Vaccination and Immunity

• Immunity comes from active or passive creation of antibodies after getting an infection.
• Vaccines cause an active immune response using weakened or dead pathogens or their parts to build immunity.
• Vaccines create an artificial active immune response.
• Without vaccinations, natural infections result in severe illness, recovery, or death.
• Recovering from an illness may still result in long-term health consequences.

Memory and Humoral Immunity

• Memory and humoral immunity are important for vaccines to work well.
• Initial exposure to a pathogen leads to IgM antibodies, followed by IgG.
• A second exposure, like after vaccination, prompts a stronger response with IgG first and less IgM.
• IgG promotes class switching, oxidation, and effective humoral immunity for immunological memory and fighting disease.

Childhood Vaccination

• Childhood vaccinations start at two months old.
• Vaccinations aim to prevent severe illness, maintain herd immunity, and reduce outbreaks.
• The American Academy of Pediatrics updates the recommended childhood vaccine schedule.
• Some vaccines are given at 2-6 months with boosters after one year.
• Some vaccines are delayed until after one year due to interference from passive immunity.
• Maternal antibodies from breast milk can block the MMR vaccine's effectiveness.

Additional vaccines

• More vaccines are available for those aged 11-18.
• The flu vaccine can be administered from six months and annually.

Vaccine Success

• The measles vaccine greatly lowered cases, severe illness, and deaths after approval.
• Measles outbreaks in the 1980s occurred among unvaccinated adolescents in dorms who only had one vaccine.
• Risk of complications like pneumonia and death from measles is much lower after vaccination.

Video Summary

• Vaccines trigger the adaptive immune system to create immunity.
• Vaccines safely show antigens to train the immune system to defend against infections.
• Live attenuated vaccines use weakened pathogens, like in MMR or BCG vaccines, prompting a strong immune response and possibly lifetime protection.
• Subunit vaccines use parts of a pathogen, such as HPV vaccines, that need adjuvants to wake up the immune system.
• Subunit vaccines are safer for weak immune systems but may not provide as lasting protection as live attenuated vaccines.
• Herd immunity occurs when more than one population is immune to a disease and stops infection by breaking chains of transmission.
• Herd immunity protects people who cannot receive vaccines.
• Falling vaccination rates can cause diseases, like measles, to reappear.
• Eradication of diseases like smallpox is possible through vaccination and herd immunity.

Vaccination Challenges in the USA

• Some people do not consider vaccinations as essential because they have not seen certain rare diseases.
• Some think the risks of vaccines outweigh the risks of infections.
• There are inaccurate reports of links between vaccines and disorders like autism.

Communicating Vaccine Information to Patients

• Discuss specific concerns about vaccines with patients.
• Provide an atmosphere for discussion to dispel falsehoods and establish trust is important to build trust.
• Provide accurate and accessible information to counter misinformation.
• Build bridges with patients through understanding, listening, and patience.

Fundamental Immunological Response to a Vaccine

• Vaccines cause similar immunological reactions even when the route of administration vary.
• The aim is to train the immune system to identify and fend off a pathogen without causing illness.
• This primes the immune system for future exposures to that pathogen.
• The innate and adaptive immune systems activate and establish a barrier against potential future infections by it.
• A vaccine has a version of the pathogen that can either not cause infection or is less likely to
• This form of the pathogen is seen as foreign by the immune system
• Antigen-presenting cells (APCs) like dendritic cells and macrophages, capture the antigen.
• They process it and put it on their surface through major histocompatibility complex (MHC) molecules.
• These cells interact with other immune cell types like T and B cells, within the nearest lymph nodes.
• T helper cells (CD4+ T cells) identify the antigen from APCs, and then become activated.
• T helper cells release cytokines which facilitate the activation of other immune cells including B cells, cytotoxic T cells (CD8+ T cells), and macrophages.
• Cytotoxic T cells can target and eliminate infected cells, particularly for pathogens that infect host cells.
• B cells activate once they find the antigen, and recognize the antigen directly through their B cell receptor (BCR).
• B cells differentiate into plasma cells to produce antibodies.
• IgM is the antibody that is initially produced, while IgG is delayed.
• IgM facilitates complement system activation and helps to neutralize the pathogen.
• IgG is effective at pathogen neutralization and can activate the complement system.
• IgG stays in the bloodstream and provides long-term immunity by circulating, ready to neutralize any future encounter with the pathogen.
• Memory B cells and memory T cells form after the initial reaction.
• Memory B cells and Memory T cells "remember" the antigen and stay within the body for years or lifetime.

Secondary Immune Response

• Memory B cells differentiate into plasma cells and produce large amounts of IgG during re-exposure.
• Upon re-exposure to the pathogen, the immune system to activate because of the presence of memory cells.

Process of Vaccinations

• Recognition of antigens by antigen-presenting cells.
• Antigens are processed by APCs with relevant peptides presented on MHC molecules.
• Activation of innate immune cells and secretion of pro-inflammatory cytokines.
• Presentation of antigenic peptides to CD4+ T helper cells via MHC class II molecules.
• Th cells help B cells by recognizing the same antigen and activating them through cytokine signaling.
• Activated cells turn into plasma cells, which are responsible for antibody.
• B cells initially produce IgM antibodies to provide a rapid immune response.
• Some B cells switch to producing IgG antibodies, which improves specificity.
• A subset of B cells becomes memory B cells, providing immunological memory.
• Memory B cells activate upon re-exposure to pathogens.
• Rapid antibody production occurs as cells differentiate into plasma cells.
• IgG antibodies dominate in the secondary response and neutralize better.

Role of Immunological Memory:

• Cells provide long-term defense against certain pathogens.
• Faster and stronger response facilitated due to memory cells.
• Prevention of disease development, memory antibodies neutralize pathogens before they cause infection