The webpage for the Advisory Committee on Immunization Practices (ACIP) provides information on upcoming meetings, specific vaccine working groups, a list of all committee members and the committee’s recommendations.
Immunology is an incredibly complex field of medicine, so this explainer from the British Society of Immunology is especially helpful in describing in detail how the immune system responds to viruses.
In addition to their explainer on how the immune system responds to viruses, the British Society of Immunology has a separate explainer diving into the immune system’s response to bacteria.