How does a Vaccine work against Viruses?

COVID-19 has been declared as pandemic by WHO at 11th March 2020. With more than 69.7 million cases worldwide and 1.58million approximate death worldwide death, it has been one of the tragic event in human history. With midst of the pandemic, everyone is hoping for vaccine against COVID-19. Ever wondered how a vaccine works against COVID-19.It all started In 1796, the scientist Edward Jenner injected material from a cowpox virusinto an eight-year-old boy providing him resistance against smallpox that was considered deadly at that time . The eight-year-old was inoculatedagainst the disease and this became the first ever vaccine.

But how did it work? To understand how vaccines function, we need to know its contents, types and working mechanism of vaccine