Vaccine Safety

By: Dr. May Montellano, MD

Date: April 30, 2020

Vaccine development, in general, is peculiar when compared to other pharmaceutical products. Unlike other therapeutic or non-therapeutic drugs, vaccines are given in majority to healthy people. This very important fact poses a greater risk and, therefore, it is a must that the vaccine should show a very good safety profile prior to use in the general population.

As with any other pharmaceutical product, vaccines also undergo several phases of development. It starts from the discovery of an antigen to preclinical testing, until it is brought for human use in the clinical phases. The major difference lies in the fact that in order to show its safety profile, it requires larger number of participants to elicit even the remotest possible adverse events in the clinical trials. From the Phase 1 of clinical development until phase 3 prior to its application for regulatory approval, safety is always part of the main objective. Even after its licensure, safety of vaccines are monitored through the post-marketing surveillance. Monitoring of a vaccine after it is licensed is essential in order to ensure that its benefits continuously outweighs the associated risks.

Stakeholders that are mainly involved in vaccine safety includes the National Regulatory Authorities, WHO thru Global Advisory Committee on Vaccine Safety, National Immunizations commitees, and CDC, among others. 1, 2, 3 As per US FDA 21 CFR 600.3, safety is defined as “relative freedom from harmful effect to persons affected directly or indirectly by a product when prudently administered, taking into consideration the character of the product in relation to the condition of the recipient at the time.” 4 Since safety is relative, risk tolerance may be influenced by factors such as the risk of vaccine-preventable disease vs risk of adverse event associated with the vaccine, the alternative treatments available, and the intended population. Any adverse event reported are carefully assesed before it is reported as a vaccine product or immunization-related.

A vaccine adverse event is any health problem that happens after vaccination. As such, it might might be truly caused by a vaccine, or it might just be pure coincidence. Some common concerns related to vaccine safety includes the adjuvants or vaccine additives, autism, syncope, febrile seizures after vaccination, thimerosal use, multiple shots, Guillain-Barre syndrome (GBS) and Sudden infant Death Syndrome (SIDS). 2, 5 All these common concerns and risks are carefully researched and studied with still pointing to vaccination as more beneficial that not having at all. Vaccination providers minimize these risks by carefully screening every immunization encounters.




4. US Code of Federal Regulations Title 21