METHODS. We conducted a prospective surveillance study for all HCWs at King Abdulaziz Medical City (Riyadh, Saudi Arabia) who were confirmed positive for H1N1 influenza by polymerase chain reaction (PCR) from June 1 through November 30, 2009. RESULTS. During 6 months of surveillance, 526 HCWs were confirmed positive for H1N1 influenza. The distribution of these cases showed 2 clear outbreaks: an initial outbreak (peak at early August) and a shorter second wave (peak at end of October). Among all PCR-confirmed cases, the attack rate was significantly higher in clinical HCWs than in nonclinical HCWs (6.0% vs 4.3%; P < .001) and in HCWs in emergency departments than in HCWs in other hospital locations (17.4% vs 5.0%, P < .001). The percentage of HCWs who received regular influenza vaccination was greater for clinical HCWs than for nonclinical HCWs (46.2% vs 24.6%; P < .001). The majority of HCWs with confirmed H1N1 influenza were young (mean age +/- standard deviation, 34.5 +/- 9.5 years), not Saudi (58.4%), female (55.1%), and nurses (36.1%). Approximately 4% of women who were less than 50 years old were pregnant. Reported exposures included contact with a case (41.0%), contact with a sick household member (23.8%), and recent travel history (13.3%). Respiratory symptoms (98.0%), including cough (90.1%), were the most frequently reported symptoms, followed by muscle aches (66.2%), fever (62.5%), headache (57.9%), diarrhea (16.5%), and vomiting (9.8%). None of these HCWs died, and all recovered fully without hospital admission. CONCLUSIONS. The results confirm the vulnerability of HCWs, whether clinical or nonclinical, to emerging H1N1 influenza.