Vaccination History Chapter 18 PDF

Pharmacy Chapter 18 History of Vaccines Microbiology II : Dr. Amin Omar : 1  History of Vaccination Variolation: inoculation of small amount of smallpox into skin (eighteenth century) Vaccination: – Inoculation of cowpox virus into sk...

Pharmacy Chapter 18 History of Vaccines Microbiology II : Dr. Amin Omar : 1  History of Vaccination Variolation: inoculation of small amount of smallpox into skin (eighteenth century) Vaccination: – Inoculation of cowpox virus into skin (Jenner) – Inoculation with rabies virus (Pasteur)  History of Vaccines Edward Jenner, who received variolation at 8 yrs, became a physician in 1798. Dairymaids, told him that they had no fear of smallpox because they had already had cowpox. Cowpox is a mild disease that causes lesions on cows 'udders; dairymaids’ hands often became infected during milking. Jenner inoculated people with cowpox in an attempt to prevent smallpox. Vaccination (from the Latin vacca, meaning cow) was coined. A vaccine is a suspension of organisms or fractions of organisms that is used to induce immunity. Two centuries later, the disease of smallpox has been eliminated worldwide by vaccination, and two other viral diseases, measles and polio, are also targeted. Jenner’s inoculations worked because the cowpox virus, which is not a serious pathogen, is closely related to the smallpox virus.  Principles and Effects of Vaccination The injection of cowpox, by skin scratches, provoked a primary immune response in the recipients, leading to the formation of antibodies and long-term memory cells. Later, when the recipient encountered the smallpox virus, the memory cells were stimulated, producing a rapid, intense secondary immune response. This response mimics the immunity gained by recovering from the disease. The cowpox vaccine was soon replaced by a vaccinia virus vaccine (mix of Cowpox and Small pox)  Many Bacterial communicable diseases can be controlled by behavioral and environmental methods. – For example, proper sanitation can prevent the spread of cholera infection. – Treated with antibiotics. Viral disease is controlled by Vaccination Herd Immunity : a phenomenon If most of the population is immune,, outbreaks are limited to sporadic cases because there are not enough susceptible individuals to support the spread of epidemics.  Types of Vaccines and Their Characteristics There are now several basic types of vaccine. 1. Live Attenuated Vaccines 2. Inactivated Killed Vaccines 3. Subunit Vaccines 4. Conjugated Vaccines 5. Nucleic Acid (DNA) Vaccines  1. Live Attenuated Vaccines More closely mimic an actual infection. As the pathogen reproduces within the host cells, cellular, as well as humoral, immunity usually is induced. Lifelong immunity, especially in the case of viruses, is often achieved without booster immunizations, and an effectiveness rate of 95% is not unusual. This long-term effectiveness probably occurs because the attenuated viruses replicate in the body, increasing the original dose and acting as a series of secondary (booster) immunizations. Chickenpox, Herpes zoster, Measles, Mumps, Rubella  2. Inactivated Killed Vaccines Use microbes that have been killed, usually by formalin or phenol. Generally speaking, these vaccines are considered safer than live vaccines. Often require repeated booster doses. They also induce a mostly humoral antibody immunity, which makes them less effective than attenuated vaccines in inducing cellular immunity. A. Viral Vaccines – Include those against Hepatitis A, rabies, influenza, and polio (the Salk polio vaccine). B. Bacterial Vaccines: – pneumococcal pneumonia and cholera. – pertussis (whooping cough) and typhoid.  3. Subunit Vaccines Subunit vaccines use only those antigenic fragments of a microorganism that best stimulate an immune response. This avoids the dangers associated with the use of live or killed pathogenic organisms. Subunit vaccines include A. Recombinant vaccines that are produced by genetic modification techniques to produce the desired antigenic fraction. o For example, the vaccine against the hepatitis B virus consists of a portion of the viral protein coat that is produced by a genetically modified yeast.  B. Toxoids, which are inactivated toxins, are vaccines directed at the toxins produced by a pathogen o For example: The Tetanus and Diphtheria toxoids. The person requires a series of injections to attain full immunity, followed by boosters every 10 years. Diphtheria can be treated by: Toxoid Vaccine Antibiotics were available to treat, Antitoxins, that is, serum containing diphtheria antibodies against the toxin.  Antitoxins are also used in treatment of tetanus. It can provide protection against tetanus toxin when there is danger of tetanus and the patient has not had a current tetanus vaccination. C- Virus-like Particle (VLP) Vaccines: resemble intact viruses but do not contain any viral genetic material. – human papilloma vaccine consists of viral proteins produced by a genetically modified yeast. D- Polysaccharide Vaccines -Streptococcus pneumoniae – The vaccine used against pneumococcal targets the capsule which makes them resistant to phagocytosis. ▪ A vaccine for N. meningitidis a bacterial cause of meningitis uses a similar mechanism.  4. Conjugated Vaccines Deal with the poor immune response of children to vaccines based on capsular polysaccharides. The polysaccharides are combined with proteins such as diphtheria or tetanus toxoid; the two separate components chemically linked together create a stronger immune response This approach has led to the very successful vaccine for Haemophilus influenzae type b (Hib), which gives significant protection even at 2 months.  5. Nucleic Acid (DNA) Vaccines Based on injecting plasmids of “naked” DNA into muscle results in the production of the protein antigen encoded in the DNA. The protein antigens ❖ Stimulate both humoral and cellular immunity in red bone marrow ❖ They also tend to be expressed for extended times, with good immunological memory. Such vaccines would have particular advantages for the less developed parts of the world. Vaccines would not require refrigeration. Manufacturing operations for such vaccines are very similar for different diseases, which should lower costs. Table 18.1 Principal Vaccines Used in the United States to Prevent Bacterial Diseases in Humans Bacterial Diseases Table 18.2 Principal Vaccines Used in the United States to Prevent Viral Diseases in Humans Viral Diseases  Vaccines Used to Prevent Bacterial Diseases Disease Vaccine Diphtheria Purified diphtheria toxoid Meningococcal meningitis Purified polysaccharide from Neisseria meningitidis Pertussis (whooping cough) Inactivated toxin plus acellular fragments of Bordetella pertussis Pneumococcal pneumonia Purified polysaccharide from seven strains of Streptococcus pneumoniae Tetanus Purified tetanus toxoid Haemophilus influenzae type b Polysaccharide from Haemophilus influenzae meningitis type b conjugated with protein to enhance effectiveness  Vaccines Used to Prevent Viral Diseases Disease Vaccine Influenza Injected vaccine, inactivated virus (nasally administered: attenuated virus) Measles Attenuated virus Mumps Attenuated virus Rubella Attenuated virus Chickenpox Attenuated virus Poliomyelitis Killed virus Rabies Killed virus Hepatitis B Antigenic fragments of virus Hepatitis A Inactivated virus Smallpox Live vaccinia virus Herpes zoster Attenuated virus Human papillomavirus Antigenic fragments of virus Table 18.3 Recommended Immunization Schedule for Persons Aged 0–6 Years—United States, 2011 (CDC)  Vaccines for Persons Aged 0–6 Years 1) Hepatitis B 2) Rotavirus 3) DTaP 4) Haemophilus influenzae type b 5) Pneumococcal 6) Inactivated poliovirus Influenza 7) MMR 8) Varicella 9) Hepatitis A 10)Meningococcal Figure 18.1 Influenza viruses are grown in embryonated eggs.