Childhood Immunizations
Spring - 2016
Vaccination is a medical manipulation during which certain antigen of the infectious agent is being administered into the organism to induce the primary immune response. The first contact with the antigen is being accompanied by activation of the immune system and the emergence of a subpopulation of lymphocytes, which are able to specifically recognize the antigen. As a result, during the contact with the infectious agent, the immune system is able to react faster. While the purpose of vaccination is the prevention of disease, it can still occur, but in less severe form and with minimal complications. Mass vaccination significantly decreased mortality from infectious diseases during the last century. According to the WHO, vaccination saves up to three million lives every year and could save more, if it would completely cover the world's population (WHO, 2016). Besides that, elimination of the smallpox virus is the best result of the vaccination and had become an original monument to the Edward Jenner.
Vaccines can be divided into several groups according to their content. When the infectious agent, administered to the body is alive, the vaccine is called attenuated. The infectious agent in it lost its virulence. On the other hand, it is capable of replication that leads to the emergence of a sustainable and long-term immunity (Baxter, 2007). However, there is always a low risk of virulent properties returning, so this type of vaccines may not be used in patients with immunodeficiency states. The vaccines which contain inactivated infectious agents cause less lasting immunity because inactivated infectious agents are unable to replicate. Virus-like particles and subunit vaccines are similar because they both don’t contain pathogen’s DNA or RNA and a large number of molecules that form the pathogen in addition to antigenic molecules. They differ by their immunogenicity, which is lower than for cellular vaccines (Baxter, 2007). By the ways of administration, vaccines may be oral, nasal, intradermal, subcutaneous, intramuscular and intravenous. By the number of antigens, vaccines can be combined or mono-vaccines.
Child immunization is the most important link of all vaccination method. Because children's immune system is immature, they have the greatest risk of death from infectious diseases among all age groups. In addition, the immaturity of all child organism makes diseases more severe, especially in the first year of life, when children are not able to produce their own immunoglobulins. This is why in the majority of countries children are vaccinated at public expense and necessarily. The most common and frequently used vaccines are hepatitis B, rotavirus, diphtheria, tetanus, pertussis, poliovirus, pneumococcus, Haemophilus influenza, influenza, varicella, hepatitis A, measles, mumps, and rubella. In the USA, vaccination schedules are elaborated by the Centers for Disease Control and Prevention (CDC, 2016).
Vaccination against measles, mumps and rubella are being carried out with combined MMR vaccine. It contains attenuated pathogens of the three diseases, which is being administered by subcutaneous injection twice. The first dose should be injected in the interval from twelve to sixteen months. Second dose administration is being carried out between four and six years. It is crucial for a child to be vaccinated before attending the school. If the child is going to travel outside the United States, the first dose should be administered starting from the age of six months (CDC, 2016).
Immunization to hepatitis B is very important from the first moments of child’s life because during the birth there is a high risk of being infected from the mother. If so, rapid vaccination against hepatitis B prevents the development of disease in a child, lowers risk of synchronization and mortality rate. According to the schedule, the first dose is administered after birth, second dose - between one and two months. The third dose can be given between six and eighteen months (CDC, 2016). The vaccine is administered by intramuscular route.
A vaccine against rotavirus helps to avoid this intestinal infection in children. There are two vaccines against this infection, which differ by a number of doses. RV1 vaccine should be administered twice: at the age of two and four months. RV5 vaccine should be given one more time at six months (CDC, 2016). It is an attenuated vaccine, which is administered orally.
While rotavirus infection even in unvaccinated children commonly occurs easily and rarely leads to death, pertussis, diphtheria, and tetanus are very dangerous diseases, even for adults. To protect children from them is used a combined vaccine, called DTaP. It contains tetanus and diphtheria anatoxines and acellular pertussis antigen. Anatoxin is a molecule of toxin, which artificially lost its toxic properties. There is also a variation of the vaccine, calles DTP, which uses inactivated pertussis cells. However, the acellular vaccine is considered safer for infants. DTaP is used in five doses at the age of two, four, six, fourteen to eighteen months and between four and six years, followed by administration of Tdap vaccine at 11-12 years of age (CDC, 2016). Such high frequency of vaccine administration can be explained by the short duration of the antitoxic immunity. This vaccine is administered intramuscularly.
Haemophilus influenzae type b is a dangerous infection, which often causes purulent infections (meningitis, pheumonia) in young children. Streptococcus pneumoniae is also a threatening pathogen for infants, which causes upper respiratory tract infections and pneumonia. Vaccines against these two infections are very similar. The vaccines are called Hib and PCV13. Both vaccines are conjugate vaccines, which means that during their production a polysaccharide antigen of the bacteria was linked to a protein to potentiate its immunogenic properties. The route of administration is intramuscular. Immunization schedule is the same for Hib and PCV13. First, two doses are administered at two and four months. Next two (or one) doses are administered at six months and between twelve and fifteen months (CDC, 2016). The vaccines can be combined with DTaP and hepatitis B vaccine.
Inactivated poliovirus vaccine (IPV) is administered intramuscularly at two, four and between six and eighteen months. The last dose is given between four and six years. Annual vaccination against influenza should be started at the age of six months. Vaccination against varicella is being completed is two doses: between twelve and fifteen months and between four and six years. Hepatitis A immunization starts at the age of one yaer and should be finished before the two years of age (CDC, 2016).
While all recommended vaccines are repeatedly tested for security, they all considered safe for the vast majority of people. Sometimes they can cause mild local reactions or flu-like symptoms after administration. The most dangerous complication, which can arise from the vaccination is anaphylaxis. However, it mostly happens not because of the antigens of the vaccine, but due to the allergic reaction to preservatives used in the vaccine (CDC, 2016). Also, atenuated vaccines are contraindicated in patients with immunodeficiency states, because they can regain their virulence properties and cause disease.
References
Baxter, D. (2007). Active and passive immunity, vaccine types, excipients and licensing. Occupational Medicine, 57(8), pp.552-556.
Centers for Disease Control and Prevention (2016). Birth-18 Years Immunization Schedule Retrived from: http://www.cdc.gov/vaccines/schedules/hcp/imz/child-adolescent.html
Centers for Disease Control and Prevention (2016). Vaccines: Vac-Gen/Side Effects. Retrived from: http://www.cdc.gov/vaccines/vac-gen/side-effects.htm
World Health Organization, (2016). Retrived from: http://www.who.int/immunization/monitoring_surveillance/global_immunization_data.pdf
