Specific vaccines
What are vaccines?
Vaccines are biomedical products made from micro-organisms. Their purpose is to stimulate "active immunity", ie. to induce the body to build up resistance to infectious agents by learning to synthesize "antibodies", or by some other means.
There are three main types of vaccines:-
Live "attenuated" organisms
Killed organisms or components of organisms
Inactivated bacterial products called toxoids
How do they work?
We are born equipped with some basic defences against invasion by micro-organisms, but they are relatively slow and inefficient. When the body encounters a harmful bacteria or virus for the first time, if that organism is too virulent for our basic defenses (mainly some types of white blood cells) the organism becomes established and causes disease. To combat infectious diseases, the body must synthesize specific agents for dealing with the infecting organism. These can be humoral (antibodies) or cell-mediated. Once the body, has learned to produce a specific antibody it can then produce large amounts of the antibody, which is much more efficient at neutralising the invaders than non-specific defense. If these learning and production processes occur quickly enough, then the disease can be overcome. The next time the body encounters an organism which it has previously met, it "remembers" what to do to combat the infection, and the process becomes much more rapid, thus reducing the severity of the disease or prevent the disease altogether. The body is said to have "acquired immunity"
Vaccines induce immunity by the same principle. Vaccines bear some similarities to the disease agents. A vaccine introduced into the body provokes a defence response, but because the vaccine is virtually harmless, the body acquires immunity without suffering the disease.
Are vaccines safe?
In the West, concern over the safety of vaccines has been increasing for some years now, despite the fact that the quality of vaccines has been improving all the time. In Thailand, people are generally much less concerned about the question of safety. Problems associated with vaccines can be broadly divided into three categories:-
Common minor side effects. Moderate fever, some soreness at the site of injection are fairly common. The measles and MMR vaccines often cause fever. The DPT vaccine, if not given with good technique ie injected too superficially, often cause swelling and some pain. Such side effects are commonplace and usually do not mean that further doses of the vaccine cannot be given.
More severe side effects clearly caused by the vaccines. These are rare and include allergic reaction to components of the vaccine eg egg allergy and MMR, fever greater than 39.5C or for longer than 48 hours, large painfull swelling at the injection site. Although allergic reaction to vaccines is unpredictable and potentially fatal, it is extremely rare and in most countries fatal reaction has never been reported.
Severe side effects which have been associated with vaccination but for which there is no good evidence to indicate that vaccination was the cause. These again are very rare. There have been reports from various countries of children who suffered from brain damage after having been vaccinated some time previously, and for which no causal factor could be established. The Pertussis (whooping cough) vaccine in particular has been associated with incidences of brain damage, but a causal link has never been demonstrated. It is worth remembering that there are other causes of brain damage in childhood, and since most children are given vaccines sometime at intervals of two months or less, if brain damage should occur a week or two after a visit to the doctor, it does not mean the vaccine caused brain damage.
The reputation of vaccines have suffered because of these reports of neurological problems which were preceded by vaccination, but because of the rarity of these problems and the very weak link with vaccination, combined with the very real, well proven benefits to individuals and community, even the whooping cough vaccine continues to be widely used.
To answer the question "Are vaccines safe", you must first decide for yourself and your children what you mean by "safe". If you mean are all vaccines absolutely free of any adverse effect, then the answer is definitely no. Vaccines can be regarded as drugs and no drug has been invented which is absolutely safe at any dose and any time. Sometimes you may be quoted a figure, such as "the risk of severe reaction is 1 in 500 000 or less". Numbers are sometimes not easy to relate to real life, in which case try asking yourself such questions as: is it safe to cross the road, to fly in an aeroplane, to ride in cars and buses, to walk on the pavement (sidewalk) in your home town? Vaccines, apart from causing an occasional fever, are safer than all of these things which most of us do everyday. In addition, if you are comparing risks, the serious consequences of diseases like whooping cough and polio, including permanent brain damage, are much more likely to occur from the dieases than from the vaccines which prevent them.
Which vaccines are necessary for children?
Immunisation Schedule. For details see the pages for individual vaccines. A blank indicates that the vaccine is not normally given at that time in that particular country.
| Vaccine |
Thailand |
USA |
UK |
| DTP, Polio |
2 months |
2 months |
2 months |
| 4 months |
4 months |
3 months |
| 6 months |
6 months |
4 months |
| Hib |
|
2,4,6,12-15 months |
2,3,4 months |
| Measles |
9 months |
|
|
| MMR |
15 months |
12-15 months |
12-18 months |
| Hepatitis B |
birth,1,6 months |
birth,1,6+ months |
|
| Jap B Encephalitis |
1 yr (2 doses in 2 weeks) |
|
|
| BCG |
At birth |
|
Infancy or 10+ yrs |
| Booster DTP, Polio |
18 months, 4 yrs |
15 months (no polio), school entry |
4 yrs (DT, Polio) |
The above schedule includes all the most important vaccines. Schedules for other countries around the world are mostly similar to one of the above, with the major exception of Japan, which has a highly unusual vaccination schedule.
Vaccines for Expatriate Families Residing in Thailand
If your family is residing in Thailand, i.e.. your are not a short-term visitor, the basic vaccination requirements for your children are:
- Vaccines they would have had in their home country if they were living there.
- Additional vaccines for protection against diseases found in this region, but not where you came from.
For the latter item, it may not be absolutely essential to have every available vaccine if you are not staying very long. Before you arrived in Thailand you may have already sought advice about vaccines. In my experience the advice can vary from excellent to poor information and occasionally mis-information. You should consult your doctor (local doctor, in Thailand) about the local requirements for vaccines. Most pediatricians in Thailand are aware of the prevalence of diseases and their relative risks, whereas some doctors in other countries may not take care to stay well informed about conditions abroad. It is essential that you have a record of vaccines your children have previously received. It would be useful also if you have the vaccination schedule for your own country as all countries do things differently. If you do not have that information the schedule I propose here should be adequate for most countries except for areas with yellow fever and for Japan.
For vaccination schedules for Thailand, USA and the UK click here.
Hib
The Hib vaccine has for some time now been routinely used for all children under four years of age in Europe, USA, and Australasia. The situation in Thailand is unclear. The Hib bacteria is much rarer in this region than in the West, and the few cases that are found are mainly in overcrowded, poverty stricken areas, therefore for expats, the risks are low while you are in Thailand. Never the less, your children should receive the Hib vaccine if he or she is under four years of age, so that they will be protected for the times you visit your home country.
BCG
This vaccine is probably the most important one to have today. The risk of tuberculosis is on a rapid increase as a corollary of the rise in AIDS. People with AIDS are highly susceptible to TB and unlike other kinds of infections AIDS sufferers get, TB is easy to transmit to healthy contacts. Even in countries like the USA where TB was previously rare and there are no routine vaccination against TB, this prevalence of this disease is multiplying rapidly and it will probably not be long before BCG vaccination become routine in all Western countries. If you will have only one "extra" vaccine, make it the BCG
Hepatitis B
This vaccine has only recently been routinely given in the USA. In many parts of the Far East, hepatitis B is highly endemic, that is to say large numbers of people carry the virus, although only a proportion suffer from any ill effects. The risk of contracting this virus must be regarded as high if your child has any contact with local people such as in international schools. Vaccination against hepatitis B is strongly recommended.
Japanese B encephalitis
This is a rare disease in this region and not seen at all outside of Asia. It is mosquito borne but tends to be seen only in areas where cattle and pigs are reared. It is rarely seen in Bangkok. despite the omnipresent mosquitoes. Vaccination is recommendable as the vaccine is effective and very rarely cause any side effects ( I have never personally seen any).
Hepatitis A
This disease in rarely fatal and almost always self-limiting i.e. you will get better if you contract this virus and do nothing about it, after a week of diarrhoea and possibly jaundice. Young children tend to suffer only mild symptoms and the diagnosis is often missed. The hepatitis A virus is very common in Thailand and therefore vaccination is strongly advised for all unimmune individuals over the age of one year.
Typhoid
Although typhoid is more common in Thailand than in the West, it is still a rare disease, unlike in parts of Africa where it is very common. The problem with typhoid vaccine was that it often caused severe side effects such as localised pain and swelling, and sometimes fever. Newer typhoid vaccines have less side effects but like the old vaccine, they do not give "good" protection. The oral typhoid vaccine is almost useless and the injectable vaccine only gives about 60% protection, useful for Africa but in countries like Thailand where typhoid is rare, there is not a good case for recommending this vaccine. If you feel you are at special risk (for example if you are not much bothered by food hygiene), you can request this vaccine, but you will have to receive boosters every three years and on each subsequent occasion, the risk of side effects increases.
Cholera
This is a useless vaccine. You should refuse it if it is offered to you.
Rabies
Because of the 100% fatality caused by rabies you should always seek help if you are bitten by an animal, even if it is your own pet cat or if your neighbour's dog has a vaccination certificate. Having said this, rabies is not all that common and unless you are a veterinary surgeon or your job involves contact with many animals, it is not really worthwhile to have rabies vaccination, it is expensive, the immunity gained does not last very long, and there may be side effects. The most compelling reason for not having the vaccine however is: if you are bitten by a rabid dog and you seek help without delay, rabies can be prevented. It takes weeks before the rabies virus causes the disease and during those weeks you have enough time to induce active immunity, which can also be supplemented by specific immunoglobulin injection. This will give you immediate passive immunity.
Dengue Fever
Unfortunately there is no vaccine for this common disease but I am mentioning it here because it is so common. It is a viral disease transmitted through mosquitoes. It is especially prevalent during the rainy season and you can certainly catch it in Bangkok and tourist towns. In most people the disease causes severe headaches, high fever, a rash, sometimes diarrhoea and bellyache. The symptoms may last for five to seven days during which all you can do is take painkillers and drink plenty. After this period recovery is usually rapid and complete. For a few unfortunate people, the disease develops into dengue haemorrhagic fever, which has a high mortality especially in children. You should always take precautions against mosquito bites. Use insect repellent lotion every time you plan to be outdoors in the evening. If you do not like to put chemicals on your children's skin, put the lotion on their socks or wristbands.
Malaria
Another mosquito bourne disease which causes great suffering around the world. As yet there is no vaccine for it. I believe in South America someone is progressing well in developing a vaccine. If he succeeds I think he should be given the Nobel prize without a second thought. In the mean time, you should take very careful precautions against malaria if you are planning to travel in to malarial areas in Thailand. You must start the course of medical prophylaxis at least a month before you travel, and always go well armed with mosquito nets, insect repellents, and suitable clothing. These precautions are not necessary however if you are staying in Bangkok or visiting touristy areas like Pattaya or Chiangmai. The species of mosquito that carries the malarial parasite only live in jungle areas and some islands. You are at no risk in Bangkok.
Summary of recommended vaccines
- BCG
Children and Adults - Essential
- Hib
Children Recommended - Adults Not recommended
- Hepatitis B
Children Highly recommended - Adults Special needs only
- Hepatitis A
Children and Adults - Recommended
- Japanese B encephalitis
Children Highly recommended - Adults Special needs only
- Rabies
Children and Adults - Special needs only
- Typhoid
Children and Adults - Special needs only
- Yellow fever
Children and Adults - Not recommended
- Chicken pox
Children and Adults - Not recommended
- Cholera
Children and Adults - Not recommended
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