A comparative study of both epidemic waves of influenza during 2009-January 2010 (H3N2 vs. H1N1v) from the point of view of the outhospital emergency medicine model of SOS Doctors in Athens, Greece

Study of both epidemic waves of influenza

Theodore Spiropoulos, MD, Spyridon Barbas, MD, Manolis Voutsadakis.MD, Ioannis Garofalakis, MD, Lampros Nikolidakis, MD, George Theocharis, MD

During the year 2009 - January 2010 two epidemic waves of influenza occurred in Greece. The first epidemic (S1) happened from January to June 2009 and the prevalent virus strain was of the H3N2 type. The second epidemic wave (S2) occurred from July to January 2010 and the prevalent virus stain was of the H1N1v type.

SOS Doctors is a network of specialized physicians who provide medical home visits in the metropolitan area of Athens, Greece. In this study we analyze our data regarding the two influenza outbreaks of 2009-January 2010.

Aim & Object:

To compare the main clinical characteristics of H3N2 and H1N1v influenza outbreaks. The aim of the study was to contemplate the characteristics of patients suffering from viral respiratory infection, of patients who had performed a rapid test for influenza, of patients suffering from influenza and of patients who were admitted to the hospital after a home visit.

Materials & Methods:

We performed a retrospective observational study regarding patients that had been diagnosed with acute respiratory infection (ARI) from 1/1/2009 to 31/01/2010. We analyzed our database and compared patient characteristics, outcomes and hospitalization rates for both epidemic waves of influenza in 2009-January 2010.


SOS Doctors performed a total of 40377 home visits during 2009 and 5814 (14,4%) patients were diagnosed with viral respiratory infection (2698 in S1 & 3116 in S2). From the above mentioned 5814 patients, 1279 (22%) were tested for influenza with a rapid POC test (202 in S1 & 1077 in S2) and 380/1279 (29,7%) were found to be positive for influenza (96 in S1 & 284 in S2). The rate of positive tests was higher in S1 (p<0,001).
Significantly more women than men were diagnosed with influenza in S1 (p<0.001).
The number of young adults was higher in S2 (p<0.001).
From the 5814 patients with viral respiratory infection only 59 (1,01%) were admitted to the hospital, while 13 out of 380 (3,4%) suffering from influenza (X2 = 14.96, p<0,001). 216 out of 380 (56,8%) patients with a diagnosis of influenza performed by a rapid were prescribed of oseltamivir (74/96 in S1 & 142/284 in S2, X2=5,5 0.025<p<0.01).


Our data suggest that there were no major differences between the two epidemic waves of influenza (H3N2 vs. H1N1v) that occurred in 2009-January 2010 with respect to patient’s outcome, hospitalization rate and need of home visits from the point of view of an outhospital emergency medicine model.