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Vaccine Safety: Your Questions Answered

Medically reviewed by Carmen Fookes, BPharm. Last updated on Aug 16, 2022.

1. Is Vaccination Effective?

The short answer to this is YES! Vaccination has successfully eradicated diseases such as smallpox which killed over 300 million people in the early twentieth century alone. Vaccination has also been successful in reducing world-wide infection rates of diseases such as polio, diphtheria, mumps, rubella, haemophilus influenzae type b (Hib), chickenpox, human papilloma virus (HPV) and measles. Only clean water and improved sanitation have made more of a difference to global disease rates.

However, many of these diseases are still prevalent around the world. Occasionally, outbreaks will occur and the viruses and bacteria that cause these illnesses can be easily transferred from person-to-person. No vaccine is 100% effective, so even vaccinated people may still contract a particular disease during an outbreak, albeit in a much milder form. For example, measles vaccination has 97% efficacy after 2 doses (meaning 3 out of 100 vaccinated children will still get measles if exposed to it). Compare that to your chances of contracting a disease if you are not vaccinated...which could be up to 100%.

How long protection lasts for varies with the different vaccines. Recent studies suggests the whooping cough (pertussis) vaccine lasts only for a few years. Check with your doctor to see how frequently you need to get revaccinated.

2. What Are The Most Likely Side Effects From Vaccines?

Because most vaccines are given by injection and pierce the skin, redness around the site of the injection and a sore arm are common. Some people may also get a short-lived, low-grade fever, headache, or feel tired for a day or two after certain vaccines.

Occasionally, people may be allergic to a specific component in a vaccine (for example, eggs are used in the process of making some vaccines). If you are prone to allergies, tell your doctor or pharmacist and they will check what ingredients make up the vaccine. Serious reactions have been documented to some vaccines, but the prevalence is so rare (less than 1 per million doses), that it is hard to tell whether they were caused by the vaccine or not.

3. Why Do Breastfed Babies Need Shots?

Many people assume that breastfeeding protects against disease, which is true, but only for the diseases that the mother is actually immune to. And this protection is short-lived, lasting only three to six months. Breastfeeding hardly ever protects against diseases like pertussis (whooping cough), which is common and can be deadly in newborns. Similarly, few measles antibodies pass from a mother to her breastfed child. Children can die from measles if it spreads to the brain.

Make sure your newborn receives their scheduled shots, whether they are breastfed or not.

4. Are All Ingredients Used In Vaccines Safe?

Some vaccines contain ingredients to boost their effectiveness or are left over from the manufacturing process.

Aluminum salts are commonly added to enhance the immune response. However, the amount present is tiny - far less than that found naturally in breast milk or infant formula.

Antibiotics may also be used to prevent bacterial contamination. Formaldehyde inactivates viruses and small residual amounts can be found in some vaccines.

All additional ingredients used in vaccines have been thoroughly examined by the FDA and found to be safe in the quantities used.

5. Weren't Some Vaccines Linked To Autism?

In 1998, The Lancet published a research paper submitted by Andrew Wakefield claiming that colitis and autism spectrum disorders (ASD) were linked to the combined measles, mumps, and rubella (MMR) vaccine. The media had a field day, but it took extensive investigations by Sunday Times journalist, Brian Deer, to uncover the truth. Wakefield had manipulated evidence in order to profit from new tests he aimed to launch on the back of an MMR vaccination scare. In addition, he had also conducted unnecessary colonoscopies and lumbar punctures on susceptible children with autism without ethics committee consent. Wakefield was found guilty of serious professional misconduct in May 2010 and struck off the Medical Register.

In the aftermath of the MMR vaccine controversy, vaccination rates dramatically declined in the United States, United Kingdom and Ireland, leading to a corresponding increase in the number of cases of measles and mumps. Despite multiple, large, epidemiological studies being undertaken since the initial 1998 claims, none of which found a link between MMR and autism, his fraudulent study contributed to a climate of distrust of all vaccines, and his work is still quoted by anti-vaccination groups today.

Thimerosal was also investigated as having a possible link to autism; however, at least nine studies have found no link between thimerosal-containing vaccines and ASD, as well as no link between MMR and ASD. Autism rates have continued to trend upwards even since thimerosal was removed from vaccines in 2001.

6. Isn't It Better for My Child to Build-Up Natural Immunity?

Some people believe exposing their child to certain illnesses, such as the chickenpox, is a better way to boost immunity than vaccination. However, people forget how awful and deadly some of these illnesses can be.

Chickenpox can be excruciatingly uncomfortable and can cause pneumonia in some children. Children have died from measles in the past or been left blind or deaf. Mumps can make pre-adolescent boys sterile and prior to widespread vaccination, Hib was the leading cause of death in children under 5 years.

Weigh it up. Sore arm and slight fever from vaccination versus a risk to your child's life. Which do you choose?

7. I Was Never Vaccinated As A Child But Now Want To Travel. What Shall I Do?

If you have never been vaccinated, then you will need to get several different types of vaccinations before you travel. Take the quiz on the CDC website to see exactly which ones you will need.

Many countries have lower vaccination rates than the United States which means that several vaccine-preventable diseases are common. If you went overseas without any vaccinations you would be at high risk of catching them.

8. Why Do I Need To Have The Flu Vaccine EVERY Year?

Since 2010, the Centers for Disease Control and Prevention (CDC) have recommended a yearly flu vaccine for EVERYONE aged over 6 months.

Influenza viruses are constantly changing. Each year, experts from around the world analyze trends and determine which viruses are most likely to cause illness in the coming season. The viruses protected against in the previous years vaccine may not always be the same as those protected against for the coming season, and that is why yearly vaccination is recommended. In addition, the protection offered by vaccination wanes with time.

Finished: Vaccine Safety: Your Questions Answered

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