Preschool-located influenza vaccination and influenza-like illness surveillance: an Italian pilot experience

Abstract

Improving influenza vaccination coverage in young children is crucial in reducing the spreading of influenza viruses, thus indirectly protecting the general population. Mass campaign needs to engage all the communities within the target population, overcoming socio-economic and cultural barriers. School-located interventions in some countries were successful in increasing vaccine acceptability and overall immunisation rates. Influenza-like illnesses (ILI) share several symptoms with the ongoing COVID-19 pandemic, posing an important challenge for both diagnostics and public health burden. Self-sampling using non-invasive saliva collection could represent a suitable tool for respiratory infection surveillance. This pilot study was carried out in a very densely populated Italian area, Milan, characterised by a high percentage of non-Italian citizens, often hard-to-reach by preventive programmes. We started a vaccine campaign with live-attenuated influenza vaccine (LAIV), recently recommended in Italy for children aged 2-6, coupled with a saliva-based ILI surveillance system in preschools. We enrolled 432 children from 5 schools in the Milan suburbs, 31.2% of which received the LAIV. Thanks to the undertaken multicultural approach, 59% of the vaccinated children were non-Italian citizens. Despite the COVID-19 preventive measures, i.e., school closure upon positive cases, highly affected the programmed surveillance, all the saliva samples from ILI cases, self-collected by parents at home, resulted adequate for viral molecular testing. With correction measures, this pilot experience could be broadened to a large population, simultaneously allowing for a widespread ILI surveillance and flu immunisation.