Your COVID-19 vaccine questions answered

Dr Unnati Desai Dr Unnati Desai National Lead for GP Services
With the Pfizer/BioNTech vaccine being rolled out this week, Dermatology Lead and GP Dr Unnati Desai tells us everything we need to know about vaccines, including those for COVID-19.

What is a vaccine?

Vaccines work by preparing your immune system to recognise and fight off the specific virus or bacteria (pathogen) they are targeting.

Vaccines contain part of the pathogen in order to trigger the body’s immune response to create the IgG antibodies needed to fight off the infection that particular pathogen would otherwise cause.

While COVID-19 vaccines are designed to treat the virus by helping you create the right antibodies, the COVID-19 antibody test simply tells you whether you’ve had the virus or not, depending on the presence of antibodies in your system.

Vaccines currently in use are either:

  • live attenuated – using a weakened form of the whole pathogen; or
  • inactivated – using either the whole pathogen that has been killed, or small protein parts from viruses or sugar parts from bacteria that cannot cause disease.

Live attenuated vaccines

These replicate in the body, but won’t cause disease in healthy people. They can result in the vaccinated person feeling unwell for a few days and this tends to be a very mild illness.

This type of vaccine tend to create a strong, long-lasting immune response, as it’s virtually identical to the response produced by a natural infection. One to two doses are usually enough to provide immunity with the IgG antibody.

Live attenuated vaccines aren’t recommended for people with a weakened immune system because replication can’t be controlled, and may cause the disease.

Inactive vaccines

These vaccines don’t replicate in the body and won’t cause disease in people, even with a compromised immune system.

Inactive vaccines always require multiple doses weeks or months apart. Immunity with the IgG antibody usually occurs after the second or third dose, and may also require boosters throughout life.

How do vaccines work?

Vaccines train your immune system to create IgG antibodies and decrease your risk of getting the actual disease.

When vaccinated, your immune system responds by:

  1. Recognising the pathogen and the antigen (the foreign proteins on the surface of the pathogen)
  2. Producing antigen-specific antibodies
  3. Keeping a blueprint of the IgG antibodies so that if you’re exposed to the pathogen in the future, your immune system can quickly destroy them without you getting unwell.

How effective are vaccines and how do they provide herd immunity?

No vaccination programme is 100% effective, as some people won’t be able to have a vaccine if their immune systems are weak. There may also be some who are severely allergic to components in the vaccine, or those who just don’t respond to the vaccine.

Herd immunity occurs when a large enough proportion of the population has been vaccinated successfully. It’s hard for pathogens that are spread from person to person to be able to exist in a vaccinated community.

Is there a vaccine for COVID-19?

The Pfizer/BioNTech vaccine is the first to be approved in the UK, but there are currently over 250 COVID-19 vaccines under development globally, of which 48 are in clinical testing. Some are being developed with traditional techniques, while others have been created using new methods.

The vaccines likely to be available soon, including the Pfizer/BioNTech vaccine, are based on new ways of developing vaccines, which use the genetic material of the virus. These are quicker to create than vaccines made through traditional methods and the results of human clinical trials have been very promising.

The vaccines based on traditional methods, created from inactive whole viruses or protein parts of the virus, will likely be available later in 2021.

All COVID-19 vaccines will be administered by an intramuscular injection and will require 2 doses.

Will it be safe to have the COVID-19 vaccine?

A new vaccine usually takes several years to develop, as scientists will work independently and each step of the process will be done in a specific sequence. The COVID-19 vaccines has been created quicker due to a global collaboration of scientists, and each stage of the process has been done in parallel – without compromising vaccine safety.

COVID-19 Clinical trials

The clinical trials have shown that the vaccines are safe across all adult age groups, with fewer local and systemic reactions (localized redness and swelling at the site of the injection, headaches, fever, tiredness and muscle pains) in older patients and good immune responses across all ages.

The top 3 vaccine developers that have already gathered data from phase III clinical trials (trials that involve thousands of people once the developers have safely completed phase I and II clinical trials, which are on smaller groups of people), include:

  1. Pfizer and BioNTech
  2. University of Oxford and AstraZeneca
  3. Moderna and US National Institutes of Health

Safety regulators

Final safety checks are currently being taken by the Medicines and Healthcare products Regulator in the UK (MHRA) who must approve any vaccine prior to it being used in the UK.

Once a vaccine has been made available for use in the UK, the safety of the vaccine will continue to be monitored by the healthcare professionals and the MHRA in the UK, but also globally by the manufacturers, other MHRA-equivalent organisations internationally, and the World Health Organisation, who send any relevant data to the MHRA.

At the time of writing this article, the UK government has secured over 357 million vaccine doses from seven different developers, which will be made available quickly once approved by MHRA. As of 2 December 2020, the government accepted MHRA’s recommendation to approve the first COVID-19 vaccine in the UK from Pfizer and BioNTech.

Is there an alternative to the COVID-19 vaccine for people who can’t take it?

There’s a trial in progress looking at an injection of two COVID-19 antibodies. This will likely be available for people who:

  • have a weakened immune system and would not be safely able to have the vaccine created from viral genetic material;
  • require immediate protection; and
  • don’t respond to the other vaccines.

If successful, this will be used alongside the COVID-19 vaccines and not in place of it, as the immune response from the vaccine will be stronger for the prevention of disease.

It may take some time to roll out the vaccine

The news of the Pfizer/BioNTech vaccine being rolled out is very encouraging, however it may still be a while before the whole of the UK is vaccinated. The vaccine is being offered in order of priority, with those in care homes, older people and vulnerable people higher up the list.

In the meantime, if you want to find out whether you’ve had the virus, our COVID-19 antibody test is available now.


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UK authorizes Pfizer/BioNTech COVID-19 vaccine. GOV.UK News story: 2nd December 2020.

Last updated Monday 7 December 2020

First published on Monday 7 December 2020