Beyond the jab: The science and systems behind vaccination

KUALA LUMPUR: FOR many people, a vaccine is simply a jab to prevent a disease.

But behind that injection is a complex system of science, surveillance, regulation, manufacturing and public confidence that determines how vaccines are developed, assessed, selected and delivered.

University Malaya Medical Centre (UMMC) family medicine specialist Dr Megat Mohamad Amirul Amzar Megat Hashim said it was important to understand that vaccination and natural infection expose the immune system to an infectious threat in very different ways.

With natural infection, the body has to encounter and fight the actual pathogen, with the outcome ranging from mild illness to serious complications. Vaccination, on the other hand, prepares the immune system to recognise specific components of a pathogen without requiring a person to first experience the disease.

"This distinction is particularly important for pneumococcal disease, caused by Streptococcus pneumoniae, a bacterium that can colonise the nose and throat without causing symptoms but can sometimes progress to serious infections such as pneumonia, bacteraemia, sepsis and meningitis," he said.

Vaccination gives the immune system a head start, allowing it to respond more effectively if it later encounters the pathogen.

But determining which vaccine is appropriate is not simply a matter of choosing the product with the highest number of serotypes.

Higher-valency pneumococcal vaccines cover more serotypes and may offer broader coverage. However, the more important question is whether those additional serotypes correspond to the disease burden and epidemiology of the population being protected.

That makes continuous disease surveillance an essential part of vaccine policy.

COUNTING DISEASE, NOT JUST SEROTYPES

Dr Amirul said systematic, nationwide surveillance was needed to establish which pneumococcal serotypes were circulating, which were linked with invasive disease and how those patterns changed over time, particularly after the introduction of vaccination programmes.

Historical pre-vaccination studies provide an important baseline, but they cannot fully describe the current disease landscape.

More recent carriage studies can provide additional information on circulating strains, although the presence of pneumococcal bacteria in the upper respiratory tract should not be treated as a direct measure of invasive disease.

"Such surveillance should involve multiple stakeholders, including healthcare institutions, academia and government, with industry potentially contributing expertise and resources," he said.

The data should cover invasive pneumococcal disease, circulating serotypes, vaccination status, breakthrough infections, antimicrobial resistance and vaccine coverage.

"We should not choose a pneumococcal vaccine simply by counting serotypes. We should count disease," he said.

"Global evidence tells us what a vaccine can do. Malaysian surveillance tells us what Malaysia actually needs."

The principle extends beyond pneumococcal vaccination. Vaccine policy needs to bring together international clinical evidence and safety data with local epidemiology, public-health priorities and regulatory requirements.

VACCINATION ACROSS THE LIFE COURSE

Vaccine decisions also extend beyond childhood.

Dr Amirul said vaccination should be viewed as a life-course approach, with recommendations tailored to age, health status and individual risk.

This can include annual influenza vaccination and pneumococcal vaccination for older adults and people with chronic conditions, as well as other vaccines recommended according to a person's circumstances and exposure risks.

The underlying principle is that vaccination needs to be matched to the individual's risk, as well as the disease burden within the wider population.

BUILDING PUBLIC CONFIDENCE

Scientific evidence alone does not determine whether a vaccination programme is successful. People must also have confidence in the vaccines being offered.

Vaccine hesitancy does not necessarily mean a widespread rejection of immunisation. Concerns can arise when people encounter newer vaccines, unfamiliar information, misinformation or questions about safety and effectiveness.

Vaccines work by safely stimulating the immune system to build protection without exposing people to the risks associated with natural infection.

Dr Amirul said clear, evidence-based communication from healthcare professionals, regulators, government and industry was therefore important in helping the public understand the benefits and limitations of different vaccines.

"Clear communication is essential. Parents and the public need to understand what a vaccine protects against, its benefits and limitations, how safety is monitored and why recommendations may evolve," he said.

When recommendations change, explaining the evidence behind those decisions can help people understand the reasoning rather than simply being presented with the outcome, he added.

REGULATION AND SAFETY

Regulation provides another layer of protection.

Before a vaccine is used, regulatory authorities assess evidence relating to its quality, safety and efficacy or effectiveness. Monitoring continues after introduction to identify potential safety signals and assess how the vaccine performs in wider populations.

Vaccine safety is therefore not a one-off assessment completed before a product reaches the market. It is an ongoing process involving surveillance, investigation and communication.

Vaccine decisions must consider the benefits and potential risks in the context of the disease being prevented and the available scientific evidence.

This also means vaccine confidence should be built around evidence, safety monitoring and regulatory oversight rather than assumptions about where a vaccine is developed or manufactured.

STRENGTHENING SUPPLY RESILIENCE

A strong immunisation programme also depends on reliable access to vaccines.

That brings domestic research, manufacturing capability, technology transfer, skilled workers and supply chains into the wider vaccine conversation.

For Malaysia, strengthening domestic capabilities could improve resilience during global supply disruptions while building expertise that supports the pharmaceutical sector.

However, resilience does not necessarily mean every vaccine must be manufactured locally. A robust system can also involve diversified suppliers, technology partnerships, scientific expertise, strong regulatory capacity and reliable supply chains.

Greater capability in vaccine development and manufacturing could also create opportunities to serve regional and export markets.

Dr Amirul said that including halal-certified pharmaceutical products within this ecosystem could open additional market opportunities for Malaysia.

BEYOND THE VIAL

For pneumococcal vaccines, as with other vaccines, the issue therefore extends beyond choosing between products.

It is about matching vaccine policy to disease patterns, monitoring how those patterns change, assessing safety and effectiveness, maintaining public confidence and ensuring reliable access over the long term.

"Introducing the vaccine is not the end of the story. It is the beginning of the next chapter of surveillance," said Dr Amirul.

Ultimately, vaccination is not simply about what is in the vial.

It is about the science behind it, the disease it is intended to prevent, the evidence used to guide its use and the systems needed to sustain protection across the population.

The data should cover invasive pneumococcal disease, circulating serotypes, vaccination status, breakthrough infections, antimicrobial resistance and vaccine coverage.

"We should not choose a pneumococcal vaccine simply by counting serotypes. We should count disease," he said.

"Global evidence tells us what a vaccine can do. Malaysian surveillance tells us what Malaysia actually needs."

The principle extends beyond pneumococcal vaccination. Vaccine policy needs to bring together international clinical evidence and safety data with local epidemiology, public-health priorities and regulatory requirements.

VACCINATION ACROSS THE LIFE COURSE

Vaccine decisions also extend beyond childhood.

Dr Amirul said vaccination should be viewed as a life-course approach, with recommendations tailored to age, health status and individual risk.

This can include annual influenza vaccination and pneumococcal vaccination for older adults and people with chronic conditions, as well as other vaccines recommended according to a person's circumstances and exposure risks.

The underlying principle is that vaccination needs to be matched to the individual's risk as well as the disease burden within the wider population.

BUILDING PUBLIC CONFIDENCE

Scientific evidence alone does not determine whether a vaccination programme is successful. People must also have confidence in the vaccines being offered.

Vaccine hesitancy does not necessarily mean a widespread rejection of immunisation. Concerns can arise when people encounter newer vaccines, unfamiliar information, misinformation or questions about safety and effectiveness.

Vaccines work by safely stimulating the immune system to build protection without exposing people to the risks associated with natural infection.

Dr Amirul said clear, evidence-based communication from healthcare professionals, regulators, government and industry was therefore important in helping the public understand the benefits and limitations of different vaccines.

"Clear communication is essential. Parents and the public need to understand what a vaccine protects against, its benefits and limitations, how safety is monitored and why recommendations may evolve," he said.

When recommendations change, explaining the evidence behind those decisions can help people understand the reasoning rather than simply being presented with the outcome, he added.

REGULATION AND SAFETY

Regulation provides another layer of protection.

Before a vaccine is used, regulatory authorities assess evidence relating to its quality, safety and efficacy or effectiveness. Monitoring continues after introduction to identify potential safety signals and assess how the vaccine performs in wider populations.

Vaccine safety is therefore not a one-off assessment completed before a product reaches the market. It is an ongoing process involving surveillance, investigation and communication.

Vaccine decisions must consider both the benefits and potential risks in the context of the disease being prevented and the available scientific evidence.

This also means vaccine confidence should be built around evidence, safety monitoring and regulatory oversight rather than assumptions about where a vaccine is developed or manufactured.

STRENGTHENING SUPPLY RESILIENCE

A strong immunisation programme also depends on reliable access to vaccines.

That brings local research, manufacturing capability, technology transfer, skilled workers and supply chains into the wider vaccine conversation.

For Malaysia, strengthening domestic capabilities could improve resilience during global supply disruptions while building expertise that supports the country's pharmaceutical sector.

However, resilience does not necessarily mean every vaccine must be manufactured locally. A robust system can also involve diversified suppliers, technology partnerships, scientific expertise, strong regulatory capacity and reliable supply chains.

Greater capability in vaccine development and manufacturing could also create opportunities to serve regional and export markets.

Dr Amirul said that including halal-certified pharmaceutical products within this ecosystem could potentially open additional market opportunities for Malaysia.

BEYOND THE VIAL

For pneumococcal vaccines, as with other vaccines, the issue therefore extends beyond choosing between products.

It is about matching vaccine policy to disease patterns, monitoring how those patterns change, assessing safety and effectiveness, maintaining public confidence and ensuring reliable access over the long term.

"Introducing the vaccine is not the end of the story. It is the beginning of the next chapter of surveillance," said Dr Amirul.

Ultimately, vaccination is not simply about what is in the vial.

It is about the science behind it, the disease it is intended to prevent, the evidence used to guide its use and the systems needed to sustain protection across the population.