Vexed by vaccines

Vaccines have been one of the biggest success stories of modern medicine. The World Health Organization has estimated that at least 10 million deaths were prevented between 2010 and 2015 thanks to vaccinations. Many million more lives were protected from diseases such as pneumonia, diarrhoea, whooping cough, measles and polio.

The fact that vaccines are administered to healthy people to prevent diseases which have become rare, largely thanks to immunisation, has raised concerns about vaccine safety. As the devastating effects of the diseases are no longer so prominent, people have started focusing on the side effects of vaccination.

In some instances, concerns about the safety of certain vaccines have led to downturns in vaccination rates and outbreaks of disease. Unfounded allegations regarding the adverse effects of vaccines typically target feared diseases, or syndromes such as autism, sudden infant death syndrome (SIDS) and multiple sclerosis.

Beliefs about vaccination

People may come across confusing messages that can leave them feeling ambivalent about vaccination. Among parents, only a small minority refuse vaccines for their children. Their rejection of vaccination may be due to a wider scepticism about orthodox medical interventions and support for alternative approaches to health.

Some people have religious or philosophical objections. Some see mandatory vaccination as an interference by the government into what they believe should be a personal choice. Healthcare workers administering vaccines should try to understand a patient’s concerns, fears, and beliefs, and take them into consideration while offering vaccines.

Myths & concerns: Concerns about the manufacturing and testing of vaccines are raised because of the possibility that they may contain toxic or harmful substances used in the manufacturing process. Here are some concerns and the facts about the same:

Vaccines are unsafe

The facts: In general, no pharmacological agent can be considered 100% safe. However, all vaccines currently available in the world must pass stringent safety testing before being approved for use. The majority of problems thought to be related to the administration of a vaccine are actually not due to the vaccine itself. Many are coincidental events that just happen to occur at the same time as the vaccination. This is particularly the case in the first year of a child’s life, when vaccines are given regularly.

Vaccines may produce some undesirable side effects, such as pain and redness at the injection site or fever, but most reactions are mild and resolve quickly.

Vaccines are not adequately tested

The facts: Before vaccines are made available for use, they are rigorously tested on thousands of people in progressively larger clinical trials, which are strictly monitored.

After the introduction of a vaccine into general use, there is an ongoing review of the vaccine’s efficacy and safety through a variety of mechanisms, such as further clinical trials and surveillance of disease and a vaccine’s adverse events.

Vaccines contain foreign proteins

The facts: Depending on their purpose and specific composition, vaccines can contain live viruses, killed viruses, purified viral proteins, inactivated bacterial toxins or bacterial polysaccharides. Vaccines are complex pharmaceutical products, which need to withstand transport, storage and environmental changes. To ensure they are stable over time, vaccines can contain additives, such as gelatin or albumin. Furthermore, some vaccines contain tiny residual quantities of substances used during the manufacturing process, such as formaldehyde, antibiotics, egg proteins or yeast proteins.

Vaccines are contaminated with foreign viruses
The facts: While bacterial vaccines are not grown in cells, viruses cannot survive outside of cells. Therefore, viral vaccines require cells in which the attenuated (weakened) vaccine viruses can be grown.

Vaccines contain toxic additives

The facts: Preservatives are required when vaccines are produced in multi-dose vials for mass vaccination, usually as an emergency measure, for example, during a pandemic. In the past, a preservative occasionally used was thiomersal (or thimerosal), a mercury-based product. Thiomersal contains ethyl mercury, which has not been associated with any of the toxic effects linked to the related compound, methyl mercury, a known neurotoxin. Thiomersal has been used in small amounts in vaccines for about 80 years with no evidence of it being harmful.

Vaccines weaken the immune system

The facts: Healthy people have the capacity to mount responses to every infection they could possibly encounter. Vaccines do not weaken the immune system, but strengthen it by stimulating defence mechanisms that provide protection against specific diseases.

Vaccines cause or spread the diseases they are supposed to prevent

The facts: An exception to this are live attenuated viral vaccines, which contain weakened (‘attenuated’) forms of the virus that the vaccine aims to protect against. The weakened virus does replicate in the host to create an immune response, but cannot cause the disease, except on rare occasions.

Vaccines can cause cancer

The facts: Two vaccines, hepatitis-B vaccine and human papillomavirus (HPV) vaccine, actually act to prevent cancer. The hepatitis-B vaccine prevents liver cancer.

(The author is the chief of pediatric infectious diseases at Manipal Hospitals.)