Known vaccine-associated adverse events

Abstract

The most beneficial worldwide health interventions in the twentieth century include vaccines. Despite and in part because of their success, adverse events following immunization (AEFIs) are increasingly scrutinized. Thus, there is a need for practitioners to be aware of common and expected as well as serious or more publicized AEFIs. Likewise, practitioners need to be aware of the challenges involved in differentiating AEFIs truly caused by vaccines (causally related) from events that coincidently occur soon after vaccines (temporally related). Consequently, despite being listed on Internet sites or in databases, e.g., Vaccine Adverse Event Reporting System (VAERS), some AEFIs may be temporally related but not causally related to vaccines, e.g., autism. The first section of the chapter reviews common but transient AEFIs that are expected to have few if any sequelae, e.g., fever, pain at the injection site, local reactions, febrile seizures, syncope after injection. In the second section, more serious and less common reactions are reviewed, e.g., injection sites abscesses, extreme local swelling, neurological AEFIs, anaphylaxis/hypersensitivity. The third section reviews reactions peculiar to selected vaccines, e.g., hypotonic hyporesponsive episodes (HHE) following whole cell or acellular pertussis-containing vaccines. Next is a short section on special vaccines. The chapter concludes with a section on causality and the concept of genetic predisposition to certain diseases that unfold coincidentally in the first years of life when children receive many vaccines. The latter section was added because it is challenging to help families understand that some of the events that present during the first years of life are not causally related to a vaccine simply because they occur soon after them.