VACCINES IN HUMAN LIFE

 Vaccines in human life

VACCINES IN HUMAN LIFE

While humans believe and boast of independence, they are the ones in dire need of support for their basic living and progress. No other species –be they animals or plants need being defended by others for basic living. One such defence for humans against diseases is the vaccine. Vaccines are not curatives, but, they can arm the humans against potential infection by triggering the latter’s immune system to a state of readiness to identify and eliminate specific disease-causing invaders – the pathogens. The pathogens are either bacteria or viruses or fungi. Of them the most rapid to spread are the viruses; thus any fast-spreading event is described “viral” in social par lance. Therefore, any virus-induced disease can quickly spread among human hosts.  The present pandemic – the COVID, is a case in point.  Literally COVID transcends all barriers and for over a year has crippled world economy, even as it robbed off millions of life. Such catastrophic situations render humans vulnerable to death. 

While antibiotics can cure us of infectious bacterial diseases, they are of no avail in viral and fungal infections. Also, vaccines are essential to ward off crippling disorders and deadly situations. Maintaining a human population protected from fatality is a matter of high priority.  In the current COVID-19 pandemic, institutions had to race against time to evolve a life-saving protective like a vaccine. As per W.H.O’s report some 200 vaccine candidates are under preparation on a global estimate. Some manufacturers availed of existing strategy of attenuated viral sources; some others availed of a new strategy of mRNA-based vaccine formulation.

Attenuated [inactivated form of a virus or weakened virus or parts thereof] virus –based vaccine delivers a set of proteins   [antigens] typical of the infecting pathogen. The host is tuned to develop specific antibodies [against the pathogenic antigens] which can destroy the viral assembly and protect the infected person from the prospect of fatal reactions. Vaccine developed using inactivated virus does not cause infection. Yet, their spike proteins [resemble those of the pathogen] act as antigens and trigger antibody production in the host. The host comes to have ‘memory’ of the virus .Along with antibodies, antibody-producing memory cells are also formed in the host. Such memory cells remain for a long time. Any later infection of the host, by the same pathogen, triggers antibody production by memory cells. Antibodies are very specific to antigens. So, vaccines can protect   only against diseases caused by specific pathogens and those by closely related pathogens [antigens].

A number of vaccines developed have relied on attenuated sources as a reliable tool in vaccine formulation. [The history of use of human Adenoviruses in vaccine development started in 1953].The antigen component in the vaccine mimics the pathogen and elicits antibody response from the host and also promotes the formation/ sustenance of memory cells in the host. Any subsequent infection by the pathogen fails to cause disease as the pathogen [antigen] is effectively neutralized by host antibodies. 

K.Raman