According to the predicted impact after varicella vaccination of children on Herpes Zoster from mathematical models, zoster cases are expected to increase until 20 years of vaccination. After that, zoster cases would decrease gradually and reach the same number of cases after 40 years of vaccination. Thereafter, the incidence rate is expected to decrease significantly and become a rare disease decades later. Currently, it is recommended for all adults US-born after 1980 who do not have evidence of immunity to varicella to receive 2 doses of varicella vaccine. Decades later, if all adults have evidence of immunity to varicella after vaccination in childhood, varicella vaccination recommendations would only need 1st dose at 12-15 months and 2nd dose at 4-6 years.
A therapeutic vaccine is one in which is used after infection occurs, aiming to induce immunity to alter the course of disease. Although vaccines are mostly prophylactic but in the recent years there have been significant developments towards therapeutic vaccines for infectious diseases like AIDS and Tuberculosis, gastric ulcers, cancers and autoimmune diseases.
Research is ongoing to develop a therapeutic HIV vaccine that is designed to improve body’s immune response to HIV in a HIV positive person by ramping up immune system to find and kill HIV infected cells and by preventing or limiting HIV for making its copies. In this way, these vaccines would not only slow down progression of HIV to AIDS but also decrease viral load to a level that it makes less likely for patient to transmit HIV to others, thereby playing its part in control as well as prevention of disease.
Serogroup B Meningococcal vaccines present unique challenge for development because strategy used for other meningococcal vaccines (serogroups A, C, W, and Y) does not work for it. Vaccines for other serogroups induce an immune response against the polysaccharide capsule around the bacterium. However, the capsule polysaccharide of group B meningococcal bacteria is structurally similar to certain abundant human glycoproteins like NCAM. It is therefore not a suitable target due to risk of autoimmune damage through a mechanism called immune mimicry. The unique challenge to development of serogroup B meningococcal vaccine has two facets: the difficulty in developing a vaccine in general and specific challenge of creating a vaccine against a pathogen that mimics host molecules.
In 2000, the United States declared measles was eliminated (absence of continuous disease transmission for greater than 12 months) within the United States. However, we still see measles outbreaks in the United States because of measles outbreaks in some other countries came into the United States by international travelers and there were spreads of measles infection by unvaccinated people within United States communities.
Serotype replacement is an untoward effect of the widespread use of pneumococcal conjugate vaccines that has led to emergence of nonvaccine pneumococcal serotypes, termed as replacement strains. These vaccine related and non-vaccine serotypes include 6C, 19A, 15A, 15B etc. These new serotypes appear as colonizers of the nasopharynx and as a cause of pneumococcal disease both in vaccine recipients and in general population at large. Reduction in nasal carriage of PCV serotypes appears to create an ecological niche for non-vaccine serotypes. For example, Streptococcus pneumoniae type 19 emerged as a most common cause of pneumococcal disease in children and adults a few years after universal vaccination with PCV7 in USA. The very strain was then added to the PCV13. However, since introduction of PCV13, other emerging serotypes not contained in vaccine emerged. Examples include 15B, 23B etc.
Pneumococcal Conjugate Vaccine (PCV)
Pneumococcal Purified Polysaccharide Vaccine (PPSV)
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