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ABSTRACT
Elderly individuals have the highest burden of disease from influenza infection but also the lowest immune response to influenza vaccination. A better understanding of the host response to influenza vaccination in the elderly is therefore urgently needed. We conducted a biphasic prospective, population-based study from Dec. 2014 to May 2015 (pilot study) and Sept. 2015 to May 2016 (main study). Individuals 65–80 y of age were randomly selected from the residents' registration office in Hannover, Germany, for the pilot (n = 34) and main study (n = 200). The pilot study tested recruitment for study arms featuring 2, 4, or 5 visits/blood draws. The 5-visit (day 0, 1/3, 7, 21, 70 with respect to vaccination) study arm was selected for the main study. Both studies featured vaccination with Fluad™ (Novartis, Italy), a detailed medical history, a physical exam, recording of adverse events, completion of a questionnaire on common infections and an end-of-study questionnaire, and blood samples. Response rates in the pilot and main studies were 3.7% and 4.0%, respectively. Willingness to participate did not differ among the study arms (Fisher's exact test, p = 0.44). In both studies, there were no losses to follow-up. Compliance with study visits, blood sampling and completion of the questionnaires was very high (100%, >97%, 100%, respectively), as were participants' acceptance of and satisfaction with both phases of the study. The low response rates indicate the need for optimized recruitment strategies if the study population is to be representative of the general population. Nonetheless, the complex prospective study design proved to be highly feasible.
Abbreviations
| BCR | = | B cell receptors |
| BIMS | = | Biobank Information Management System |
| BMI | = | Body Mass Index |
| CMV | = | cytomegalovirus |
| CRC | = | Clinical Research Center |
| EDTA | = | ethylenediaminetetraacetic acid |
| EMA | = | European Medicines Agency |
| FACS | = | fluorescence-activated cell sorting |
| HAI | = | hemagglutination-inhibition |
| HUB | = | Hannover Unified Biobank |
| MN | = | microneutralization |
| PBMC | = | peripheral blood mononuclear cells |
| RKI | = | Robert Koch Institute |
| RNA | = | ribonucleic acid |
| SOP | = | Standard Operating Procedure |
| SPREC | = | Sample PREanalytical Code |
| TCR | = | T cell receptors |
| WHO | = | World Health Organization |
Disclosure of potential conflicts of interest
The authors declare that they have no competing interests relating to the conduct of this study or the publication of this manuscript.
Acknowledgments
We would like to thank the study teams at the Clinical Research Center Hannover, in particular, Ms. Katrin Paul (study nurse) and at the Hannover Unified Biobank for their contribution to data collection and processing of biosamples. We thank Ms. Sabrina Wieghold (Study Center Hannover of the German National Cohort health study), and Ms. Conni Senske (Helmholtz Centre for Infection Research, Braunschweig, Germany) for supporting the recruitment process, and Nina Burgdorf, Mohamed A. Tantawy and Aaqib Sohail (TWINCORE, Hannover, Germany) for technical support.
Funding
This work was supported by iMed – the Helmholtz Association's Cross-Program Initiative in Personalized Medicine.
Authors' contributions
MKA participated in study planning, was responsible for the recruitment of study participants, performed statistical analysis and wrote the first draft of the manuscript. PR participated in study planning and writing of the manuscript and performed laboratory analyses. MWA, LJ, DW, and AR participated in the recruitment of study participants and collected data and blood samples during the home visits in the pilot study. MM and CS participated in study planning, and collected data and biosamples at the study center. MT collected data and biosamples at the study center. KP participated in recruitment of study participants and data analysis. BP participated in study planning and recruitment of study participants. IB, JP, NK and TI were responsible for biobanking and participated in study planning. JP participated in writing of the manuscript. ST participated in laboratory analyses. AT was responsible for data intergration in tranSMART. CAG is a principal investigator of the project; he planned the study and reviewed the manuscript. FP is a principal investigator of the trial; he planned the study, co-wrote the manuscript and had access to all data and takes full responsibility for their integrity. All authors critically reviewed the manuscript and approved the final version of the manuscript.