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Vaccine Pharmacovigilance

Immunization safety and vaccine pharmacovigilance efforts must continue to ensure that the vaccine is safe to administer and that the processes provide results to a high degree of credibility and reliability.

In the recent years, for the global population residing either in rural world or urban localities, the words vaccines and its related side effects/adverse drug reactions (ADRs) are not new. A constant humming of COVID-19, various vaccines of COVID-19 and ADRs is there in today’s world. However, vaccines and management of vaccine related side effects is not new to health authorities, medical fraternity and pharmaceutical companies. COVID-19 outbreak severely affected the entire world and the scientists who developed COVID-19 vaccines; global vaccination drives and their side effects brought the field of vaccine pharmacovigilance in limelight.

World Health Organization defines Vaccine Pharmacovigilance (PV) as "the science and activities relating to the detection, assessment, understanding and communication of adverse events following immunization and other vaccine or immunization related issues and to the prevention of untoward effects of the vaccine or immunization".

The appropriate terminology for vaccine related ADR is Adverse Event Following Immunization (AEFI). It means any untoward medical occurrence which follows immunization and which does not necessarily have a causal relationship with the usage of the vaccine.

Vaccine safety ensures and monitors the safety of all aspects of immunization, like vaccine quality, AEFI, vaccine storage and handling and administration of vaccines.

Though there is a difference between vaccines and drugs, nowadays health authorities and some of the pharmaceutical companies are developing an integrated vigilance system to deal with all the adverse events whether from drugs or vaccines. Technological intervention at various checkpoints of PV process can help in standardized AEFI reporting for assessment and deployment of safety measures for betterment of mankind.

The sudden emergence of COVID-19 brought the world to a standstill and revealed how massively underprepared the global community was to deal with a problem of this scale. To curtail the spread of the virus, vaccination efforts were fast tracked and the usual protocols had to be flexibly managed to ensure that the world could return back to normalcy. Given that administration of the vaccines has been a global effort, monitoring AEFI has gained a new importance.

Rushing through the developmental phase that lasts for several years and one that almost all vaccines go through has done little to inspire confidence among the global population. To strengthen the public’s belief in the vaccine PV process, a fine balance needs to be struck between AEFI reporting and reminding people of the dangers of COVID-19. AEFI reporting faces certain challenges in mass vaccination efforts, such as the one being carried out now and these merit further investigation.

AEFI reporting challenges

Routine immunization is vastly different from mass vaccination due to the sheer volume and pace of inoculation. This increases the likelihood of immunization errors leading to more AEFIs.

It is also difficult to pinpoint which adverse events are directly related to the vaccine and which are not. Furthermore, clinical trials may not even detect rare side effects. Anecdotally, this was observed with AstraZeneca’s COVID-19 vaccine when reports of blood clots caused by the vaccine led to its distribution being halted. Upon investigation, the European Medicines Agency (EMA) concluded no conclusive evidence of a linkage between blood clots and the AstraZeneca vaccine. 

This example highlights the need for better reporting standards in vaccine pharmacovigilance. But following these AEFI standards isn’t always easy due to several factors listed below

Variable and asymmetrical information amongst various stakeholders to report AEFIs

Lack of role clarity amongst stakeholders

Under and double reporting

Vaccine hesitancy amongst several groups in the population, made worse by misinformation campaigns regarding AEFIs

Lack of definitive information on the potential side effects making it hard for the regulatory bodies to quell misinformation campaigns about AEFIs

Furthermore, the credibility of the overall system is also vulnerable due to certain aspects of the AEFI, such as:

Vaccine hesitancy prevalent due to vaccine novelty, administration method, age related risks and some of the personal and social beliefs.

The presence of comorbidities making it difficult to ascertain whether an AEFI was coincidental or related to inoculation with the vaccine.

The frequency of coincidental adverse events based on gender, location, and age bound to increase considering the mass vaccination programs in large populations

Quality defects in vaccines due to manufacturing or distribution related issues. 

Strong processes in AEFI monitoring and reporting and processes would be needed to rectify these issues. As always, in public health matters, the pros and cons have been carefully weighed and the pros of vaccination outweigh the few adverse events reported about the vaccines. Yet, the immunization safety and vaccine pharmacovigilance efforts must continue to ensure that the vaccine is safe to administer and that the processes provide results to a high degree of credibility and reliability.



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