Immunization

Passive Immunization

Passive immunization can be exogenously administered (artificial) or transferred from mother to fetus (natural).

Learning Objectives

Describe how artificial and natural passive immunity function to provide antibody protection against microorganisms

Key Takeaways

Key Points

  • Passive immunization provides humoral immunity.
  • Artificial passive immunization is the injection of preformed antibody solution when a patient is incapable of producing antibodies fast enough to combat a disease.
  • Natural passive immunization is the transfer of antibodies through the placenta of a pregnant woman to the fetus. Immunity lasts for a couple of months after the baby is born, after which active immunization is required.

Key Terms

  • in utero: Occurring or residing within the uterus or womb; unborn.

There are two types of passive immunity: artificial and natural. Artificial passive immunity is achieved by infusion of serum or plasma containing high concentrations of antibody. This form of passive immunity provides immediate antibody protection against microorganisms such as hepatitis A by administering preformed antibodies. These antibodies have been produced by another person or animal that has been actively immunized, but the ultimate recipient has not produced them. The recipient will only temporarily benefit from passive immunity for as long as the antibodies persist in their circulation.This type of immunity is short acting, and is typically seen in cases where a patient needs immediate protection from a foreign body and cannot form antibodies quickly enough independently.

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Immunity: Natural immunity occurs through contact with a disease causing agent, when the contact was not deliberate, where as artificial immunity develops only through deliberate actions of exposure. Both natural and artificial immunity can be further subdivided, depending on the amount of time the protection lasts. Passive immunity is short lived, and usually lasts only a few months, whereas protection via active immunity lasts much longer, and is sometimes life-long.

Passive immunity can also be acquired naturally by the fetus due to the transfer of antibodies by the maternal circulation in utero through the placenta around the third month of gestation. Immunity in newborn babies is only temporary and starts to decrease after the first few weeks, or months. Breast milk also contains antibodies, which means that babies who are breastfed have passive immunity for longer periods of time. The thick, yellowish milk (colostrum) that is produced during the first few days after birth is particularly rich in antibodies. For the newborn to have lasting protection, active immunity must be received. The first immunisation, given when a baby is two months old, includes whooping cough and Hib (haemophilus influenza type b) because immunity to these diseases decreases the fastest. Passive immunity to measles, mumps and rubella (MMR) usually lasts for about a year, which is why the MMR is given just after the baby’s first birthday.

Vaccination

Vaccination is a proven way to prevent and even eradicate widespread outbreaks of life-threatening infectious diseases.

Learning Objectives

Describe how active immunity to diseases can be acquired by natural exposure or by vaccination

Key Takeaways

Key Points

  • Immunization is the administration of antigenic solution, usually orally or via injection, to protect against infectious bacterial and viral diseases.
  • Vaccinations are usually given at specific ages and dates as per the recommended schedule provided by The Center for Disease Control.
  • Vaccines stimulate the body to produce antibodies without manifesting clinical signs and symptoms of the disease in immunocompetent hosts.

Key Terms

  • toxoids: bacterial toxins whose toxicity has been inactivated or suppressed.
  • immunity: the state of being insusceptible to a specific thing.
  • immunocompetent: Having a functioning immune system.

Active immunity to diseases can be acquired by natural exposure (in response to actually contracting an infectious disease ) or it may be acquired intentionally, via the administration of an antigen, commonly known as vaccination.

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Vaccination:: a child receiving an oral polio vaccine.

Vaccination has proven to be an effective way to stimulate the human body’s natural ability to produce antibodies, without contracting the disease and suffering any of its effects. This is also known as ‘acquired’ resistance.

The various antigenic materials used in these vaccinations (or immunization) may be of animal or plant origin. Some vaccinations are composed of live suspensions of weak or attenuated cells or viruses, deadened cells or viruses, or extracted bacterial products such as the toxoids used to immunize against diphtheria and tetanus.

Vaccinations are developed to stimulate the body’s production of antibodies without the manifestation of clinical signs and symptoms of the disease in immunocompetent hosts. Moreover, active immunization should cause permanent antigenic memory or lifelong immunity.

Vaccinations are usually given at specific ages and dates according to the recommended schedule provided by The Center for Disease Control. Sometimes booster vaccinations are needed to provide additional immunity in certain individuals and in certain cases.

Once your immune system has been trained to resist a disease, you are said to be immune to it. Before vaccines were developed, the only way to acquire immunity to a disease was to actually get it and, with luck, survive it. Even today, the risk of contracting some of these infectious diseases, like measles and chicken pox, can have devastating, long-term complications, like blindness.

Despite some of the various controversies surrounding vaccines over the years, the tiny proportion of risk is far outweighed by the numerous benefits. Certain infectious diseases, such as Smallpox, have been completely eradicated. Global mass vaccination drives have met with enormous success in reducing the incidence of many diseases.

Another consideration is that the newer vaccination programs also protect older age groups. By these vaccinated children not contracting these diseases, their parents, grandparents, friends and relatives (not vaccinated against these diseases themselves) will also be protected.

Development of New Vaccines

New vaccines are being developed to control recent infectious disease epidemics and cancers.

Learning Objectives

Describe how new vaccines are being developed to help eradicate several infectious global diseases

Key Takeaways

Key Points

  • The World Health Organization (WHO) oversees the development and distribution of vaccines for underdeveloped countries.
  • Vaccines for rotavirus diarrhea, pneumococcal disease, and meningococcal infections have been licensed and are approved for development.
  • Vaccines for cancer treatment are gaining traction and are based on training the body to recognize cancer cells as foreign.

Key Terms

  • vaccine: a substance given to stimulate the body’s production of antibodies and provide immunity against a disease, prepared from the agent that causes the disease, or a synthetic substitute.
  • immunization: the process by which an individual is exposed to a material that is designed to prime his or her immune system against that material.

National Immunization Programs

The implementation of large-scale, comprehensive national immunization programs, and the considerable successes that were achieved in the eradication of smallpox and the reduction of polio, measles, pertussis, tetanus, and meningitis, were among the most notable achievements of the 20th century. Even in the poorest countries, immunizations have been able to achieve significant progress in disease control. There is good reason to expect that these advances will be sustained and will progress even further in the 21st century.

Vaccines for Infectious Diseases

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Human papillomavirus vaccine: Gardasil is a human papillomavirus vaccine on the market and it protects against HPV-16 and HPV-18 which cause 70% of cervical cancers, 80% of anal cancers, 60% of vaginal cancers, and 40% of vulvar cancers.

A number of new vaccines with major potential for controlling infectious diseases have just been licensed or are at advanced stages of development. Among the illnesses targeted are rotavirus diarrhea, pneumococcal disease, and cervical cancer (as caused by human papillomavirus), which together kill more than a million people each year, most of them in developing countries.

In addition to these efforts against global diseases, progress is being made on a vaccine for the regional menace posed by meningococcal meningitis serogroup A, which causes frequent epidemics and high death rates and disability in African countries south of the Sahara. Continuing intensive efforts are under way to develop effective vaccines for AIDS, malaria, tuberculosis, dengue, leishmaniasis, and enteric diseases, among others and to adapt new technologies to improve formulation and delivery. The World Health Organization (WHO) facilitates the development of vaccines against infectious diseases of major public health importance, helps improve existing immunization technologies, and ensures that these advances are made available to the people who need them the most.

Vaccine Safety

Vaccines carry risks, ranging from rashes or tenderness at the site of injection to fever-associated seizures.

Learning Objectives

Describe the possible side effects of vaccine administration

Key Takeaways

Key Points

  • Vaccines can cause side effects in immunocompromised people, and allergic reactions due to the ingredients used to make them stable.
  • Side effects from vaccines are rare and most reported ailments after vaccination have not been proven to be caused by vaccination (e.g. autism, asthma).
  • Researchers continue to ameliorate vaccines composition making them safer and effective.

Key Terms

  • convulsion: An intense, paroxysmal, involuntary muscular contraction.
  • subunit vaccine: a vaccine that presents an antigen to the immune system without introducing viral particles, whole or otherwise
  • limpness: Property of being limp.

Vaccines are biological products with biological effects. Vaccines are made with a variety of ingredients including antigens, stabilizers, adjuvants, and preservatives; they may also contain residual by-products from the production process. These might be the cause of allergic reactions and side effects.

Vaccines carry risks, ranging from rashes or tenderness at the site of injection to fever-associated seizures called febrile convulsions and dangerous infections in those with compromised immune systems. Technological advances have made modern vaccines purer and safer than their historical counterparts. Most developed countries have switched to the inactivated polio vaccine and stopped using whole-cell pertussis (whooping cough) vaccines, which are made from killed bacteria and cause relatively high rates of arm swelling, febrile convulsions and periods of limpness or unresponsiveness.

Researchers have long known that some individuals are more susceptible to vaccine risks than others. Immunocompromised individuals have generally been discouraged from receiving live-virus vaccines. Some speculate that children with metabolic disorders might be prone to vaccine side effects. Safer vaccines and manufacturing processes are also in the works. New influenza vaccine doses are produced in cell culture, rather than the industry-standard chicken eggs. This process will improve reliability and reduce allergic reactions to egg proteins. Researchers are also developing replacements for vaccines that can be risky for vulnerable groups. These include current smallpox vaccines that cannot safely be given to immunocompromised people; the tuberculosis vaccine, which is not recommended for HIV-positive infants; and the yellow-fever vaccine, which puts elderly people at particular risk of a yellow-fever-like illness. Researchers are quick to emphasize that the benefits of vaccines still greatly outweigh the risks.

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Preparation of Measles Vaccine: Workers preparing measles vaccine in chicken eggs.