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A quick Q&A on the Pfizer/BioNTech Covid-19 vaccine

5 Dec 2020

We answer some common questions about the Pfizer/BioNTech vaccine, as the UK Covid-19 immunisation programme begins

At last, some good news about Covid-19! After many months of intensive research by the entire scientific community, there are now licensed Covid-19 vaccines – and more than 100 others in development. In the UK, a vaccine developed by the US pharmaceutical company Pfizer and German company BioNTech was licensed for use on 2nd December 2020.

Lots of questions are being asked about the Pfizer/BioNTech vaccine, so our Lead GP has answers to the most frequently-asked queries.

How do vaccines work?

Vaccines work in two ways – they either contain a weakened or inactive section of a virus or bacterium, or a ‘blueprint’, to be made. They can’t cause the disease. Instead, vaccines trick your body into thinking it has a particular infection so your immune system produces antibodies against it. Then, if you come across the virus or bacterium again, your body is already equipped to defeat it.

How does the Pfizer Covid-19 vaccine?

The Pfizer/BioNTech vaccine takes the ‘blueprint’ approach. It uses messenger RNA (mRNA) which is a genetic code, or ‘message’, that the human body reads to make proteins.

The Covid-19 virus has proteins studded all over the outside of its shape, giving it a spiked appearance. By using the code to these Covid-19 spike proteins, the vaccine teaches the human body to build these proteins, which are then recognised by the immune system.

Immune system cells (B cells) come across these proteins and recognise them as dangerous, so they start to produce antibodies that will directly fight against the virus. Other types of immune cells - called ‘Killer T-cells’ - also read this code and act to directly destroy coronavirus-infected cells.

The mRNA from the vaccine naturally decays and is destroyed within a few days of entering the body. It’s a ‘message’ only, and so cannot be incorporated into the human body DNA – and cannot cause Covid-19. But its work has been done, as the immune system remembers this code.

This means that if the body was to be infected with Covid-19 in the future, the immune system would react very quickly to destroy the virus and any infected cells before an infection takes hold.

Specific to the Pfizer/BioNTech vaccine is the fact that the mRNA code is enclosed in a lipid ‘bubble’ for injection – this is very fragile and destroyed easily if not kept in the correct conditions. This is why this vaccine needs to be kept at temperatures of -70C.

It’s currently not known how long the immune protection triggered by this vaccine can last. Some vaccines for other diseases provide lifelong protection, while others require ‘booster’ doses to help the immune system remember.

How was the Pfizer vaccine produced so quickly?

Covid-19 has many similarities to the SARS virus, which had an infectious outbreak in 2002-2003. Because the genetic code to SARS and Covid-19 were similar, scientists had a head start when developing the Covid-19 vaccine.

It also helps that never before in the history of vaccine development has the entire scientific community worked so hard towards a common goal – and had access to so much funding. Normally, a lot of the time it takes to produce a vaccine is taken up with applications for funding and recruitment of enough volunteers willing to take the vaccine.

There are also often difficulties with assessing a vaccine's effect, as the infection it’s immunising against may not be very prevalent amongst the general population.

With the Covid-19 vaccine, we didn’t need to worry about any of these problems. Funding was available immediately, there have been plenty of volunteers keen to test the vaccine and there’s a pandemic raging – so the efficacy of the vaccine can be easily demonstrated. All of this allowed the vaccine to be developed at great speed.

Is the Pfizer vaccine safe?

The Pfizer/BioNTech vaccine has undergone several stages of vaccine trial – phase 1, phase 2 and phase 3. Data from these vaccine trials shows that over 40,000 people have had the vaccine with no serious safety concerns.

After completing safety trials, the UK Medicines and Healthcare products Regulatory Agency (MHRA) also assessed the vaccine and its clinical trial data. The MHRA is an independent, experienced body that’s responsible for making sure UK medicines and medical devices work as they’re supposed to and are safe, following international standards of safety.

The MHRA assessed the vaccine against these strict standards of safety, quality and effectiveness, and the Pfizer/BioNTech vaccine has met all of these criteria.

Since the UK approved this vaccine for use, the only serious side effects that have occurred are very rare cases of allergy in people already known to suffer with severe allergic reactions. There have been no other reported serious side effects or long-term complications of the vaccine.

How is the Pfizer vaccine given?

The vaccine is administered via injection to the muscle of your upper arm. Two doses are required. The second dose may be given between 3 to 12 weeks after the first.

Seven days after the second dose has been given, data indicates 95% protection against Covid-19.

Are there any side effects to this vaccine?

The Covid-19 vaccine may cause side effects similar to those experienced by others, like the yearly flu vaccination. These side effects include:

  • A sore, achy arm where the injection was administered
  • Mild redness and/or swelling around the site of the injection
  • Tiredness
  • Headache

Most side effects are mild, and last no longer than a few days. The vaccine is being closely monitored for any other side effects.

When will I get a vaccine?

Currently, the vaccine is being allocated to:

  • Those aged over 80 years
  • Those who live, or work, in care homes
  • Clinically high risk healthcare workers

These are groups of people considered to be at highest risk of severe complications from Covid-19, or at high risk of passing Covid-19 on to those who are very vulnerable.

After these groups have been successfully vaccinated then the order of vaccination will be:

  1. All those aged 75 and over
  2. All those aged 70 and over, and clinically extremely vulnerable individuals
  3. All those aged 65 and over
  4. All those aged 16 to 64 with underlying health conditions which put them at higher risk of serious disease and mortality
  5. All those aged 60 and over
  6. All those aged 55 and over
  7. All those aged 50 and over
  8. All adults below 50 years old

The NHS will contact patients when they become eligible for a vaccination.

Who should not have the Pfizer/BioNTech vaccine?

Currently, the vaccine is not routinely recommended for pregnant women. This is because the clinical trial participants did not include pregnant women, and so it cannot be certain it’s safe. But, there’s also no current evidence to suggest it’s unsafe, so pregnant women who are at high risk of severe complications from Covid-19 are likely to be offered the vaccine. The guidance on routine vaccination of low risk pregnant women may evolve and change in the future.

Similarly, there’s very little data on the efficacy or safety of vaccinating adolescents, and no data on safety in young children. But it’s known that children are very unlikely to become seriously unwell with Covid-19, so it’s not currently recommended that children under 16 years are vaccinated unless they’re clinically very vulnerable (for instance, a severely disabled child living in a residential care home).

Lastly, people that have previously experienced a severe allergic reaction (anaphylaxis) should not have this vaccine.

What’s the advice on vaccines for breastfeeding women, or women attempting to conceive?

When the vaccine was initially released, it was advised that women who were breastfeeding, or planning to conceive in the next 3 months, should not have the vaccine. This guidance has now changed.

As of 30th December 2020, the Joint Committee on Vaccine and Immunisation (JVCI) has assessed the available evidence and mechanism of action in which the vaccine works, and have deemed the vaccine safe – for breastfeeding women and those trying to conceive. There’s no need to avoid pregnancy for any length of time after the vaccination.

What can I do until I get a vaccine?

Until we’re advised otherwise, and irrespective of whether you’ve had a vaccine or not, it’s important that everyone continues to abide by the guidance of ‘hands, face, space’, respects social distancing, washes their hands regularly, wears a mask when required and follows the lockdown and tier rules.

This article was written by Dr Rhianna McClymont, Lead GP, Livi.

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