Kelvin and Zambon examines influenza imprinting in childhood and the influence on vaccine response later in life. First impressions are important and often long-lasting. The first influenza virus infection during childhood, termed immune imprinting, is recognized for its influence on subsequent infections and vaccinations. The imprinting event initiates a cascade of innate and adaptive immune responses leading to an immunological memory retained over a person's lifetime. Recent studies in Eurosurveillance report potential implications for vaccine responses. Skowronski et al. with the Canadian Sentinel Practitioner Surveillance Network and Kissling et al. with the Influenza Monitoring Vaccine Effectiveness (I-MOVE) in Europe observed evidence of an age-related cohort effect reducing vaccine protection during the 2018/19 influenza season, which they infer occurred as a result of an immunological imprinting event.