With all the mis- and disinformation about vaccines going around, it is a good time to remind ourselves of two important facts.
Firstly, vaccines prevent disease, not infection.
However, and secondly, if herd immunity is achieved through sufficient vaccination coverage, it will significantly decrease the risk of infection within the community.
“People always think that when you vaccinate, you eliminate the disease.
“But that’s not always the case,” says Pfizer Biopharma Emerging Markets Medical Affairs Respiratory Vaccines lead Dr Mark Fletcher.
In the more than two centuries since British physician Dr Edward Jenner came up with the first vaccine, only smallpox has been successfully eradicated from our world, and this was via herd immunity.
Defined as the resistance to the spread of a contagious disease in a community (the herd) due to high levels of immunity to the disease, whether from vaccination or previous infection, herd immunity is only effective when sufficient members of the community are immunised against the relevant bacteria or virus.
For most vaccine-preventable diseases, the aim of the vaccine is to prevent the recipient from developing a severe or deadly form of the disease.
“So that’s what vaccines do: they just put the balance of nature on the side of the host,” says Dr Fletcher.
“We’re not there to drive out every infectious disease of mankind; we’re just there to sort of readjust the rules of the game so that human beings are a little bit stronger in case the infection comes.”
Vaccines act as a trigger to activate the immune system’s defences against the targeted virus or bacteria.
Once activated, our immune system retains a memory of these defences and can quickly reactivate them if the actual virus or bacteria infects our body.
The virus or bacteria can then be destroyed before it spreads too much inside us and causes severe disease.
Template for vaccines
Speaking to South-East Asian media during the Pfizer Vaccines Educational Media Session held in Brussels, Belgium late October (2023), Dr Fletcher notes that there are six types of vaccine technology platforms.
Pfizer, an American multinational pharmaceutical and biotechnology corporation, specialises in two: the messenger ribonucleic acid (mRNA) platform and the subunit platform, with a further subspecialisation in conjugate vaccines.
The other four types of vaccine technology platforms are live-attenuated vaccines (e.g. measles, mumps and rubella, or MMR, and chickenpox vaccines), inactivated vaccines (e.g. polio and influenza vaccines), toxoid vaccines (e.g. tetanus and diphtheria vaccines) and viral vector vaccines (e.g. Ebola and the AstraZeneca Covid-19 vaccines).
The partnership between Pfizer and German biotechnology company BioNTech is, of course, well-known for producing one of two mRNA Covid-19 vaccines that were widely used around the world during the pandemic (the other was from American pharmaceutical and biotechnology company Moderna).
Although it took around half a century from the time mRNA was discovered in the 1960s to the first phase 1 clinical trial of an mRNA vaccine in humans in 2015, the platform can now act as a template into which genetic information about a virus can be loaded onto and turned into a vaccine.
The key challenge, Pfizer Emerging Markets Covid-19 senior medical director Dr Julia Spinardi said during her presentation, is to identify the appropriate antigen (or part of the virus) for our immune system to target for the best effectiveness, and unravelling its genetic code.
In the case of the SARS-CoV-2 virus, this turned out to be the virus’ spike protein.Therefore, only the genetic information necessary for the body’s cells to reproduce the virus’ spike protein is encoded in the Covid-19 vaccine.
The pandemic, of course, served as the baptism of fire for this platform, demonstrating its ability to be precise, effective and faster than the other types of vaccine platforms.
According to Dr Spinardi, it would only take about 100 days to produce the vaccine for any virus, once the appropriate antigen and its genetic code is identified.
This is helped by the fact that the production process requires far less biological components, like cellular cultures, and the accompanying equipment and labs necessary to support these components, compared to other vaccine platforms.
“It facilitates your production and laboratory facilities because you don’t need a bank of cells any more.
“You can synthesise mRNA more easily and in facilities that are more adaptable,” she says.
In addition, the flexibility of the platform means that vaccines targeting more than one virus can be easily produced.
“One of the benefits of mRNA is that you can include as many ‘recipes’ as you want in the vaccine,” she says – a “recipe” referring to an antigen’s mRNA code.
The main target for Pfizer at the moment is a combination influenza (flu) and Covid-19 mRNA vaccine, which would make it more convenient for people to get protection against both infectious diseases in one shot.
Other mRNA vaccines in the works by the pharmaceutical corporation are a flu vaccine, various modified Covid-19 vaccines for children, and a shingles (varicella) vaccine.
Two-for-one shot
Another area of vaccine development that holds much potential is maternal immunisation.
In a 2022 article, Bill & Melinda Gates Foundation Pneumonia deputy director Dr Padmini Srikantiah wrote: “There is one life-saving solution that the world has yet to fully unleash: maternal immunisation.”
Babies up to six months of age are vulnerable to infections because their immune systems are not yet fully developed.
Because of this, they have to rely on antibodies from their mother for protection.
These antibodies are passed on to them while in the womb, as well as through breast milk.
Dr Padmini continued: “Vaccinating women during pregnancy can not only protect them from disease, but can also enable them to pass protective antibodies to their babies in a process known as passive immunity.
“These maternal antibodies offer newborns critical protection in the vulnerable first days and months of life.”
Pregnant women have long been recommended to get vaccinated against pertussis (whooping cough) in the form of the Tdap (tetanus, diphtheria and pertussis) vaccine, and the flu.
In fact, Health Minister Dr Zaliha Mustafa announced in August (2023) that all pregnant women, including non-citizens, can get the Tdap vaccine for free at government primary healthcare facilities nationwide starting next year.
August (2023) was also when the US Food and Drug Administration (FDA) approved the first – and currently, only – maternal respiratory syncytial virus (RSV) vaccine, which is produced by Pfizer.
ALSO READ: Vaccinate mum to protect baby against RSV
Dr Fletcher explains: “RSV is well known for causing serious disease in young children, especially newborns, as well as in people who are frail and elderly.
“There’s no treatment and it is associated with mortality (death).”
This is why it was a natural target for vaccine development, he adds.
Pfizer is also working on a maternal vaccine for invasive Group B Streptococcus pneumonia bacteria.
Dr Fletcher notes that the invasive forms of pneumococcal disease, while rare, cause the most severe disease and can often be fatal.
Aside from pneumonia, the infection can also cause meningitis (infection of the brain’s lining) and sepsis (where the entire body has a severe reaction to an infection), as well as lifelong consequences like hearing loss, problems with brain function and movement, and seizures.
ALSO READ: Protect against pneumococcal infections
One important part of maternal immunisation is the timing.
Says consultant infectious diseases physician Dr Leong Hoe Nam: “The ‘gates’ to release the antibodies from the mother to the child opens at about 32 weeks of gestation [pregnancy].
“So we try to push all the antibodies in at least two weeks before then, so you load up and you have the maximum antibodies to share across.”
And the bonus is that mums also get protected against those diseases.
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