Emergency Medical Services Utilization during an Outbreak of Severe Acute Respiratory Syndrome (Sars) and the Incidence of Sars-Associated Coronavirus Infection among Emergency Medical Technicians

Objectives: This was a study to evaluate the utilization of emergency medical services (EMS) systems during the outbreak of severe acute respiratory syndrome (SARS), and to assess the incidence of infection among emergency medical technicians (EMTs). Methods: This was a prospective, observational study conducted in the EMS system of Taipei, Taiwan. Probable/suspect cases of SARS were defined by World Health Organization criteria. SARS-related transports were categorized into 1) requests from hospitals for probable/ suspect cases of SARS, 2) quarantined individuals, and 3) febrile persons. City ambulances were organized into teams A , B, and C for transports of different perceived risks. Data on the EMS volume, the transport category, the final SARS status of patients, and the EMT responsible for the transports were collected. The EMS projected volume was computed by previous years' data and compared with that collected. The SARS incidence among EMTs was assessed by investigating probable SARS (P-SARS) and by surveying the seroprevalence of SARS-associated coronavirus (SARS-CoV) antibody. Results : From March 18 to June 19, 2003, there were 7,961 EMS transports, similar to the volume projected from previous years (7,506) (95% CI = 6,688 to 8, 324). Of these, 1,760 (22.1%) were SARS-related. When SARS-related transports were excluded, there was a 12.2% decrease (95% CI = 11.4% to 12 .9%) in EMS activities. Requests from hospitals , quarantined individuals, and febrile citizens accounted for 23%, 18%, and 59% of SARS-related transports. Among the 397 P-SARS cases in the city of 2.65 million people ( incidence 0.01%, 95% CI = 0.01% to 0.02%), 138 (35%) required EMS transports. Two EMTs working in team C, the team with the lowest risk, developed P-SARS. One of them died soon thereafter. The incidence of P- SARS was 0.6% (95% CI = 0.2% to 2.2%), or 0.1% (95% CI = 0.03% to 0.4%) per transport. SARS-CoV serology was available in 74.1% of EMTs who were alive. In addition to the surviving P-SARS EMT, one EMT from team A, the team with the highest risk, was seropositive. Combining P-SARS and the seropositive case, three EMTs were infected (incidence 1.3%, 95% CI = 0.4% to 3 .6%). No patient transported by the infected EMTs developed SARS. The hospitals serving EMS by the infected EMTs had been involved in a clustered outbreak prior to the EMTs' infections. Conclusions: During the outbreak of SARS, the overall EMS volume did not change significantly, but the non -SARS EMS activities decreased. Compared with the general population, EMS providers are at higher risk of contracting the SARS virus regardless of different perceived levels of risk. Standard protections and procedures for infection control should be strictly followed during transport and within the hospital environment. Key words: emergency medical services; severe acute respiratory syndrome; emergency medical technicians; utilization; incidence