With the news that the UK has approved the first vaccine for COVID-19 this piece will look specifically at this one, made by Pfizer-BioNTech. (1) (2)
Previous pieces have discussed the background to vaccine research and how vaccines work. Click here to read "The Search for a Vaccine" and here to read "The Race for a Vaccine" for more information about vaccine development. The piece here "Vaccine Update and FAQs" addresses commonly asked questions.
How big was the Pfizer-BioNTech trial?
The initial safety trial, a phase 1/11 trial, involved 60 people aged 16 to 55 years. This trial sought only to ascertain if the vaccine appeared to be safe in humans. Having passed this stage the research progressed to a phase III trial to look for how well it protected recipients from COVID-19.
The phase III trial recruited around 44,000 people with 21,720 receiving the vaccine and 21,728 receiving a placebo injection. In the vaccine arm of the trial 40% of participants were aged 56 or over and 20% were aged 65 or older.
Of those who received the vaccine 51.5% were male and 48.5% were female; 82.1% were White, 9.6% were Black or African American, 26.1% were Hispanic/Latino, 4.3% were Asian and 0.7% were Native American/Alaskan native. (The percentages add up to more than 100% because some people had mixed heritage.)
Participants were then followed up to see who might develop COVID-19. Nobody was deliberately infected with COVID-19, researchers waited to see who, if anyone, caught the infection over the next few months. The bench mark was set at needing a total of at least 164 cases of COVID-19 before analysis could take place.
Researchers found that eight people who received the vaccine subsequently caught COVID-19 whereas in the placebo group 162 people caught COVID-19.
Statistically this means that the vaccine was 95% effective in preventing COVID-19. (3)
Side Effects
All vaccines and drugs can have side effects so there will never be a scenario where anyone can claim there are no side effects. The key thing is that those side effects are mild, self-limiting and far less of a concern than the disease itself.
The main side effects reported in the vaccine trials were:
Pain at the injection site - 80% participants
Fatigue - 60% participants
Headache - 50% participants
Myalgia (muscle pains) - 30% participants
Chills - 30% participants
Arthralgia (joint pain) - 20% participants
Pyrexia (high temperature) - 10% participants
All side effects were described as "mild" or "moderate" by participants and eased on their own or by taking paracetamol or a similar medication. Side effects resolved within 2 to 3 days of vaccination.
Based on this, the patient information leaflet for the Pfizer vaccine contains the following with regard to the most common side effects:
Very common: may affect more than 1 in 10 people
Pain at injection site
Tiredness
Headache
Muscle pain
Chills
Joint pain
Fever (4)
Side effect comparison with flu vaccine
To give some background context to this it is helpful to compare the same section in the information leaflets for flu vaccines, which many people are familiar with and have each winter. The flu vaccine's side effects are listed as:
Very common: affects more than 1 in 10 people:
Headache
Fatigue
Vaccination site pain
Common: affects 1 to 10 people in 100:
Sweating
Muscular pain (myalgia)
Joint pain (arthralgia)
Generally feeling unwell (malaise)
Shivering (5)
As can be seen there are a lot of similarities in the side effect profiles of both vaccines which perhaps is not surprising as they are both for respiratory illnesses.
Is there anyone who can't receive the vaccine?
At the moment the vaccine has not been approved for anyone under 16 years old, or women who are pregnant or breastfeeding. For ethical reasons vaccine trials are not carried out in children or pregnant women so it is the norm for a vaccine not to be approved initially for these groups.
This usually changes with time as more and more people are vaccinated allowing more extensive data to be collected.
The EU says the UK has rushed this, the UK says it hasn't...what is the truth?
The UK is the first country to approve a vaccine for COVID-19. This has attracted both praise and criticism from around the world.
The EU strongly criticised the UK accusing it of compromising safety in its rush to approve the vaccine and said it would base its own approval on more evidence. The UK strongly refutes that it has made any compromises. (6)
From a scientific point of view the EMA (European Medicines Agency) and the UK's MHRA (Medicines and Healthcare products Regulatory Agency) will have received exactly the same data at the same time from Pfizer both in quality and quantity. There is no more data due for release to either agency.
The MHRA has been working from June preparing the groundwork for a vaccine so that when the data finally came it had already put everything in place to allow a swift and rapid response. The MHRA is well respected worldwide and known for insisting on the highest standards of safety, quality and effectiveness for any drug or vaccine. (7)
In the UK, once a vaccine has been approved for use, the JCVI (Joint Committee on Vaccination and Immunisation) advises on the practicalities of how the vaccination programme should be rolled out. It decides, for example, who should be prioritised for the first batch of vaccines based on what is known about the illness. The JCVI is a body of practising doctors and also lay people, not politicians. (8)
Brexit has not played a role in either vaccine approval or vaccine delay. Any country in the EU can give emergency approval to the vaccine, it does not need to wait for the EMA.
Germany expects to approve the vaccine by mid-December with mass vaccinations beginning soon after, the Netherlands and Sweden are both aiming to begin mass vaccinations in the first week of January 2021. (9) (10) (11)
The US also appeared to criticise the UK's speed of approval when Dr Fauci, director of the US National Institute of Allergy and Infectious Diseases, was asked for his opinion. However, Dr Fauci has since apologised publicly saying his comments has been misunderstood. The US hopes to start vaccinating this month and before Christmas. (12) (13)
The First Recipients
The JVCI in the UK have recommended that people age 80 and over be vaccinated first followed by frontline NHS staff. One in five of all people aged 80 and over who contract COVID-19 require hospitalisation. Protecting this group first also protects the hospitals from becoming overwhelmed and, if hospitals can function normally, then other treatments such as chemotherapy and elective surgery can go ahead as planned. (14)
Some have argued that many of the elderly are not fit enough for admission to intensive care units and mechanical ventilation and that therefore they should not be admitted to hospital in the first place. However, whilst a person may not be a candidate for mechanical ventilation in hospital, staying at home, or even in a care home, when severely respiratory compromised is not often an option. When people are struggling to breathe and are extremely unwell they need admission for control of their symptoms even if it is clear that COVID-19 is a terminal event for them. (15)
Where next?
Of all the promising vaccine candidates for COVID-19, the Pfizer-BioNTech one is the most difficult in terms of storage and administration. It must be kept at -80’C and very detailed rules followed for its preparation once it has been thawed. At the time of writing we are still waiting to hear the decision of the MHRA on the vaccines by US company Moderna and the UK one from the Oxford-AstraZeneca team. The latter in particular is very easy to store and administer, if it gains approval it is likely to be the main vaccine used in the UK.
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