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OPTIONAL VACCINES

Hemant Patel*, Mahesh Balsekar**

*Family Physician; **Paediatrician, Mumbai.

What are the additional vaccines recommended by the IAP?

The routine immunisation schedule includes the following vaccines BCG, oral polio vaccine, triple antigen, measles and the MMR vaccine. The IAP has recommended the following additional vaccines as optional. Of these it has been recommended that the Hepatitis B and typhoid are to be recommended actively. The other vaccine i.e. Hib, hepatitis A and the chicken pox vaccine are not recommended actively but on an optional basis.

H. INFLUENZAE TYPE B VACCINE

1. Is the (haemophilus influenzae type b) Hib infection common in India?

Invasive Hib Infection has a reported prevalance of 40-80/1,00,000. There is insufficient data regarding the prevalence of Hib infections in India. Invasive Hib infection includes primarily epiglottitis, pneumonia and meningitis. The diagnosis of epiglottis is primarily clinical. It is the opinion of most paediatricians that epiglottitis is relatively uncommon in India compared to western countries. Pyogenic meningitis is seen in India but the incidence of Hib meningitis was thought to be low. Recent data suggests that the prevalence of Hib has been underestimated due to a lack of adequate microbiological facilities. With proper microbiological studies, it is estimated that up to 30% of meningitis cases are due to Hib infections. Similarly, it is believed that the role of Hib infections in childhood pneumonias has been underestimated. Hence it appears that though Hib infections are definitely lower in India compared to western countries, its prevalence has been underestimated.

2. Is there any effective treatment for Hib Infection?

Despite early and appropriate treatment, meningitis has a 5-10% mortality. The morbidity is similarly considerable. 10-20% have serious neurodevelopmental sequelae and as many as 5-20% have hearing impairment and upto 50% have subtle neurodevelopmental morbidity. With delayed diagnosis, the outcome would be even worse.

3. Does the IAP still recommend the Hib Vaccine?

The IAPís has recommended that the Hib vaccine be included as an optional vaccine for two reasons. There is insufficient epidemiological data to support its routine use and the fact that the vaccine is expensive. Hib infections are serious but easily prevented by the vaccine. For many, cost is not a constraint. In such families, a lack of epidemiological data is not sufficient grounds to deprive vaccination. Hence the vaccine is kept as an optional vaccine.

4. Is it wrong to not vaccinate children with Hib Vaccine?

There are inadequate epidemiological studies regarding the prevalence of Hib infections in our country. Till such studies confirm the need for routine Hib vaccine in our country, it need not be considered an essential or compulsory vaccine. Hib vaccine may however be offered as an optional vaccine to those who can afford the vaccine.

5. What is the schedule of vaccination?

a) The primary vaccination schedule consists of three doses administered at intervals of 1 to 2 months in the first 6 months of life, can start from the age of 2 months. A booster is recommended in the second year of life.

b) Infants between the ages of 6 and 12 months previously unvaccinated should receive 2 injections one month apart followed by a booster in the second year of life.

c) Previously unvaccinated children aged 1-5 years should be given one dose of vaccine.

VARICELLA VACCINE

1. What is the role of varicella vaccine in preventing chicken pox in the prediatric population?

The varicella vaccine is a safe vaccine and studies have confirmed that it is effective in preventing chicken pox for up to 20 years after vaccination. Some countries like USA have recommended universal immunisation with the varicella vaccine between 12-18 months. They hope to achieve a 95% coverage within 5 years. With such a strategy, over the years, the infection rate of varicella would come down dramatically in the community.

A vaccination programme would have several advantages to the community* Prevents the disease safely and effectively* Prevents missing school due to the infection, which is particularly important during examinations.* Prevents chicken pox and its complications in pregnancy.* Reduces the likelyhood of Herpes Zoster in later life.

2. Are there any disadvantages in routinely vaccinating children with varicella vaccine?

In India, due to the high cost of the vaccine it would be difficult to vaccinate a large percentage of the children. If the vaccination cover is low, varicella infection would continue to occur in the community. In such a scenario there are concerns about the long term effect of vaccinating only a small percentage of children. In vaccinated persons, the exact duration of immunity is not known. If the vaccine immunity diminishes over a period of time, one might face a situation where adults might start getting the disease. In adults, as we know, infections are usually more severe. In India, chicken pox infection occurs mainly in early childhood. In young children, the disease is almost always mild, and the immunity after natural infection is lifelong. Therefore its prevention may not be absolutely necessary. Also, the vaccine is expensive and this is an important issue in a country like India.

3. Should we vaccinate our children with the vaccine?

Most countries do not vaccinate their children routinely with chicken pox vaccine. USA is one of the few countries which routinely advises the vaccine but most European countries do not. The Indian Academy of Paediatrics has recommended that its administration and its use is Ďoptionalí based on the preference of the family and their doctor.

4. What policy should we adopt regarding the Chicken Pox vaccine?

In practical terms the vaccine can be administered above 1 year. At this age its use is optional : single dose. Most paediatricians in India recommend the vaccine actively at 10 years i.e. only to children who have not yet had an attack of chicken pox in the past, recommended two doses 4-8 weeks apart.

By 10-12 years a large percentage of children will already have had the disease and will develop lifelong immunity. Those who have not had the infection will be vaccinated at 10-12 years. This will prevent more severe forms of disease which occur in adolescents and adults.

HEPATITIS A VACCINE

F. Is Hepatitis A major problem in children?

Hepatitis A in children, the infection is almost always mild. In infants and children under 5 years, most infections occur without symptoms or with mild symptoms. Children who get infected after the age of 5 years, particularly 10 years, are more likely to develop jaundice and complications/severe disease. Natural infection results in lifelong immunity.

2. In that case is vaccination with Hepatitis A vaccine necessary?

No country in the world as yet routinely advises Hepatitis A vaccine.This is because:# The vaccine is expensive.# Hepatitis - A is a common infection but the disease is usually mild and the complication rate is low.

3. In that case should we advise the Hepatitis A vaccine in India?

Hepatitis A is common in our country. In India, traditionally Hepatitis A infection occurs mainly in young children. In most cases, the infections occur without any symptoms or as a mild disease. In Mumbai, 2 out of 3 children between the ages of 5-10 years are already infected and therefore immune from the disease.

Over the years, the level of hygiene has improved and children no longer get infected with Hepatitis A. As a result infection occurs at higher rates in adults. In adults, as we know infections are usually more severe. It is believed that the incidence of infections in adults might increase in the years ahead. For this reason, there is a basis for vaccinating children in India. The Indian Academy of Paediatrics does not advise Hepatitis A as a part of our immunisation schedule and its use is optional. The decision is left to the individual family and doctor.

4. If we decide to administer Hepatitis A Vaccine at what age should it be administered?

Hepatitis A vaccine can be administered at any time beyond 1 year. However the exact duration of immunity after vaccination is not known but expected to be at around 20 years. If children are vaccinated at a young age, e.g. 1-2 years, the disease would be prevented for 15-20 years. There are concerns that if immunity diminishes over a period of time, infections could then occur in adulthood, where infections are usually more severe than in childhood.

For this reason many paediatricans recommend the vaccine for children above 5 years. In India, 2 out of 3 are already infected by age 5. Infections under 5 years are almost invariably mild and give rise to lifelong immunity. Vaccination above the age of 5 years offers the benefit of preventing severe forms of infection, which usually occur after 5-10 years of age. Vaccination above 5 years is therefore considered a cost effective strategy in our country. Before immunising a child, one needs to do a blood test to determine if the child has already been infected with Hepatitis A virus. This is done by checking the blood for the presence of Anti HAV-IgG antibodies. If these are positive, it means that the child has already been infected and has protective antibodies. Immunisation is therefore unnecessary. On the other hand if the child is anti-HAV IgG antibodies negative, it means that vaccination is necessary.

Children and adolescents from 1 year upto 18 years of age should be given a single dose of 0.5 ml (720 units), but adults from 19 years onwards need a dose of 1 ml (1440 units), intramuscular. Followed by a booster dose anytime between 8 and 12 months after a single primary dose.

Q. Why does immunisation against measles require any additional dose over and above the usual dose at 9 month?

A. An additional dose of measles ensures better protection than the single dose, specially in topical country like ours. The additional dose may not be possible for mass scale immunisation but where feasible, should be given along with mumps and rubella in the form of MMR injection at 15 months of age.

Q. Why is Immunisation against mumps is necessary?

A. Though mumps is basically a benign viral disease- it involves the exocrine glands. Main complication is in the form of orchitis in male which may lead to sterility in adult life. Hence immunisation is definitely necessary against mumps.



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