Infections with A(H1N1)2009 influenza virus in Poland during the last pandemic: experience of the National Influenza Center.

This study presents epidemiological and clinical data on non-sentinel patients considered by physicians as suspected to be infected with pandemic A(H1N1)2009 virus, from whom clinical specimens were sent for testing to the National Influenza Center, NIPH-NIH in Warsaw, Poland. Between April 28, 2009 and August 10, 2010, 988 (15.7%) out of the 6,311 specimens were tested by the National Influenza Center, including 798 from non-sentinel sources and 190 from sentinel influenza surveillance network. The non-sentinel specimens were tested by conventional RT-PCR to detect influenza A and in the case of positive specimens - one-step real-time RT-PCR to detect the pandemic virus A(H1N1)2009. In 145 (18.2%) cases, infections with the pandemic virus were confirmed, with the highest number in patients aged 15-25. In 45% of the confirmed cases, a history of travel to other countries was registered. The most common symptoms were fever ≥38°C (72.7%), cough (50%), sore throat, and myalgia (26.1%). In 40.7% of the swabbed patients, clinical and epidemiological criteria for the novel influenza A(H1N1)2009, set by the European Commission, were met. There were, however, specimens from persons without any reasonable indication for testing for the pandemic virus, specimens collected incorrectly, and documentation without basic information. These weaknesses resulted in unnecessary costs and overload of health care units. An improvement should be achieved in the area of communication between different pandemic players in the future. More attention is also needed to ensure that requirements and recommendations are known and used.

Co-infections with influenza and other respiratory viruses.

Clinicians often do not consider the presence of more than one viral etiologic agent in respiratory infection, and in many cases they order diagnostics for influenza viruses or recently even only for A(H1N1)2009 virus. However, in a substantial number of patients with a respiratory tract disease, co-infection with various viral pathogens has been confirmed. Although the association between the occurrence of co-infection and substantially higher severity of disease is still unclear, a rapid and proper diagnostics of wide spectrum of viral respiratory pathogens reveals an accurate picture of the disease and is essential for appropriate therapeutic management and control of infection. In the present study we reported five cases of multiple respiratory infection in hospitalized immunosuppressed patients: two double infections with influenza virus (IV) type A/respiratory syncytial virus (RSV) type A and IV type A/coronavirus (CoV) OC43, one infection with four viruses - IV type A/RSV type A and B/CoV OC43, and two cases of mixed infections caused by five viral agents - IV type A and B/RSV type A and B/ parainfluenza type 3 or CoV OC43. Each patient had an underlying chronic disease and received immunosuppressive treatment. Despite a low number of tested specimens, our study shows that the inclusions of multiplex PCR methods for diagnostics of respiratory tract infections and the extension of diagnostic strategies by clinicians to detect viruses other than influenza are very important and make a contribution to identifying the true rate of co-infections and their correlation with the clinical symptoms and severity of disease.

The introduction of the SENTINEL influenza surveillance system in Poland--experiences and lessons learned from the first three epidemic seasons.

Influenza surveillance provides information on virus activity and is necessary for the selection of vaccine strains and early warning. To improve this surveillance in Poland, a sentinel surveillance system was introduced in 2004-5 influenza season (SENTINEL). This paper presents results from SENTINEL during three seasons of its existence. Voivodship Sanitary-Epidemiological Stations (VSESs), physicians and the National Influenza Center (NIC) participate in SENTINEL. Laboratory course was performed by the NIC for VSESs. Stations were provided with procedures, report forms, etc. Physicians register number of influenza-like illnesses (ILI) and collect swabs. VSESs perform diagnostic tests. On the basis of information from VSESs, the NIC prepares weekly reports for the entire country. In 2004-5 epidemiological reports were received from 50% of VSESs, while in 2005-6 and 2006-7 from all VSESs. Virological reports were obtained from 37.5% of VSESs (2004-5), 75% (2005-6) and 94% (2006-7). Weekly number of reporting physicians ranged in three consecutive seasons from 165 to 219, 98 to 949 and 696 to 1,054. A total of 399 specimens were tested during the 2004-5 winter; 63 (16%) were positive for influenza and 21 (5%) for other respiratory viruses. In 2005-6, 949 specimens were tested. Influenza infections were confirmed in 47 cases (5%) and infections with other respiratory viruses in 36 cases (4%). A total of 1,195 specimens were tested during the 2006-7 winter; 37 (3%) were positive for influenza and 26 (2%) for other respiratory viruses. SENTINEL provided improvement of influenza surveillance when compared with seasons before 2004. Nevertheless, due to decreasing rate of positive specimens, virological surveillance is the most important part to improve in the next years.

Antibody response to influenza vaccination in patients suffering from asthma.

The aim of the study was to assess humoral response to influenza vaccination in 20 children with bronchial asthma vaccinated with split inactivated vaccine. Response to influenza hemagglutinin was assessed before vaccination and after 1 month by hemagglutination inhibition test. Antibody titers were significantly higher after vaccination than before vaccination. The mean fold increase of antibody levels ranged after vaccination from 12.2 to 53.7. The post-vaccination percentage of patients with protective antihemagglutinin antibody titers>or=40 ranged from 95% to 100%. The percentage of patients with at least a 4-fold increase of anthemagglutinin antibody titers ranged after vaccination from 90% to 100%. The results confirmed the immunogenicity and safety of inactivated influenza vaccine in children with asthma. The registered values of all parameters of the immunological response (mean fold increase, protection rate, response rate) fulfilled the requirements of the Committee for Proprietary Medicinal Products established for healthy people vaccinated against influenza.

Antibody response to inactivated subunit influenza vaccine in patients with Wegener's granulomatosis.

In the present study we investigated the humoral response to inactivated subunit influenza vaccine in patients with Wegener's granulomatosis, who were in clinical and serological remission after immunosuppressive treatment (Group I). The results were compared with patients with Wegener's granulomatosis who were treated immunosuppressively, but were not vaccinated (Group II) and with healthy persons who received the vaccine (Group III). After vaccination, antihemagglutinin and antineuraminidase antibody titers significantly increased in Groups I and Group III subjects when compared with the pre-vaccination values. Post-vaccination protection rates ranged from 51.4% to 74.3% in Group I patients and from 65.7% to 94.3% in Group III subjects. In Group II, the protection rates were between 0% and 21.4%. The response rates ranged from 60% to 74.3% in Group I patients and from 71.4% to 88.6% in Group III subjects. In Group II, the response rates were between 7.1% and 21.4%. The study confirmed the immunogenicity of influenza vaccine in patients with Wegener's granulomatosis and showed similar response in the patients to those present in healthy people.