The vaccines mentioned in the universal immunization sched-ule are selected on the basis of economic considerations and the epidemiology of infectious diseases in the region. But there are many vaccines available, which can be used to supplement the schedule depending on the individual cases and affordability.
Hepatitis B virus (HBV) is transmitted from one person to another through blood and body fluids, and primarily infects the liver. Healthcare workers and others exposed to infected blood or body fluids are at high risk for infection. Worldwide, it is most commonly spread to infants by their infected mothers. Approximately 90% of infants who are infected from their mothers at birth, and between 30% and 50% of those infected before age of 5 years, become chronic HBV carriers, while peo-ple who are newly infected as adults have only a 6–10% risk of chronic infection. For these reasons, hepatitis B immuniza-tions are recommended for routine administration at birth.
· Vaccination with at least three doses of the hepatitis B vaccine is recommended.
· All newborns should receive a dose of hepatitis B vaccine at birth.
· For children between the ages of 6 weeks and 7 years, HBV in combination with the DTP and inactivated polio vaccines may be given.
· HBV and Hib (Haemophilus influenzae type b) conjugate vaccine may be given to children between the ages of 6 weeks and 15 months.
Dialysis patients and immunocompromised people may require additional doses.
Measles vaccine is usually given with the mumps and rubella vaccines in children 12–15 months of age and older.
· Two doses of MMR vaccine are recommended for all children on or after the first birthday, including those who previously received the monovalent measles vaccine.
· The first dose is generally given at 12–15 months of age, and the second dose is generally given at 4–6 years of age. There must be a minimum of 4 weeks between the two doses.
· The second dose of MMR vaccine provides an added safeguard against all three diseases, but is recommended primarily to prevent outbreaks of measles.
Students who are exposed to an outbreak but have not already received two doses of the vaccine and who do not have other proof of immunity may be excluded from school for the entire duration of the outbreak or are required to receive the measles vaccination. The second dose of the measles vaccine series is effective when given as early as 1 month after the first dose, and this schedule is used when protection is needed quickly. Ninety-five percent of those who receive the MMR or monovalent measles vaccine at 12 months of age or older become immune after the first dose. After the second dose, 99.7% of those immunized are protected. Immunity is lifelong.
There are hypotheses that the MMR vaccine causes autism. However, the best available science indicates that the develop-ment of autism is not related to the use of the MMR or any other vaccine. One small study seemed to postulate such a link, but has subsequently been disproved by many other larger studies. Ten of the thirteen authors of that study later retracted from their suggestion of a link between MMR vaccine and autism.
Two newer vaccines, recently, have replaced the older vaccine used in typhoid fever. These vaccines are:
· an oral live attenuated vaccine using a weakened strain of Salmonella Typhi that is given orally and
· a parenteral capsular polysaccharide vaccine that is given by injection.
The oral typhoid vaccine can be administered to children 6 years of age or older and to adults. It is given in a total dosage of four capsules, one capsule taken orally every other day. A booster dose is needed every 5 years for people who continue to remain at risk.
The polysaccharide typhoid vaccine is given by injection to children older than 2 years of age. One shot is enough to provide protection. A booster dose is needed every 2 years for people who remain at risk for exposure.
The efficacy of the two licensed vaccines ranges from 50% to 80%. The oral vaccine has shown a protective efficacy of 62% for at least 7 years after the last dose.
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