Vaccines are deemed as one of the greatest scientific innovations in the history of modern medicine as they prevent 2-3 million deaths a year from serious diseases (World Health Organisation, 2021). In the past century, they have helped eradicate smallpox and brought us closer to ending many debilitating, life-threatening afflictions. Due to improved accessibility of vaccines, billions of people today live healthy lives protected from vaccine-preventable diseases like diphteria, measles, pertussis, tetanus, pneumococcal disease and hepatitis.
“Immunisation is a simple and effective way of protecting children from serious diseases that are potentially harmful or even deadly. By immunising a child, you not only protect the individual, but also the broader community by minimising the spread of disease,” says Professor Dr Zabidi Azhar Mohd Hussin, Pro Vice Chancellor, Academic at the International Medical University (IMU) in Kuala Lumpur and Consultant Paediatrician, IMU Healthcare.
Children are invariably exposed to pathogens through their daily interaction with family members, playmates and schoolmates. Therefore, immunisation plays an important role in strengthening their immunity and protection against serious illnesses.
“Newborns naturally inherit their mother’s immunity in the first few months of life. However, this soon wanes. As babies have an under-developed immune system, they may be stricken with various infections four to eight times a year. While young children are generally able to fight off most infections, there may be some pathogens or virulent diseases that are beyond their immune system’s capability.”
Essentially, vaccines work by triggering the immune system to fight against a particular disease. “They contain the same germ that causes a particular disease. But the germs in the vaccine have been killed or weakened so that they do not make your child sick,” explains Professor Zabidi.
Presently, there are four (4) main types of vaccines: Inactivated vaccines are made from a dead virus or bacterium; live-attenuated vaccines use a weakened version of a virus or bacterium; subunit, recombinant, polysaccharide, and conjugate vaccines take a structural component from a virus or bacterium that can train your immune system to attack that part of the germ; and toxoid vaccines derived from the toxins of a germ that makes you immune to its effects.
In addition to these, scientists are working on recombinant vector vaccines which are good for teaching the immune system to fight germs and RNA-based vaccines for longer-lasting immunity.
“When your child gets immunized, his/her body is tricked into thinking that it has been infected with the disease. It starts to manufacture antibodies that kill the germs. These antibodies stay in the body for a long time. So, if the child comes in contact with the disease, his/her immune system is able to respond more effectively, preventing the disease from developing or greatly reducing its severity,” he adds.
Prof Zabidi highlights in particular in his contributing chapter on “Vaccines and Children”, due to be published by The Universiti Sains Malaysia, USM. Measles can cause death due to inflammation in the lungs and other vital organs; whilst Diphtheria incapacitates the nervous system and affects the heart with a death rate of up to 50%. Poliomyelitis, caused by Enterovirus C, is spread by faecal-oral transmission (taking food or water contaminated by stool of an infected person) and also by saliva droplets, that may result in muscle weakness and paralysis. Mycobacterium Tuberculosis which causes Tuberculosis (TB) is ever-present in the air and community and causes serious complications and damage to the lungs and other vital organs. Mumps caused by the Paramyxovirus may cause encephalitis and deafness; while Pneumococcal infections, caused by the bacterium Streptococcus pneumoniae, can lead to pneumonia, septicaemia (blood poisoning), meningitis and possibly death.
“The National Immunisation Programme (NIP), introduced by the Ministry of Health of Malaysia (MOH) since the 1950s to curb the spread of infectious diseases in the community currently administers free vaccinations to children that protect against 13 potentially harmful diseases,” says Professor Zabidi.
“They are Bacillus Calmette-Guerin (BCG), a vaccine that gives protection against tuberculosis; 6-in-1 vaccine which contains: diphtheria(D), tetanus(T), polio, pertussis, Hepatitis B and Haemophilus Influenza type B; MMR, the combination of Measles(M), Mumps(M) and Rubella(R), and HPV (Human Papillomavirus), a vaccine that protects against cervical cancer. For Sarawak only, there is an additional vaccine that fights against Japanese Encephalitis, JE.”
“Children receive these vaccines within the first 18 months of their lives, except for the HPV vaccine which is given to teenage girls at 13 years of age.” Professor Zabidi says that since the NIP was introduced, cases of serious infectious diseases have decreased significantly; Malaysia was declared free from polio in the year 2000.
However, there are lingering traces of measles, mumps and rubella detected in some pockets of society primarily in rural areas even in this present day as immunisation is not compulsory by law in Malaysia. “It is estimated that only 92% of Malaysians have immunity against rubella and we have not been able to eradicate mumps completely,” says Professor Zabidi. “There is still some work to be done in Malaysia in terms of public health awareness and education where immunisation is concerned.”
IMU Pro Vice Chancellor, Academic with a special interest in Paediatric Neurology and Medical Education