The Pfizer vaccination schedule requires two doses into the deltoid muscle at the top of the arm, 21 days apart.

How does it work?

This vaccine technology (nucleic-acid vaccine) involves using a small part of the Covid-19 genetic code, called mRNA, as a messenger to the body. It provides instructions for human cells to produce the coronavirus “spike” protein – the specific, spike-shaped protein that is unique to coronavirus.

Once the body produces this spike protein, the immune system produces antibodies and activates long-lived memory cells. After vaccination, if a person is exposed to coronavirus, the body will immediately recognise the “spike” and trigger an immune response to overcome and destroy the coronavirus.

The advantages of this process are that there is no risk of the vaccine causing the disease you want to eliminate, and the vaccines are quick to produce. The downside is they need specific, strict storage conditions.

How is the vaccine made?

Flu vaccines are often created in newly embryonated chicken eggs. Basically, the flu virus is injected into every single egg, grown to large quantities and then chemically deactivated. That’s a lot of time-consuming steps in the lab.
By contrast, mRNA uses no eggs and no chickens. What’s being injected are just genetic instructions for the human body to make its own virus protein, which then triggers its own immune response to crank out antibodies.

What is in the vaccine vial?

Some people have vaccine hesitancy because they don’t understand exactly what is in a vaccine. A lack of understanding can lead to suspicion, which can result in the spread of misinformation and affect confidence in getting the vaccine and undermine efforts to achieve a high uptake.

The Pfizer vaccine has very few components. It contains four lipids (fats) that protect the surrounding genetic code (RNA) – a bit like a protective wall – so the code does not break down before it is injected into a recipient.

There are four salts in the vaccine. This is so the vaccine most closely mimics the pH of the human body. We don’t want the body to destroy the code as soon as it is injected.

Finally, there is some sucrose (sugar), which stops the lipids sticking to one another, helping to maintain a consistent suspended solution.

Sometimes there is reluctance about getting vaccines due to the mistaken belief that “toxins” get injected when we are vaccinated. Components such as animal products, antibiotics, blood, DNA, egg proteins, live viruses, aborted foetal products, mercury or soy are commonly cited as being hidden components within vaccines. The Pfizer vaccines does not contain any of these components.

FAQs

Can I trust that the vaccine is safe and effective?

One advantage of observing other countries during the vaccine rollout is being privy to the continuous post-administration safety data being collected around the world.

Internationally, tens of thousands of participants were enrolled in the Phase 3 trials. To date, the Pfizer vaccine has been administered to millions of people across many countries and the data to date suggests it is safe.

The United States has delivered more than 47 million doses and Britain has given 15 million doses. There is mounting proof that the evidence around safety, gathered during clinical trials, reflects the real-world experience.

Once individuals are immunised there are ongoing safety surveillance systems around the world that have been in place for decades. These systems pick up any “red flags” in the programme. If, for example, surveillance systems noted increasing local reactions, that would prompt action for recall or ring-fencing vaccine batch numbers until an investigation could be done.

We also have an excellent medicine safety surveillance system in New Zealand.

Before approval for human use, the Pfizer vaccine underwent Phase 1, 2 and 3 clinical trials in the US, Germany, Brazil, Argentina and Turkey.

The vaccine has been shown to be 95 per cent protective against symptomatic Covid-19 two months after the second dose.

Studies are ongoing to determine exactly how long after the two-dose regime a person will remain protected. Not enough time has passed since the clinical trials started to accurately assess the duration of protection. Boosters may be required, but, right now, it is simply too soon to tell.

What side effects can I expect after the vaccine?

If you have ever received a vaccine before, you may recall that sometimes you become aware of some side effects in the following days. This vaccine is the same.

Clinical trials indicate that the most common side effects people experience following the Pfizer vaccine are pain at the injection site, a headache and fatigue. Not everyone will experience the common side effects, but it is likely you will notice one or more of them.

Other reported, less common reactions were muscle aches, generally feeling unwell, chills, joint pain, nausea and a raised temperature.

Is there anyone who shouldn’t have the vaccine?

You should not be vaccinated if:

• You are currently isolating or experiencing symptoms of Covid-19. (You can be vaccinated after you have been tested, recovered and met the criteria to stop isolating).
• You have a known severe allergic reaction to any component of the vaccine.
• You are under 16 years old.
• You have received an influenza vaccine within the previous two weeks.
• You have received any other vaccine within the past four weeks.

Some people should seek the advice of their health provider before getting vaccinated. For example:

• You have had a previous severe or immediate allergic reaction to any other vaccine. If you do choose to receive the vaccine, you will be asked to wait onsite after the vaccination for 30 minutes to ensure your safety.
• You are pregnant. You may choose to be vaccinated after consulting with your health provider to weigh up the risks and benefits of vaccination in your case. Pregnant women were not included in the clinical trials; however, we do know women are at higher risk of experiencing poor outcomes should they contract Covid-19 during pregnancy.
• Breastfeeding women were not included in the clinical trials, as with all vaccine trials. However, no obvious risks or concerns for breastfeeding women to date have been highlighted.
• Anyone on anticoagulant medication.
• Anyone on immune checkpoint inhibitors.

What happens after being vaccinated?

If you are experiencing unwanted side effects, reaching for Panadol or ibuprofen may not be the best thing to do for your immune response. The Centres for Disease Control (CDC) and Prevention in the US has said you can take this medication, but it could diminish the level of immunity that develops. The advice is to only use Panadol or ibuprofen post-vaccination if you really need it.

If you don’t get the second dose exactly 21 days after the first dose, don’t panic.
The advice from our Immunisation Advisory Centre is to receive the vaccine at the “earliest opportunity” after 21 days. The CDC allows for a four-day “grace period”, which means that receiving the second dose of Pfizer vaccine either four days before or four days after day 21 is still considered on time.

If you miss the grace period cut-off, you do not need to repeat the first dose. Just get the vaccine as soon as you can, but be aware that you may not receive the highest levels of protection demonstrated in clinical trials.

You can expect some immunity after the first dose, but maximum protection will most likely be achieved around one week after your second dose.

Lastly, we don’t yet know if the Pfizer vaccine prevents infection, or only prevents people experiencing symptoms of the disease.

If the mRNA vaccines only prevent symptoms, a person could be infected following an exposure and potentially spread the virus. Additional studies will determine whether the vaccines prevent infection as well as disease.

Given the uncertainty, vaccinated people will still need to use masks and practise social distancing measures for some time.

The future?

In the long-term, the only feasible means to achieve acceptable control of this virus will be through an effective immunisation programme. No virus has ever been eliminated by inducing widespread natural immunity in a large percentage of the population. We can all play our part by receiving the vaccine and encouraging others to do the same to achieve high vaccination coverage rates in our communities.

Helen Hartley has more than 20 years’ experience as an Authorised Vaccinator and has worked in immunisation specialty roles for 15 years. She recently completed additional training to add the Pfizer vaccine to her scope of practice.

The information in this article is from evidence-based, reputable Government websites and IMAC (NZ Immunisation Advisory Centre, Auckland University) training packages.