Serological Surveillance Pilot

Population Based System for Serological Surveillance of Influenza

 

Background:
Rapidly undertaken age-stratified serology studies can produce valuable data about a new emerging infection including back-ground population immunity and sero-incidence during an influenza pandemic. This information is key to predicting its future course and implementing optimal intervention strategies. Traditionally sero-epidemiology studies have used surplus laboratory sera with little clinical information or have been expensive detailed population-based studies, which are slow to implement. We propose collecting population-based sera from the Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC), a sentinel network with extensive clinical data.

Aim:
To pilot a method for provision of nationally representative serum samples and associated patient data to measure sero-positivity and sero-incidence due to seasonal influenza and other infections of public health importance. This will fill gaps in pandemic and seasonal flu preparedness, link population-based sero-epidemiology with RCGP RSC seasonal influenza disease surveillance data, and create a population- based serology bank for investigation of other important infections.

Study design:
Participating practices from the sentinel GP network included in the pilot will provide blood from an age and gender stratified sample of consenting patients to be stored and tested by PHE in order to set in context other measures of influenza surveillance in the population and assess population exposure and susceptibility.

Setting and Participants:
We will recruit 5-6 RCGP RSC practices already taking nasopharyngeal virology swabs. Patients who attend for a scheduled blood test will be consented to donate additional blood samples. Approximately 100-150 residual blood samples will be collected from each of the following age-bands – 18-29, 30-39, 40-49, 50-59, 60-69, 70+ years for the period May – August 2018. We will feed back as each age-band completes the required sample number.

Method:
We will send the samples to the Public Health England (PHE) Seroepidemiology Unit (SEU) for processing and storage. These samples will be tested at the PHE Respiratory Virus Unit for influenza antibodies, using haemaglutination inhibition assays (HAI). Serology results and current surveillance data will be pseudonymised, sent to the RCGP RSC and combined using existing processes at the RCGP RSC secure hub. The flu seroprevalence results from the RCGP cohort will be compared against those from the annual PHE flu residual serosurvey.