Epidemiological and Environmental Factors on Immunity and Diseases – Role of Vaccination

This article tries to highlight the past, present and future trends of emergence of Infectious Diseases.  Elucidation of origins of emerging infectious threats, recent patterns of disease emergence and future disease pattern will enable early detection and response in the event of an outbreak. It will also predict its occurrence especially in Indian scenario. 
Infections, transmissible OR communicable diseases usually occur in the presence and growth of pathogens. The body of the host is the area where symptoms and sign will appear, however infectivity is the ability of an organism to infect, incubate and multiply. But there are occasions transmission of pathogen and also been inhibited or disappeared by epidemiological or environmental factors. 
This article throws light on how some diseases have become extinct whereas some others have changed in aetiology. The present Pandemic of COVID-19 (Novel Corona Virus) has made all of us to ponder on ways of preventing and increasing immunity towards it.  This article tries to highlight the Pros and Cons of the vaccine as a preventive treatment and also discusses about the “hygiene hypothesis” especially applicable to the first world countries where the virulence and infectivity of Corona has been much more than the third world countries.