What you need to know about the Pfizer vaccine

Find out how COVID-19 vaccines were developed, how we know they are effective, and how the Pfizer vaccine works.

We are using the Pfizer vaccine

The main COVID-19 vaccine we are using in New Zealand is made by Pfizer-BioNTech. It is also known by its brand name, Comirnaty.

It is an mRNA-based (messenger ribonucleic acid) vaccine.

It does not contain any live, dead or deactivated viruses. It does not affect or interact with your DNA or genes. 

AstraZeneca vaccine

If you are aged 18 years or over and either cannot get the Pfizer vaccine or want a different option, you can get the AstraZeneca vaccine.

What you need to know about the AstraZeneca vaccine

How the Pfizer vaccine protects you from COVID-19

The type of coronavirus that causes COVID-19 is new to humans. This is why our bodies do not already know how to fight it off.

How it works

  1. The vaccine sends a set of instructions to teach your body how to fight the COVID-19 virus.
  2. With these instructions, your body learns to recognise the COVID-19 virus and use antibodies against it. Antibodies stop the virus from infecting your cells and help to kill it.
  3. If you come into contact with the COVID-19 virus in the future, your body will have the right tools to protect itself so you are less likely to get sick.

Watch NZ Vaccine Facts: What is a virus and how do vaccines work?

Watch NZ Vaccine Facts: What is an mRNA vaccine?

How we know the Pfizer vaccine is effective

COVID-19 vaccines are already the most well-studied vaccines ever made.

We know the Pfizer vaccine works because it went through months of clinical testing with more than 40,000 people before it was approved for use. Clinical trials compared the results of a vaccinated group with another group who received a placebo (salt solution).

In the clinical trials, it was found that the Pfizer vaccine gave 95% protection against the symptoms of COVID-19.

COVID-19: Vaccine clinical trials and testing – Ministry of Health (external link)

Effectiveness of vaccination against variants


Being fully vaccinated gives you a high degree of protection against Delta infection, and an even higher degree of protection against severe illness, hospitalisation and death.

Evidence currently shows the effectiveness of 2 doses of the Pfizer vaccine against illness due to Delta infection is about 88%, and the protection against hospitalisation due to Delta infection about 96%.

COVID-19: About the Delta variant | health.govt.nz (external link)


Data is emerging that a booster dose of the Pfizer vaccine provides better protection than a 2-dose course against the Omicron variant. 

While 2 doses provide some degree of protection against severe disease from Omicron, a booster is likely to offer greater protection against transmitting COVID-19 to others, and reduce the chance of more serious infections.

Get your vaccine booster

COVID-19: About the Omicron variant | health.govt.nz (external link)

Watch NZ Vaccine Facts: Do vaccines work when a virus changes? (external link)

COVID-19 vaccines were developed quickly — and safely

This is the first time scientists and governments from around the world have united to develop a vaccine. This global collaboration meant vaccines were developed very quickly but without taking any shortcuts in the necessary processes or compromising safety. 

  • Scientists had a head start because of all the research already carried out on related viruses.
  • Governments, private companies and funding agencies have spent a lot of money. This means more could be done in a short space of time.
  • Researchers and governments from different countries shared information and worked together. 
  • More people than usual volunteered for clinical trials. Some clinical trials were done at the same time, instead of one after another.
  • Large manufacturing plants were built so more vaccines can be made faster than was possible before.
  • Researchers could show the vaccine worked sooner than usual, because there are so many cases of COVID-19.

Watch NZ Vaccine Facts: Are vaccines safe?

The vaccine meets New Zealand’s strict safety standards

How vaccines are approved for use

Medsafe is New Zealand’s medicines safety authority. It checks applications for all new medicines, including vaccines, to make sure they meet international standards and local requirements.

It will only recommend a medicine is approved for use in New Zealand if it meets these standards.

Medsafe has given the Pfizer vaccine provisional approval (with conditions) for use in New Zealand. This means it is been formally approved, but Pfizer must give Medsafe ongoing data and reporting to show that it meets international standards.

How we check the safety of vaccines being used

Medsafe will continue to monitor the safety and efficacy of the vaccine as it is used. It reviews data from ongoing clinical trials around the world, and reports from healthcare professionals and people who have been vaccinated.

Assessing and approving the vaccines — Ministry of Health (external link)

Common side effects

As with all medicines, you might experience some mild side effects. This is common, and a sign that your body is learning to fight the virus.

Side effects

Protect yourself from misinformation

It is normal to have questions about taking a new medicine. We all need accurate and reliable information when we make a decision for ourselves and our whānau.

There is some misleading information out there about the vaccine. You can protect yourself and others by knowing how to spot misinformation.

Learn how to spot misinformation and scams

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