What are the facts about vaccines?

Vaccinations are one of the best ways to protect yourself and your children against many serious diseases. Here you will find factual information to help clear up confusion caused by some myths about them. You can then make a more informed choice for yourself and your whānau.

On this page, you can find the following information:

Are vaccines safe?

Fact: Vaccines are very safe. Most vaccine reactions are temporary and minor, such as a fever or sore arm. It is rare to have a serious reaction (often called a serious health event) following a vaccination. You are far more likely to be seriously injured by a vaccine-preventable disease than  by a vaccine. The benefits of vaccination greatly outweigh the risk, and without vaccines many more disabilities and deaths would occur. 

Can you get the disease from having the vaccination?

Fact: You cannot get the disease from the vaccine. Vaccines stimulate your immune system to produce an immune response similar to a natural infection, but they don’t cause the disease or put you at risk of its potential complications. Most vaccines only contain a fragment of the germ so it isn’t possible to contract the disease from the vaccine. A few vaccines contain live organisms, and when vaccinated some people may develop a rash, but only with a few spots, and a fever. This isn’t harmful, and can actually show that the vaccine is working.

Do vaccines have harmful ingredients in them?

Fact: Vaccines do not contain harmful levels of ingredients. Vaccines contain ingredients that allow them to be safely given to you. Any substance can be harmful in significantly high doses, even water. The ingredients in vaccines are at a lower level than what we are naturally exposed to in our environment. This means they do not cause harm as part of a vaccine.

Is natural immunity better than immunity through vaccination?

Fact: Natural immunity occurs when you have to fight off an infection. If you survive the infection, you become immune to the germ that caused it. 
It is true that natural immunity may sometimes (but not always) be stronger than vaccine-acquired immunity, but the risks of this approach far outweigh its benefits. Some vaccines actually provide better immunity than natural infection. 

For example, to develop natural immunity to measles, a child would need to catch measles first. However, measles can cause many uncomfortable symptoms and can lead to complications, including death. About 1 in 20 children develop pneumonia, and a quarter of people need a stay in the hospital. Measles complications can be life threatening. The World Health Organization (WHO) states that between 2000–2017, vaccinations contributed to an 80% decrease in measles-related deaths. 

Developing vaccination-acquired immunity to measles involves a far lower risk of harm and it likely lasts a lifetime. It is extremely rare that someone reacts severely to the vaccine. 

Vaccination is a safer choice than naturally acquired immunity and can save a child from having to go through a serious illness.

Do we need vaccines now that disease rates are low?

Fact: Vaccine-preventable disease rates have dropped because vaccination is now a widespread and common practice. In recent years, however, the number of people contracting some vaccine-preventable diseases has increased. Research has found that children who do not get vaccinated are a contributing factor to this troubling trend. 

To prevent the spread (and return) of several diseases, it is vital that children continue to receive vaccinations.

Do vaccines weaken a child's immune system?

Fact: Vaccination actually strengthens your immune system. Vaccination prompts your body to produce cells and antibodies to fight off the infection, teaching the immune system how to fight off the disease. This strengthens your immune system’s ability to fight off the disease targeted by the vaccine, making it less likely you will get it, and if you do get it, you are likely to have a less severe version with fewer complications. 

There is a lot of research that shows that vaccinated children are less likely to get the vaccine-preventable diseases and are at no greater risk for other infections. Overall they are healthier and do better (have better health outcomes).

Do vaccines cause autism?

Fact: Vaccines do not cause autism. The confusion came about because in 1998 a British doctor thought there was a link between the measles, mumps and rubella (MMR) vaccine and autism. It has since been found that the doctor had changed the patient data and the laboratory reports were incorrect. The study was removed from the scientific literature and the British authorities removed the doctor’s licence to practice medicine.

There are now many well-conducted studies that have addressed this issue, and some studies have more than one million children in them. These studies strongly show no evidence of any connection between autism and the MMR vaccine, even among at-risk individuals. The MMR vaccine is very safe.

Is giving children multiple vaccines at the same time harmful?

Fact: The immune system of even very young babies can respond to many vaccines at once. The immunisation schedule is based on decades of medical evidence showing the best time for vaccines to be most effective in preventing the diseases in the schedule. Often children are most vulnerable to these diseases, so if vaccines are spread out over a longer time, there is a chance of missing the best time to protect our children.  

There are far fewer immune stimulants in all the infant scheduled vaccines combined than there are in a single natural infection. Your child’s immune system has the ability to respond to many vaccines at the same time. 

While some parents may be concerned about their child having 3 or more vaccines at one time, it is very safe to do this and their immune system will respond in a similar manner to giving 3 vaccines at separate times.

Why do I need to get my child vaccinated instead of relying on herd immunity?

Fact: Herd immunity only exists if very high numbers of people in each area get vaccinated. If several neighbours also decline vaccines for their children, your child is at risk. Also, for some diseases there is no herd immunity effect of the vaccine, so vaccination to provide protection for each person is vital.

Even where there is a high rate of vaccination, herd immunity offers no guarantees. The protective effect of herd immunity can vary based on the 'herd' that you move with. Relocation, travel or even a new circle of friends can change the composition of your herd and therefore its shared protection against infection.

Relying on herd immunity and low vaccination rates in some age groups has contributed to recent measles outbreaks in New Zealand and overseas, where many children have become very ill and some have died. 

Can the Pfizer vaccine be given with other vaccines?

Fact: The Pfizer vaccine can't be given within 2 weeks of a flu vaccine, or 4 weeks of any other vaccine, such as the MMR vaccine. Having a gap between 2 different vaccinations makes it easier to work out which vaccine may be responsible for any side effects.

Note that you need 2 doses of the Pfizer vaccine. These are given at least 21 days apart. 

If you are due for the Pfizer vaccine and the flu vaccine or the MMR vaccine, having the Pfizer vaccine takes priority over having other vaccines. It is best that the COVID-19 vaccine course is completed before receiving influenza or MMR vaccines.

Learn more

For other reliable and accurate information about COVID-19 vaccines, see:

Karawhiua A campaign for whānau, hapū, iwi and Māori communities to help prevent the spread of COVID-19, Te Puni Kōkiri (Ministry for Māori Development), NZ
COVID-19 vaccination rollout for Northland and Auckland IMAC, NZ, 2021
Getting vaccinated for COVID-19
 The Immunisation Advisory Centre, NZ
Covid-19 Education Immunisation Advisory Centre, NZ
COVID-19: Vaccine planning Ministry of Health, NZ
COVID-19 therapeutic products – questions and answers Medsafe, NZ
Facts about COVID-19 vaccines Centers for Disease Control and Prevention, US
Coronavirus disease (COVID-19): Vaccines World Health Organization
Questions and answers about COVID-19 vaccines Children's Hospital of Philadelphia 


  1. Six common misconceptions about immunization World Health Organization
  2. Vaccine myths and misconceptions Journal of the American Academy of Physician Assistants, 2014
  3. Vaccines – the myths and the facts American Academy of Allergy, Asthma & Immunology, US, 2019
  4. Offit PA, Quarles J, Gerber MA, et al. Addressing parents’ concerns: Do multiple vaccines overwhelm or weaken the infant’s immune system? 

Reviewed by

Dr Helen Petousis-Harris is an associate professor at the University of Auckland working in the area of vaccinology. Her research is focussed on the effects and the safety of vaccines. She is a member of several national and international advisory committees on vaccines.
Credits: Health Navigator Editorial Team. Reviewed By: Dr Helen Petousis-Harris, Associate Professor, University of Auckland Last reviewed: 15 Jun 2020