1. Vaccines are among the safest medical tools but require strict safety monitoring due to their administration to healthy populations including children. 2. Pharmacovigilance for vaccines differs from drugs in that adverse events are more complex due to multiple components, immunological actions, and difficulty determining causality for delayed events. 3. Reporting and evaluation of vaccine safety also differs in that vaccines are administered by primary care physicians who may lack technology and training in pharmacovigilance compared to drug oversight.

1. [Downloaded free from http://www.ijp-online.com on Monday, June 21, 2010, IP: 202.53.15.35]
Letters to Editor
Pharmacovigilance in vaccines
Sir, which may result in administration error and hence has to be
Vaccines are among the safest tools of modern medicine dealt with differently.
that help in protecting against disease by inducing immunity. In 2. Different modes of causality assessment
all countries, routine immunization represents a fundamental There are some issues, which make evaluation of vaccines
service of the public health system, offering one of the most different from other drugs. Local or immediate adverse reactions,
cost-effective methods of reducing morbidity and mortality which occur due to administrative error and attenuated virus,
among children less than five. A lack of complete vaccine can be attributed with a degree of confidence but delayed
coverage increases the risk of disease for the entire population. events are difficult to correlate. They have immunological
Pharmacovigilance is the science related to the safety of drugs considerations in addition to pharmacological action and take
and it helps prevent harmful effects of the drugs in population. a long time to respond.[4] Criteria commonly used to determine
It originated with thalidomide tragedy that caused 10000 birth causality such as resolution of the event following treatment
defects in children. Regulatory systems were established soon discontinuation and the result of re-challenge cannot be used
to bring an improvement in post-marketing surveillance for the to assess causality of an event occurring after vaccination.[5]
safer medicines.[1]
3. Reporters and reporting chain
Since the majority of vaccines are administered to a
Vaccines are a part of national health plan and physicians
vulnerable (children) as well as healthy population, a strict safety
involved in primary health care conduct the immunization en
supervision of vaccines is essential. Safety issues in vaccines
masse. So, reporter and reporting chain are different, especially
may lead to rumors and undermine a general confidence in
in developing countries where physicians involved in primary
vaccination and, ultimately, have dramatic consequences on
health care are not exposed to technology (internet, etc) and
immunization coverage and disease incidence.[2] Safety of
pharmacovigilance sensitization.
vaccines, therefore, must be excellent to make it acceptable,
Although pharmacovigilance of vaccines is important, yet
since it usually has a deferred individual benefit, but immediate
it is given much less attention. There are no different systems
adverse drug reactions (ADRs). Vaccine pharmacovigilance is
and regulatory guidelines in most of the countries for this
defined as the science and activities relating to the detection,
activity. Lot of research is going on for vaccine development in
assessment, understanding, prevention, and communication
infectious diseases e.g. HIV, malaria, H1N1, etc that have a high
of adverse events following immunization, or of any other
patient load. For the last two decades, pharmacovigilance has
vaccine- or immunization-related issues. The WHO defines an
been gaining an increasing attention. It is now, high time that
adverse event following immunization (AEFI) as “a medical
vaccines also receive their due attention.
incident that takes place after an immunization causes concern,
and is believed to be caused by the immunization.” The goal
Salil Budhiraja, Raghuram Akinapelli
of vaccine pharmacovigilance is the early detection and timely Department of Pharmacovigilance and Drug Safety,
response to adverse events following immunization, in order to MakroCare, Hyderabad – 500 033,
minimize negative effects to the health of individuals and lessen Andhra Pradesh, India
the potential negative impact on immunization of population.
Although vaccines are considered to be medicines with Correspondence to: Dr. Salil Budhiraja,
anti-infective activity that work by immunological action and E-mail: salil_budhi@yahoo.co.in
administered for prophylaxis, pharmacovigilance for vaccines
should be different from other drugs because of the following
reasons. References
1. Information to be captured is complex and different from 1. Ronald DM, Elizabeth BA. The basis of Pharmacovigilance introduction. In: Ronald
other drugs. DM, Elizabeth BA, editors. Pharmacovigilance. 2nd ed., 2nd ed. Great Britain: John
Wiley Sons Inc; 2007. p. 1-3.
Vaccines are complex biological products, which may 2. Concept paper for a guideline on the conduct of pharmacovigilance for vaccines.
include multiple antigens, live organisms, adjuvants, and European Medicines Agency. 2005. Available from: http://www.emea.europa.eu/
preservatives. ADRs may be due to administration of live wild pdfs/human/phvwp/37200405en.pdf. [accessed on 2009 Dec 1].
viruses e.g. lymphocyte meningitis after anti-mumps vaccine 3. Autret-Leca E, Bensouda-Grimaldi L, Jonville-Béra AP, Beau-Salinas F.
or may be non-specific, related to a component different from Pharmacovigilance of vaccines. Arch Pediatr 2006;13:175-80.
4. Clajus C, Spiegel J, Bröcker V, Chatzikyrkou C, Kielstein JT. Minimal change
the antigen (aluminum hydroxide involved in the "macrophagic nephrotic syndrome in an 82 year old patient following a tetanus-diphteria-
myofasciitis," allergic reactions to neomycin, latex, egg, or poliomyelitis-vaccination. BMC Nephrol 2009;10:21.
gelatin).[3] So, each component has unique safety implications, 5. WHO. Adverse Events Following Immunization (AEFI): Causality Assessment.
which require different information to capture as compared World Health Organization. Available from: http://whqlibdoc.who.int/aide-memoire/
to other drugs. In a vaccination campaign, the vaccine is a87773_eng.pdf. [accessed on 2009 Dec 14].
administered to a large population over a short period of time, DOI: 10.4103/0253-7613.64488
116 Indian J Pharmacol | April 2010 | Vol 42 | Issue 2 | 115-118