Abstract
Whether to vaccinate or not is currently a hot topic in social discourse. Despite the majority view that childhood vaccination is safe and effective, websites and social media content opposing such vaccination are common. In this study, we searched the internet platforms Google, Facebook and YouTube for childhood vaccine information. We made every attempt to minimise selection bias generated by internet algorithms. We compared the displayed stances of vaccine information retrieved. Most of the information had a clearly stated stance on vaccines or made some sort of recommendation on whether or not to vaccinate. Despite our careful attempt to search comprehensively and systematically for vaccine information with as little bias as possible, this search yielded a sizeable minority of vaccine negative information. This research shows that negative vaccine information persists and is readily accessible online despite algorithm and policy changes in recent years, even when searching in the least biased way possible. It is important that vaccine-promoting entities and agencies continue to make every effort to maximize their presence online so that parents searching the internet to answer the question 'should I vaccinate my child?' continue to receive vaccine positive information. (C) 2020 Elsevier Ltd. All rights reserved.