Latest study lifts the fog of vaccine safety
Most of the vaccines routinely recommended in the US are safe with no evidence supporting a causal relationship between the vaccines and adverse events following immunization (AEFIs). Also, most of the AEFIs studied occurred rarely, according to a systematic review presented at the Pediatric Academic Societies (PAS) 2019 Meeting in Baltimore, Maryland, US.
“Healthcare providers desire objective and clear information on a broad range of vaccine safety issues to assist them in answering patient questions,” said Dr Matthew Dudley of Johns Hopkins Bloomberg School of Public Health in Baltimore, who presented the findings at PAS.
Noting that no recent comprehensive reviews on vaccine safety are available to inform providers or the public, Dudley said, “This systematic review provides an update to the scientific evidence assessing possible causal associations of AEFI compiled in the 2012 report from the Institute of Medicine (IOM) and the 2014 report from the Agency for Healthcare Research and Quality (AHRQ), along with clear causality conclusions intended for healthcare providers.”
For 12 out of the 47 AEFIs studied, the review showed that these events were causally related to at least one vaccine (for varicella) currently recommended to the general public in the US. The 12 confirmed adverse reactions included anaphylaxis, febrile seizures, encephalitis, Guillain-Barré Syndrome, arthralgia/arthritis, immune thrombocytopenic purpura, herpes zoster, meningitis, syncope, deltoid bursitis, hepatitis, and disseminated varicella infection. [PAS 2019, abstract 3335.1]
However, most of the reactions are rare, Dudley stressed. In addition, some AEFIs occurred because of improper administration or usage of the vaccine, such as hepatitis and varicella infection reported in individuals with immune deficiency for whom varicella vaccine is contraindicated. Also, adverse events such as arthralgia or arthritis were mild and transient, reported Dudley.
For the remaining 35 AEFIs studied, there was no evidence supporting a causal relationship between vaccines and the AEFIs. In particular, Dudley highlighted that childhood vaccines do not cause autism, in contrary to popular belief.
To further dispel some of the myths surrounding vaccine safety, he also pointed out that there were no causal relationships between vaccines and diabetes, influenza vaccines and asthma or multiple sclerosis in adults, and hepatitis B or DTP* vaccines and Sudden Infant Death Syndrome.
“Although vaccines currently recommended for the general population in the US do cause some adverse reactions, vaccines have an excellent safety profile overall and provide protection against infectious diseases to individuals and the general population,” Dudley concluded.