By Henrylito D. Tacio
Photo courtesy of WHO
“Despite what you may hear or read, all current vaccines are safe,” assures Dr. Zulkifli Ismail, professor of pediatrics and director of Hospital Universiti Kebangsaan Malaysia. “Vaccines have helped prevent more diseases than all antibiotics put together.”
In 2018, the United Nations health agency reported that an estimated 116 million children have vaccinated with three doses of diphtheria-tetanus-pertussis (DTP3) vaccine, protecting them against infectious diseases that cause serious illness and disability or be fatal.
“Vaccines are one of our most important tools for preventing outbreaks and keeping the world safe,” Dr. Tedros Adhanom Ghebreyesus, WHO director-general, said in a press statement.
But like all medicines, side effects can occur after getting a vaccine. “However, these (side effects) are usually very minor and of short duration, such as a sore arm or a mild fever,” the WHO said. “More serious side effects are possible, but extremely rare.”
A person is far more likely to be seriously harmed by disease than by a vaccine. For example, tetanus can cause extreme pain, muscle spasms (lockjaw), and blood clots. Measles can cause encephalitis (an infection of the brain) and blindness. Many vaccine-preventable diseases can even result in death. The benefits of vaccination greatly outweigh the risks, and many more illnesses and deaths would occur without vaccines.
According to WHO, all the ingredients of a vaccine play an important role in ensuring a vaccine is safe and effective. Some of these include antigen (a killed or weakened form of a virus or bacteria, which trains the bodies to recognize and fight the disease that can be encountered later on), adjuvants (help to boost the immune response), preservatives (ensures a vaccine stays effective), and stabilizers (protect the vaccine during storage and transportation).
Vaccines are different from drugs. “A vaccine stimulates your immune system to produce antibodies, exactly like it would if you were exposed to the disease,” explains the US Centers for Disease Control and Prevention (CDC). “After getting vaccinated, you develop immunity to that disease, without having to get the disease first.”
That’s what makes vaccines such powerful medicine. Unlike most medicines, which treat or cure diseases, vaccines prevent them. And this is the reason why children, particularly newly-born babies, are advised to be vaccinated.
“Immunity is the body’s way of preventing disease,” the Atlanta-based CDC says. “When a baby is born, his immune system is not fully developed, which can put him at greater risk for infections. Vaccine reduces a child’s risk of infection by working with his body’s natural defenses to help safely develop immunity to disease.”
Here’s an even more understandable explanation from WHO: “Our immune systems are designed to remember. Once exposed to one or more doses of a vaccine, we typically remain protected against a disease for years, decades or even a lifetime. This is what makes vaccines so effective. Rather than treating a disease after it occurs, vaccines prevent us in the first instance from getting sick.”
Most vaccines are given by injection, but some are given orally (by mouth) or sprayed into the nose. Aside from those mentioned earlier, vaccines protect against many different diseases, including cervical cancer, cholera, hepatitis B, influenza, Japanese encephalitis, measles, mumps, pneumonia, rabies, rotavirus, rubella, typhoid, varicella, and yellow fever.
Vaccines protect people throughout life and at different ages, from birth to childhood, as teenagers, and into old age. “If we delay vaccination, we are at risk of getting seriously sick,” the WHO warned. “If we wait until we think we may be exposed to a serious illness – like during a disease outbreak – there may not be enough time for the vaccine to work and to receive all the recommended doses.”
Not everyone could be vaccinated, though. Among those that cannot be immunized are the very young babies, those who are seriously ill, or have certain allergies. “They depend on others being vaccinated to ensure they are also safe from vaccine-preventable diseases,” the WHO said.
As with all medicines, every vaccine undergoes several studies and testing before being released to the public. “To develop a vaccine, there first has to be research done to understand the nature of the infection you’re trying to prevent,” Prof. Adam Finn, the David Baum professor of pediatrics at the University of Bristol in the United Kingdom, explained to Gary Finnegan’s Vaccine Today. “You need to know enough about the virus or bacterium that causes the infection; you have to understand the structure of the bug because in order to create a vaccine you need to know enough about the infection to be able to mimic it. A vaccine is essentially a mimicked infection.”
Before a vaccine is released for human use, careful steps are taken to ensure that all material is manufactured in an entirely safe and strictly controlled way. “Following pre-clinical research, the vaccine is tested in a very small group of people – sometimes as few as half a dozen – in what is called a Phase I clinical study,” Finnegan wrote. “This helps to rule out major safety problems and also helps doctors to work out the right dose for the next step in the testing process.
“Phase II trials involve giving the vaccine to a larger number of people (often 100 to 200 but sometimes in the 1,000s). At this point, researchers want to see whether the vaccine gives a consistent immune response, and they watch for any side effects that might occur.
“Where a disease is reasonably common, Phase III trials can be conducted to test how the vaccine protects against natural infection. These studies often include tens of thousands of healthy volunteers so that doctors have a better chance of discovering rare problems which did not show up in smaller Phase II studies and prove that the vaccine prevents the disease.”
Meanwhile, there are several new vaccines under development. If approved, these will help prevent more life-threatening diseases – such as Zika, Nipah, or COVID-19 (coronavirus disease 2019) viruses – or improve existing vaccines’ effectiveness.