There’s a lot of misinformation circulating about vaccines, especially online, and it can be hard for parents to separate fact from fiction.

From fears about harmful ingredients to concerns about autism, these myths can create unnecessary anxiety. In reality, vaccines are rigorously tested, safe, and one of the most effective ways to protect children from serious diseases.

Here’s what every parent should know.

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DISCLAIMER:

While I am a practising doctor, the information on this site is for educational purposes only. It does not take into account your personal circumstances, which can significantly affect medical decision-making and treatment. This content therefore does not constitute medical advice, and should not be relied upon for diagnosis or treatment. Always consult a qualified healthcare provider regarding any health concerns.

This article was written on the 01/12/2025 using up-to-date sources at that time. Please be aware that medical information and guidelines change often.

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1) Vaccines Contain Harmful Ingredients, Like Mercury

The key ingredient in all vaccines is the active ingredient (the part that teaches the immune system how to recognise the germ). Beyond that, the main ingredient is water.

Some ingredients listed on the information leaflet may have been used during the manufacturing process but don’t remain in the final vaccine, or remain only in trace amounts. There is no evidence to suggest that these tiny quantities could cause harm.

Many vaccine ingredients may sound unfamiliar, but that doesn’t mean they’re dangerous. For example:

• Formaldehyde sounds worrying and can be harmful in high levels, but the amount in vaccines (if present at all) is less than what is naturally found in your own bloodstream. It may be used very early in the vaccine manufacturing process to kill or inactivate pathogens, but is diluted out after – if it remains in the vaccine, it’s only in trace amounts.

2) Natural Immunity Is Better Than Immunity Through Vaccinations

While catching a disease often does give long-lasting immunity, it can come at a dangerous cost. Natural infection with measles, meningitis, or whooping cough can cause hospitalisation, disability, and even death.

Vaccines give your child strong immunity without exposing them to the risks of the actual disease. They are the safer way to build protection.

3) Multiple Vaccines At Once Can Overload the Immune System

A child’s immune system encounters thousands of new pathogens every day just from breathing, touching surfaces, and feeding. The pathogens they are exposed to through vaccines are a tiny fraction of what they are exposed to daily.

Several studies have shown that giving multiple vaccines at once is safe, and when a new vaccine becomes available, it has already been tested alongside other vaccinations that are due in that age-group. If there were any concerns, it wouldn’t be put out to the public.

4) Vaccines Cause Sudden Infant Death Syndrome (SIDS)

SIDS is where there is a death of a baby (less than 1-year-old), where no cause has been found. SIDS is most common in babies 2-4 months old, which falls at the same time as children starting to have vaccinations. So naturally, people have questioned whether there is a link between the two.

However, just because two things can appear to happen at the same time, does not mean that they are related. And in fact, this has been studied over many years – there is currently no evidence to suggest that vaccines are linked to SIDS.

5) Vaccines Cause Autism

In 1998, a study was published in The Lancet by British Gastroenterologist Dr Andrew Wakefield and 12 others, that suggested a link between the MMR vaccine, enterocolitis (inflammation of the bowels) and autism.

Even though this study, which only looked at 12 children, has since been retracted and discredited, the sharp drop in children having the MMR vaccine persisted for years.

Evidence has since shown there is no known link between vaccines and autism. In fact, there have been over 40 high-quality studies, involving over 5.6 million people, that have found no connection. And unfortunately for Dr Wakefield, he was struck off the GMC register for making this claim.

6) My Child Doesn’t Need Vaccinating Because All The Kids Around Them Are Immune

This belief undermines herd immunity – the community protection that keeps vulnerable people safe.

If too many people skip vaccines, infections spread, and outbreaks occur (as seen with recent measles outbreaks across the UK and Europe).

This then increases the risk to those who are unable to have vaccines for medical reasons, those who are immunosuppressed (have a lowered immune system), pregnant women, newborn babies, and those who are undergoing active cancer treatment.

7) Why Do We Need To Vaccinate Children If These Diseases Aren’t Around Anymore?

Because they aren’t around anymore thanks to vaccines.
But they have not disappeared, and may still be prevalent in other areas of the world, take Diphtheria for example – this is still present in areas such as Africa, South America, and South East Asia.

If we stop vaccinating children, these illnesses can resurge again. Take the recent resurgence of Measles in the UK and Europe – in 2017, the World Health Organisation gave the UK the “measles elimination status” – but this has since been lost in recent years.

8) Vaccines Weaken My Child’s Immune System

Vaccines do the opposite: they train the immune system.
They help it learn to recognise dangerous germs and respond faster and more effectively.

Research consistently shows that vaccinated children have no reduction in immune function.

9) Vaccines Can Give Children The Disease

Routine UK childhood vaccines do not cause their diseases.

• Inactivated vaccines cannot cause infection.
• Subunit and mRNA vaccines contain no live virus.
• Live-attenuated vaccines (like MMR) contain weakened forms that cannot cause disease in healthy children. Live viruses aren’t given to children who have a lowered immune system, as they are more likely to become unwell.

Some children may get mild, short-lived symptoms such as a fever or small rash – a normal immune response, not the disease itself.

10) HPV Vaccine Causes Infertility

There is no evidence that the HPV vaccine affects fertility in boys or girls, from several large studies.

HPV vaccination actually protects future fertility by reducing risk of cervical cancer and reducing the need for invasive treatments.

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Vaccines are a cornerstone of public health, protecting children and communities from potentially life-threatening illnesses. Understanding the facts can help parents make informed decisions and feel confident in keeping their children safe.

If you do have any concerns, please book in to see your clinician – they will be happy to discuss any concerns you may have further.

For more, read our article “Childhood Vaccines: The Ultimate Guide For Parents“, where we look at everything from why we vaccinate when we do, the role of herd immunity in protecting our kids, to possible side effects and the vaccination schedule.