Influenza vaccine effectiveness estimates in Europe in a season with three influenza type/subtypes circulating: the I-MOVE multicentre case-control study, influenza season 2012/13

In the fifth season of Influenza Monitoring Vaccine Effectiveness in Europe (I-MOVE), we undertook a multicentre case-control study (MCCS) in seven European Union (EU) Member States to measure 2012/13 influenza vaccine effectiveness against medically attended influenza-like illness (ILI) laboratory confirmed as influenza. The season was characterised by substantial co-circulation of influenza B, A(H1N1)pdm09 and A(H3N2) viruses. Practitioners systematically selected ILI patients to swab ≤7 days of symptom onset. We compared influenza-positive by type/subtype to influenza-negative patients among those who met the EU ILI case definition. We conducted a complete case analysis using logistic regression with study as fixed effect and calculated adjusted vaccine effectiveness (AVE), controlling for potential confounders (age, sex, symptom onset week and presence of chronic conditions). We calculated AVE by type/subtype. Study sites sent 7,954 ILI/acute respiratory infection records for analysis. After applying exclusion criteria, we included 4,627 ILI patients in the analysis of VE against influenza B (1,937 cases), 3,516 for A(H1N1)pdm09 (1,068 cases) and 3,340 for influenza A(H3N2) (730 cases). AVE was 49.3% (95% confidence interval (CI): 32.4 to 62.0) against influenza B, 50.4% (95% CI: 28.4 to 65.6) against A(H1N1)pdm09 and 42.2% (95% CI: 14.9 to 60.7) against A(H3N2). Our results suggest an overall low to moderate AVE against influenza B, A(H1N1)pdm09 and A(H3N2), between 42 and 50%. In this season with many co-circulating viruses, the high sample size enabled stratified AVE by type/subtype. The low estimates indicate seasonal influenza vaccines should be improved to achieve acceptable protection levels.

Low and decreasing vaccine effectiveness against influenza A(H3) in 2011/12 among vaccination target groups in Europe: results from the I-MOVE multicentre case-control study

Within the Influenza Monitoring Vaccine Effectiveness in Europe (I-MOVE) project we conducted a multicentre case–control study in eight European Union (EU) Member States to estimate the 2011/12 influenza vaccine effectiveness against medically attended influenza-like illness (ILI) laboratory-confirmed as influenza A(H3) among the vaccination target groups. Practitioners systematically selected ILI / acute respiratory infection patients to swab within seven days of symptom onset. We restricted the study population to those meeting the EU ILI case definition and compared influenza A(H3) positive to influenza laboratory-negative patients. We used logistic regression with study site as fixed effect and calculated adjusted influenza vaccine effectiveness (IVE), controlling for potential confounders (age group, sex, month of symptom onset, chronic diseases and related hospitalisations, number of practitioner visits in the previous year). Adjusted IVE was 25% (95% confidence intervals (CI): -6 to 47) among all ages (n=1,014), 63% (95% CI: 26 to 82) in adults aged between 15 and 59 years and 15% (95% CI: -33 to 46) among those aged 60 years and above. Adjusted IVE was 38% (95%CI: -8 to 65) in the early influenza season (up to week 6 of 2012) and -1% (95% CI: -60 to 37) in the late phase. The results suggested a low adjusted IVE in 2011/12. The lower IVE in the late season could be due to virus changes through the season or waning immunity. Virological surveillance should be enhanced to quantify change over time and understand its relation with duration of immunological protection. Seasonal influenza vaccines should be improved to achieve acceptable levels of protection.

[Mumps in Poland in 2010]

INTRODUCTION

Despite of the decline in the incidence rate of mumps which is the main result of the modifications of the Polish Immunization Programme (the vaccination against mumps has become obligatory since 2003), it is still a disease which occurs frequently in children.

OBJECTIVES

The main objective of the present article was to analyze the epidemiological situation of mumps in Poland in 2010 in comparison with the data from previous year. This paper was based on aggregated data published in "Infectious diseases and poisonings in Poland in 2010", "Vaccinations in Poland in 2010", "Case definitions for the infectious diseases used for the surveillance purposes in 2009-2011" and Polish Immunization Programme for 2010.

RESULTS

In Poland in 2010, 2 754 cases of mumps were reported. The incidence rate was 7.2 per 100 000 and was lower in comparison with the incidence rate observed in 2009 (7.7) and five times lower than the median incidence reported in 2004-2008. The highest incidence rate was observed in the children aged 5-9 years (53.9). Thirty two out of2 574 notified cases were hospitalized (1.16%).

CONCLUSIONS

Realization of the vaccination against mumps using conjugate MMR (measles-mumps-rubella) vaccine contributed to the decrease in the incidence rate of mumps in Polish population. The high vaccination coverage implies that the incidence rate of mumps will be still decreasing.

[Chickenpox in Poland in 2010]

INTRODUCTION

Chickenpox is a common childhood disease. It occurs sporadically in persons over the age of 15. Regardless of the fact that chickenpox is considered to be a disease of benign course, it may cause complications of different severity levels and with necessity of hospitalization. Since 2004, a high incidence of chickenpox is observed in Poland.

OBJECTIVES

The aim of the present article was to analyze the epidemiological situation of chickenpox in Poland in 2010 with its comparison to the situation observed in the previous years.

MATERIAL AND METHODS

The epidemiological situation ofchickenpox in Poland in 2010 was analyzed on the basis of aggregated data on infectious diseases published in the annual bulletins, i.e.: "Infectious diseases and poisonings in Poland in 2010" (Czarkowski MP. et al., Warsaw, NIPH-NIH, Chief Sanitary Inspectorate) and "Vaccinations in Poland in 2010" (Czarkowski MP. et al., Warsaw, NIPH-NIH, Chief Sanitary Inspectorate). In the present article the authors also referred to the Polish Immunization Programme for 2010 (annex to the statement of the Chief Sanitary Inspector of 22 October 2009). The data on the number of hospitalized persons and complications due to the chickenpox was derived from the Department - Centre for Monitoring and Analyses of Population Health Status and Health Care System (NIPH-NIH).

RESULTS

In 2010, 183 446 cases of chickenpox were reported. The highest number of chickenpox cases was registered in mazowieckie voivodeship, the lowest--in podlaskie voivodeship. The incidence was estimated at 480.04 per 100 000 population and was significantly higher than the incidence observed in 2009 (367.2). The highest chickenpox incidence, which amounted to 4298.4 per 100 000, was reported in children aged 5-9 years. The highest number ofchickenpox cases (the peak) was reported in the period from January to June. The lowest number of cases was registered in September. The chickenpox incidence was higher in men than women and in the inhabitans of villages (498.6 per 100 000) than in persons residing in towns (468.8). The highest incidence was observed in towns with the number of inhabitants ranging from 55 to 99 thousands (532.2 per 100 000), while the lowest incidence was reported in towns over 100 thousand inhabitants (439.1 per 100 000). Overall, 1007 persons were hospitalized due to the chickenpox. A total of 31 540 persons were vaccinated, of whom 30 513 persons belonged to the age group 0-19 years.

CONCLUSIONS

Since 2004, an increase in the number of reported chickenpox cases is observed in Poland. It is a consequence of improvement in chickenpox registration.