The Effects of Pneumococcal and Haemophilus Vaccines in Children Under 5 Years of Age on Severity of Illness and Deaths From Infections Other Than Those Conditions That the Vaccine is Designed to Prevent, and on All-cause Mortality and All-cause Hospitalisation: A Systematic Review Protocol

Abstract BackgroundVaccination in children has reduced morbidity and mortality worldwide from infectious diseases. It has been suggested that vaccines have beneficial effects beyond the diseases they are designed to prevent. These are known as “non-specific effects” and include reductions in severity of illness and hospitalisation for illnesses other than those the vaccine is designed to prevent. This protocol will focus specifically on the non-specific effects of pneumococcal and haemophilus influenza vaccines in children under 5 years of age.MethodsWe will systematically search Medline, Embase, Cochrane Central Register of Controlled Trials, the European Union Clinical Trials Register and the clinicaltrials.gov databases using a broad range of search terms pertaining to pneumonia, morbidity, mortality and children to identify potentially relevant studies. These will be limited to randomised controlled trials, quasi randomised controlled trials and cohort studies in English. Two independent reviewers will conduct all levels of screening, data abstraction, and quality appraisal (using the Cochrane risk of bias tool). DiscussionOur results can be used by researchers and policy-makers to identify if there are non-specific effects of pneumococcal and haemophilus vaccines which should be explored further. The review will be also be of interest to patients and clinicians to determine if vaccines have beneficial effects beyond the illnesses they are designed to prevent.Systematic review registrationThe systematic review protocol is registered with the PROSPERO database, Registration number: CRD42020146640.