Frequently Asked Questions about the COVID-19 Vaccination: Updated November 2021

Please note: COVID-19 is an evolving global situation with ongoing worldwide research. If the Ministry of Health or Immunisation Advisory Centre release any updates pertinent to information contained in these FAQs, we shall link to them here.  

What are the ingredients of the Pfizer vaccination?

The Pfizer vaccine contains: 

  • Messenger RNA that encodes for the spike protein which is on the outside of the virus that causes COVID‐19
  • Fats 
  • Salts 
  • Sugar

    The vaccine does not contain DNA, fetal material, blood products or any products derived from animals or human cell lines. A full list of ingredients is available here

How does the vaccine work?

mRNA is the recipe that your body uses to instruct cells to make proteins. When the mRNA vaccine is injected into the arm, it tells the cells to make the "spike protein" which is a part of the outside of the virus that causes COVID‐19. After this, the cells rapidly break down the mRNA. 

The body identifies that the spike protein is foreign and responds to it accordingly, forming immunity and a memory of what the spike protein looks like, therefore if the cells see it again in the future the immune cells act quickly and destroy the virus. 

 The mRNA vaccine does not enter the nucleus of your cell and it cannot alter your DNA. The vaccine cannot cause COVID‐19 infection. 

Read more here at IMAC, and here at Ministry of Health.

How effective is vaccination against COVID‐19 for preventing severe illness?

Studies* have shown that 2 doses of the Pfizer vaccine are approximately 80‐97% effective at protecting against severe illness from COVID‐19. 

Figures from areas with good vaccine coverage show that those who are fully vaccinated, with normal immune systems, are largely protected from dying of or needing hospitalisation from COVID‐19 illness, whereas those who have not been vaccinated continue to have high death and hospitalisation rates. 

Estimates suggest that 127,599 deaths and 24,144,000 infections have been prevented in the UK as a result of the COVID-19 vaccination program, up to 24th September 2021.

Aotearoa New Zealand's emerging experience reflects that hospitalisations with COVID-19 are much more common in people who are not vaccinated. As of 28th October, only 1.3% of hospitalisations due to COVID-19 are in fully vaccinated people, even through the majority of the population is now fully vaccinated.

 For more information, read here.

* See page 4 of linked document. 

Will the Pfizer vaccine stop me passing on COVID‐19 to other people?

The most recent evidence shows that receiving 2 doses of the Pfizer vaccine reduces the chance of contracting and transmitting COVID‐19.

The Pfizer vaccine reduces the change of getting COVID-19 infection. If you don't have COVID-19, you can't pass it on to the other people.

A recent Norweigian Study looking at samples from both symptomatic and asymptomatic individuals showed that those who were vaccinated were two-thirds less likely to be infected with Delta compared with unvaccinated individuals.

Although cases of "breakthrough" COVID‐19 can occur in people who are vaccinated, they are usually mild. Such "breakthrough" cases may pass COVID‐19 on to someone else, but at a lower rate than transmission from people who are not vaccinated.

 Therefore, the current recommendation is that vaccinated people should continue to practice good public health measures such as physical distancing, washing hands and wearing masks.

Read more about this evidence from here at IMAC, here on New Scientist and here at the Ministry of Health. 

What are the side effects of the vaccination?

The data shows that the overwhelming benefits of vaccination with Pfizer vaccine outweigh the risk of experiencing a side effect. The majority of side effects are mild and short‐lived. They include discomfort at the injection site, feeling tired, muscle aches, headache, joint pain and nausea. Some patients describe feeling generally unwell for a day or two. Brief swelling of the lymph nodes in the armpit may also occur. 

Severe immediate allergic reactions (anaphylaxis) are extremely rare but are closely monitored for and easily treated if they occur. All vaccination centres are equipped to deal with anaphylaxis if it occurs. 

There have been rare reports of temporary inflammation of the heart wall (myocarditis), mainly in young men (under 30 years) at a rate of 1 in 25,000 in this gender/age group, and even less at 1 in a million doses in other age groups. People who develop chest pain, shortness of breath or feeling of a racing or pounding heart in the days following the vaccine should seek medical attention for assessment, ideally through their GP if possible. Fortunately, cases of myocarditis after vaccination are almost always mild and improve on their own. However, if myocarditis is diagnosed, careful assessment and monitoring is required as myocarditis can very uncommonly be serious. 

Myocarditis is seen in people with COVID‐19 infection, at a much higher rate than is seen with the vaccine. 

 Temporary one‐sided facial weakness may also rarely occur following the vaccination although some studies indicate this is no higher than occurs in the population with no vaccination. 

 Read more on here for guidance from Australia, here at the Ministry of Health or here at IMAC.

How were the vaccines developed so quickly?

Messenger RNA, or mRNA, was discovered in the early 1960s with the potential for it to be used for the treatment of human disease being recognised in 1989. Since then, research as a cancer therapeutic and an HIV vaccine, along with the development of technologies for vaccine delivery facilitated the rapid development of the first approved mRNA SARS_CoV-2 vaccine in 2020. 

When the pandemic occurred collaboration between scientists, governments and funding bodies allowed the final stages of the vaccine development and trials to be prioritised due to the importance of dealing with the severity of the global pandemic. 

The vaccine still underwent the same trials you would expect with phase one, two and three trials performed. No short cuts were taken. 

The speed of the trials was aided by the fact that recruiting volunteers for the vaccines was quicker than it often might be, due to the interest and need for a vaccine. The high incidence of COVID‐19 in some countries also meant that it was possible to see the efficacy in vaccinated people quickly as exposure to COVID‐19 in some of the trial countries was such a common occurrence. Due to the pressing need, manufacturing plants were built to produce the vaccine and reduce wait time. The result was a very efficient vaccine development that occurred at a time of global need. 

 Read more here at Ministry of Health, and here at IMAC.

How is the safety of the COVID‐19 vaccine being monitored?

As of 1st November 2021, more than 7 billion doses of the various COVID-19 vaccines have been administered around the world. The Pfizer vaccine has been administered to hundreds of millions of people throughout the world nearly 7 million doses in Aotearoa New Zealand. 

Internationally and locally, a large amount of data has been collected. Aotearoa New Zealand is leading a collaborative global initiative called the Global Vaccine Data Network, which collects data from over 17 countries to monitor vaccine safety. Such large numbers allow detection of even extremely rare side effects. In addition, Medsafe continues to closely monitor data about the safety of the Pfizer vaccine across the world, and here in Aotearoa New Zealand and produces weekly reports. In Aotearoa New Zealand, any adverse events occurring after immunisation are encouraged to be reported to the Centre for Adverse Reactions Monitoring (CARM). Reports can be submitted by a health professional or a member of the public.

Because a symptom or event in the weeks after a vaccine may have occurred despite the vaccine and may not be related to the vaccine, a team investigates these reports and looks at whether the rate of any events is higher than would be expected to happen normally. When something is happening at a higher rate than would be expected, this is called a 'safety signal' and this is then investigated more thoroughly. 

Read more about the Global Vaccine Data Network here.

If I have had COVID‐19 infection and recovered, should I still get the vaccine?

Yes. The immunity resulting from natural infection is quite variable and wanes over time. Getting vaccinated after already having COVID‐19 infection further reduces the risk of being reinfected by COVID‐19. 

 Read more here at Healthline, and here at IMAC.

Can I have the vaccine if I am pregnant or trying to get pregnant?

Yes. We know that women who are pregnant are at an increased risk of complications from COVID‐19 infection. Recent data from the UK show that up to 20% of the most critically ill patients with COVID-19 are pregnant women who have not been vaccinated. In addition to the increased risk of severe illness in pregnant women with COVID-19, their babies are more likely to be born early, be delivered by Caesarean section, and require neonatal intensive care.

Therefore, pregnant women are a priority group for COVID‐19 vaccination and can receive it at any stage of pregnancy.

Women who are trying to become pregnant do not need to delay vaccination or avoid becoming pregnant after receiving the vaccination. 

Vaccination in pregnancy can also provide some protection against COVID-19 to the baby. 

A large number of pregnant women have received the vaccine and there have been no additional safety concerns. There is no evidence of increased risk of miscarriage or birth defects with the COVID‐19 vaccine. Global evidence has shown that the Pfizer vaccine is safe for pregnant women. 

Read more here at IMAC, and here at the Ministry of Health. 

Can I breastfeed after receiving the vaccine?  

Yes. COVID‐19 vaccination can provide protection against COVID‐19 to babies by transferring antibodies through breastmilk. Studies show there are no additional safety concerns or issues with continuing to breastfeed after vaccination. Some women who have tiredness or other side effects after the vaccination may need some extra support in the following days.

 Read more here at the Ministry of Health.

Can the Pfizer vaccine affect fertility or future babies?

No. There is good evidence the vaccine does not affect fertility or future pregnancy/babies. There is not any plausible biological reason why it should. 

Read more here at IMAC and here at The Conversation.

Who should not receive the COVID‐19 vaccine?

It is rare to not be able to get the Pfizer vaccine. 

Because the Pfizer COVID-19 vaccine has an excellent safety profile, there are probably less than 100 people in Aotearoa New Zealand who cannot receive the first dose of the vaccine. 

Severe immediate allergic reactions (anaphylaxis) to the Pfizer vaccine are extremely rare. People with a history of anaphylaxis to previous COVID-19 vaccination or to any of the ingredients should ideally be referred to an immunology clinic or a clinic dealing with COVID-19 vaccine allergy for expert input. There is increasing evidence that many people with previous suspected allergies to the vaccine or the ingredients can get vaccinated safely with expert advice and a specialist clinic for administration. Patients who have anaphylaxis with the Pfizer COVID-19 vaccine, or an ingredient in that vaccine, can safely have another COVID-19 vaccine such as Astra Zeneca once it is available. 

Allergy to other substances/medications is not considered a significant risk factor for anaphylaxis to the COVID-19 vaccination. If myocarditis/pericarditis is confirmed by a doctor after the first dose of the Pfizer COVID-19 vaccine, they should forward the clinical details to IMAC at so the name of the person can be added to a list for the alternative vaccine when they become available.  

The list of relatively few other medical conditions for which vaccination may be temporarily contraindicated or deferred can be found here. 

Those who have medical concerns about receiving the vaccine or events following their vaccination should be referred to IMAC by their doctor for advice at For some of these conditions, an alternative vaccine may be appropriate once one becomes available. 

Read more here at IMAC. 

If I have cancer or my immune system is impaired can I have the vaccine?

Yes. Immunocompromised people, people with cancer and people with HIV can all receive the vaccine. 

There has been a lot of work looking into the vaccine for patients with cancer or an impaired immune system. The vaccine remains safe for these patients. In fact, because of their suppressed immune systems, it is even more important for them to be vaccinated. The response to the vaccine, however, may not be as strong as for other people. 

People with suppressed immune systems are at risk of more severe COVID‐19 disease if they catch it. For these reasons it is very important that people close to those with cancer or impaired immune systems are vaccinated, and that we have good community rates of vaccination. 

We suggest people on pulses of immunosuppression/chemotherapy discuss the timing of the vaccine with their doctor. It may be possible to time the vaccination correctly with rounds of treatment to allow the best immune response to the vaccine. 

 Read more here and here

Who can get the third primary dose of the vaccine?

People with severe immunosuppression, as detailed on the Ministry of Health website, can receive a 3rd dose of the vaccine at least 8 weeks after the second dose, as these people may not have mounted a good immune response to the initial vaccinations. An additional dose has been found to improve this immunity. A prescription and a specific consent form signed by both the doctor and the patient is required. 

Information and a consent form can be found here, or to go straight to the consent form, click here.  

Information for health professionals can be found here