Monitoring of influenza-like symptoms among elderly, an observational study

Influenza, influenza-like illness (ILI) and lower respiratory tract infections
(LRTI) are common and represent a major healthcare problem worldwide. Influenza
facilitates secondary bacterial infection, of the respiratory tract, frequently
by Streptococcus pneumoniae resulting in high hospitalisation and mortality
rates, especially in elderly patients.
Since the winter season of 2003/2004 incidence and prevalence of ILI have been
successfully measured in the Netherlands using an internet-based surveillance
system, highly sensitive to short-term changes and producing incidence figures
comparable to regular influenza surveillance by a sentinel network of GPs,
however, elderly are clearly underrepresented in the internet-based system.
The CAPITA-trial is a placebo-controlled double-blind randomized trial to
determine the efficacy of a new 13-valent pneumococcal conjugate vaccine
(13vPnC) in preventing hospitalization due to pneumococcal CAP. As of now, no
information on respiratory infections is collected outside the hospital
setting.
In this observational study nested within the CAPiTA trial we aim to quantify
the incidence and burden of self-reported ILI and LRTI in the elderly CAPiTA
population, and in addition establish the effect of pneumococcal vaccination
hereon, by using a weekly internet-based questionnaire. Our methodology is
comparable to the previously used web-based influenza surveillance.

Primary Objective:
• To determine the incidence rate of self-reported ILI.
Secondary Objectives:
• To determine the efficacy of 13vPnC in preventing a first episode of
self-reported LRTI.
• To explore the effect of 13vPnC on the incidence of self-reported ILI.
• To determine the incidence of self-reported LRTI symptoms among CAPiTA
participants.
• To determine the proportions of self-reported LRTI episodes for which GPs are
consulted.
• To determine self-reported ILI and self-reported LRTI incidence rates in
different age- and comorbidity-groups.

This is an observational study nested within a placebo-controlled double-blind
randomized trial (CAPITA-trial).

During this study no intervention will take place. Participants of this study
also participate in the CAPiTA trial, a double-blind vaccination trial during
which they received either a 13-valent pneumococcal conjugate vaccine or
placebo.

Subjects will be asked to report whether they have experienced ILI- and/or
LRTI-symptoms on a weekly basis from October 2010 till April 2011, through a
web-based questionnaire. No investigational medicinal product will be
administered during the present study, and the execution of the CAPiTA trial
will not be influenced.