The immune system is a complex network of specialized organs and cells protects the body from destruction by foreign agents and microbial pathogens , degrades and removes damaged or dead cells, and exerts a surveillance function to prevent the development and growth of malignant cells. The immune system is composed of immune cells and central and peripheral lymphoid structures. The immune cells move throughout the body, searching for and destroying foreign substances but avoiding cells regarded as self.
Natural immunity: It is not produced by the immune response. This type of immunity is present at birth and appears to be present in all members of a species. Acquired immunity: It develops after birth as a result of exposure to an antigen, thereby activating the immune response. Acquired immunity can be either active or passive, depending on whether the immune response took place in the host or a donor.
Differences of immune system of children and adult The normal human no fully active immune system at birth because of immaturity. It relies instead on passively transferred antibodies from the mother. This maternal antibody slowly decreases in concentration and for all practical purposes, has waned by 1 year. The infant own production of antibody begins to be meaningful at 7 or 8 months of age when the total of maternal and infant antibody is low. One has waned and the other is not up to full strength. This is age when many of the infectious disease processes of infancy begin /e.g. otitis media, pneumonia.
Administration of a substance to a person with the purpose of preventing a disease
Traditionally composed of a killed or weakened microorganism
Vaccination works by creating a type of immune response that enables the memory cells to later respond to a similar organism before it can cause disease
Early History of Vaccination
Pioneered India and China in the 17th century
The tradition of vaccination may have originated in India in AD 1000
Powdered scabs from people infected with smallpox was used to protect against the disease
Smallpox was responsible for 8 to 20% of all deaths in several European countries in the 18th century
In 1721 Lady Mary Wortley Montagu brought the knowledge of these techniques from Constantinople (now Istanbul) to England
Two to three percent of the smallpox vaccinees, however, died from the vaccination itself
Benjamin Jesty and, later, Edward Jenner could show that vaccination with the less dangerous cowpox could protect against infection with smallpox
The word vaccination, which is derived from vacca, the Latin word for cow.
Era of Vaccination
English physician Edward Jenner
observed that milkmaids stricken with a viral disease called cowpox were rarely victims of a similar disease, smallpox
Jenner took a few drops of fluid from a pustule of a woman who had cowpox and injected the fluid into a healthy young boy who had never had cowpox or smallpox
Six weeks later, Jenner injected the boy with fluid from a smallpox pustule, but the boy remained free of the dreaded smallpox.
Era of Vacinnation
In those days, a million people died from smallpox each year in Europe alone, most of them children.
Those who survived were often left with blindness, deep scars, and deformities
I n 1796, Jenner started on a course that would ease the suffering of people around the world for centuries to come.
By 1980, an updated version of Jenner vaccine lead to the total eradication of smallpox.
Early History of Vaccination
In 1879 Louis Pasteur showed that chicken cholera weakened by growing it in the laboratory could protect against infection with more virulent strains
1881 he showed in a public experiment at Pouilly-Le-Fort that his anthrax vaccine was efficient in protecting sheep, a goat, and cows.
In 1885 Pasteur developed a vaccine against rabies based on a live attenuated virus
A year later Edmund Salmon and Theobald Smith developed a (heat) killed cholera vaccine.
Over the next 20 years killed typhoid and plague vaccines were developed
In 1927 the bacille Calmette-Guérin (BCG vaccine) against tuberculosis vere developed
Since Jenner's time, vaccines have been developed against more than 20 infectious diseases
The date of introduction of first generation of vaccines for use in humans*
1927 Tuberculosis (BCG)
1935 Yellow Fever
After World War II
1955 Injectable Polio Vaccine (IPV)
1962 Oral Polio Vaccine (OPV)
1981 Hepatitis B
Vaccines have been made for only 34 of the more than 400 known pathogens that are harmful to man.
Immunization saves the lives of 3 million children each year, but that 2 million more lives could be saved if existing vaccines were applied on a full-scale worldwide
Human Vaccines against pathogens Immunological Bioinformatics, The MIT press.
Type of Vaccination
Type of Vaccination Live Vaccines
Able to replicate in the host
Attenuated (weakened) so they do not cause disease
Induce a broad immune response (cellular and humoral)
Low doses of vaccine are normally sufficient
Long-lasting protection are often induced
May cause adverse reactions
May be transmitted from person to person
Relatively easy to produce (not live)
Classically produced by inactivating a whole virus or bacterium
The vaccine may be purified
Selecting one or a few proteins which confer protection
Bordetella pertussis (whooping cough)
Create a better-tolerated vaccine that is free from whole microorganism cells
Subunit Vaccines: Polysaccharides
Many bacteria have polysaccharides in their outer membrane
Polysaccharide based vaccines
Generate a T cell-independent response
Inefficient in children younger than 2 years old
Overcome by conjugating the polysaccharides to peptides
Used in vaccines against Streptococcus pneumoniae and Haemophilus influenzae.
Subunit Vaccines: Toxoids
Responsible for the pathogenesis of many bacteria
Toxoid based vaccines
Traditionally done by chemical means
Altering the DNA sequences important to toxicity
Subunit Vaccines: Recombinant
The hepatitis B virus (HBV) vaccine
Originally based on the surface antigen purified from the blood of chronically infected individuals.
Due to safety concerns, the HBV vaccine became the first to be produced using recombinant DNA technology (1986)
Produced in bakers’ yeast (Saccharomyces cerevisiae)
Virus-like particles (VLPs)
Viral proteins that self-assemble to particles with the same size as the native virus.
VLP is the basis of a promising new vaccine against human papilloma virus (HPV)
In phase III
For more information se: http://www.nci.nih.gov/ncicancerbulletin/NCI_Cancer_Bulletin_041205/page5
Introduce DNA or RNA into the host
Coated on gold particles
Carried by viruses
vaccinia, adenovirus, or alphaviruses
bacteria such as
Salmonella typhi, Mycobacterium tuberculosis
Easy to produce
Induce cellular response
Low response in 1st generation
Type of Vaccination
Live attenuated Vaccine
Inactivated organism or their products
Pertussis( whole cell/acellular)
Pneumococcal Polysaccharide vaccine
Transfer of antibody produced by one human or other animal to another
Transplacental most important source in infancy
Sources of Passive Immunity
Almost all blood or blood products
Homologous pooled human antibody (immune globulin)
Homologous human hyperimmune globulin
Heterologous hyperimmune serum (antitoxin)
IMMUNOGLOBULIN PREPARETION Normal human Ig. Normal human Ig is an antibody-rich fraction, obtained from a pool of at least 1000 donors. The preparation should contain at least 90% intact IgG; it should be as free as possible from IgG aggregates; all IgG sub-classes should be present; there should be a low IgA concentration; the level of antibody against at least two bacterial species and two viruses should be ascertained Normal human Ig used to prevent measles in highly susceptible individuals and to provide temporary protection /up to 12 weeks/ against hepatitis A infection. Live vaccines should not normally be given for 12 weeks after an injection of normal human Ig.
Specific human Ig. These preparations are made from the plasma of patient who have recently recovered from an infection or are obtained from individuals who have been immunized against a specific infection. The advantages of Ig-s are: 1. freedom from hepatitis B 2. concentration of the antibodies into a small volume for intramuscular use. 3. stable antibody content, if properly stored.
Site of Administration Anterolateral aspect of the thigh in infants and deltoid muscle in older children or adult. Intramuscular Anterolateral aspect of the thigh or the upper arm Subcutaneous Over the insertion of left deltoid muscle Intradermal
Who should not be vaccinated?
Reactions to Previous vaccine
Simultaneous administration of Vaccines
A. Allergic Reactions to Egg-related antigens
Yellow fever and influenza vaccines do contain egg proteins and rarely induce immediate allergic reactions. Skin testing is recommended before administration with an history of allergic to egg
MMR- Even those with severe hypersensitivity are at low risk of anaphylaxis.
B. Antibiotic-induced allergic reaction
Delayed type local reaction 48-96 hours afterwards and is usually minor
IPV and OPV – streptomycin, neomycin and polymyxin B
MMR and varicella vaccine-neomycin
C. Alum - HA
D. Gelatin- MMR, Varicella vaccine
Low-grade fever or mild illness is not a contraindication for vaccination
Children with moderate or severe febrile illnesses can be vaccinated as soon as they are recovering and no longer acutely ill
Vaccination in Pregnancy
Risk to a developing fetus from vaccination of the mother during pregnancy is mostly theoretical
Only smallpox vaccine has ever been shown to injure a fetus
The benefits of vaccinating usually outweigh potential risks
Vaccination in Pregnancy
Vaccinate if indicated (hep B, Td, mening, rabies)
Vaccinate if benefit outweighs risk (all other)
Live vaccine – do not administer
Exception is yellow fever vaccine
OPV is Contraindicated
in household contact, in recipient ( asymptomatic or symptomatic)
IPV for these children and household contacts
MMR vaccination should be considered for all asymptomatic and to all symptomatic HIV-infected persons who do not have evidence of severe immunosuprresion or measles immunity
Pneumococcal vaccine, Hib, DTP (or DTaP), Hepatitis B vaccine, Influenza vaccines are all indicated
No live viral vaccines and BCG. IPV for these patients, their siblings and their household contacts
No live vaccine (except varicella) until six months after immunosuppressive therapy