Which of the following statements is/are correct about vaccination that provides protection against an infectious disease? 1. It blocks the entry of the infectious agent into body. 2. It produces antibodies against infection. 3. It kills the infectious agent when it enters in the body.

Vaccination provides protection by training the immune system to recognize and respond to pathogens. Statement 1 is incorrect because conventional vaccines primarily elicit systemic immunity rather than blocking the initial entry of pathogens at mucosal surfaces [1]. While mucosal vaccines are being developed to prevent pathogen adherence and invasion, most current vaccines do not prevent the physical entry of the agent into the body [1]. Statement 2 is correct as vaccines stimulate B lymphocytes to produce specific antibodies (humoral immunity) that neutralize pathogens [3]. Statement 3 is correct because the immune system, once primed by a vaccine, deploys antibodies and cell-mediated responses (like T cells) to clear or kill the infectious agent upon entry [3]. Antibodies bind to antigens to block biological activity or facilitate pathogen destruction [3]. Therefore, vaccines function by producing antibodies and killing agents post-entry, making options 2 and 3 correct.

Sources

1. [1] https://www.nature.com/articles/s41541-025-01280-0
2. [3] https://pmc.ncbi.nlm.nih.gov/articles/PMC2730944/