Vaccine Effectiveness against Influenza in 2015/16 in Hospital and Ambulatory Medical Care Facilities: Polish Results of the European I-MOVE+ Multicenter Study

Abstract

Influenza vaccination is the best measure available to prevent seasonal influenza infection. The majority of studies on vaccine effectiveness in the 2015/16 season conducted in the European I-MOVE+ Project, show that a match between the circulating influenza strains in the general public and those included in the vaccine for the Northern Hemisphere was low to moderate. As part of I-MOVE+, Poland has implemented a case control negative study design and molecular biology methods, such as real time RT-PCR, to assess the vaccine match and effectiveness. The research described herein consisted of two major influenza vaccine effectiveness investigations conducted in Poland in the 2015/16 season. The general practice part of the study included 228 cases consisting of 159 type A, 65 type B, and 4 coinfections (types A + B), and 312 negative control cases. The hospital study part included 26 cases consisting of 21 type A, 2 type B, and 3 coinfections, and 13 negative control cases. The data were collected from patients of all ages recruited by 46 volunteering doctors in 15 Poland's provinces and three hospitals, respectively. In both study parts, only were seven patients and 12 control subjects vaccinated. Low vaccine coverage, a major limitation of the Polish study, makes the calculation of vaccine effectiveness for the Polish population hardly applicable statistically. Despite the crudeness of data, they were included into the common European analysis. The overall vaccine effectiveness amounted to 21.0% (95% CI: 74-122). It was somehow better for type B virus: 53.9% (95% CI: 47-87) and type A virus: 23.6% (95% CI: 83-185). A larger sample size is needed to achieve a desired interpretation of results on influenza vaccine effectiveness in Poland.

Surveillance of medically‐attended influenza in elderly patients from Romania—data from three consecutive influenza seasons (2015/16, 2016/17, and 2017/18)

“…We recorded a total number of seven cases of influenza in patients who had been vaccinated in the respective current season; most of these vaccine failures occurred in the 2015/16 season. The adjusted influenza vaccine effectiveness (IVE) in elderly patients (defined as 60 years and older) for the 2015/16 season in Spain was low (20.2% for preventing hospital admission with A(H1N1)pdm09), 34 similar to the data from the I‐MOVE+ study in Poland, reporting an overall vaccine effectiveness of 21.0% 35 . For Romania, the low vaccine uptake for the previous influenza seasons did not allow an adequate calculation of the IVE, with very small numbers of cases and controls included in the formula, which led to an adjusted IVE against hospitalized A(H1N1)pdm09 infection reported at −22.6%, but with a very wide confidence interval (−490.3% to 74.6%) 36 …”