Non-specific effects of childhood vaccines

Abstract

Evidence of any “off target” effects remains weak and vulnerable to biases Non-specific effects of vaccines or “off target effects” as they are sometimes called can be defined as effects of a vaccine beyond their intended target pathogen or disease. These effects can be beneficial as well as harmful.1 2 3 The published evidence on non-specific effects of childhood vaccines remain confusing, so the linked systematic reviews by Higgins and colleagues (doi:10.1136/bmj.i5170)4 and Kandasamy and colleagues (doi:10.1136/bmj.i5225)5 looking at clinical and immunological non-specific effects are welcome. The systematic reviews were commissioned by the WHO Strategic Advisory Group of Experts (SAGE) to decide if there was enough evidence to consider changes in scheduling or co-administration of certain vaccines.6 It is important to emphasise that the systematic reviews were not intended or designed to assess if these vaccines are safe or should continue to be recommended for children. It is beyond debate that BCG, diphtheria, tetanus, pertussis (DPT), and measles containing vaccines (MCV) are safe. These vaccines have …