This Q&A was co-authored by Charlotte Milbank [@epidummyology] and Dr Hazel Wallace [founder of @thefoodmedic]
Q. How was the Covid-19 vaccine developed so fast?
The COVID-19 vaccine trials have been just the same as normal vaccine trials. Phase one, phase two and phase three . The process does typically take several years but where time has been saved is by recruiting participants in advance, so at the moment the study protocol is in place, the Ethics Committee is in place, so are the vaccine trial participants – which speeds up the process. Setting up the trial, assembling expert research teams, and applying for and securing funding can also take years under more normal circumstances.
The numbers of people in the trials were the same as you would expect for any other vaccine, and on top of that the safety assessments and the assessments of effectiveness at the end are the same – it’s the same regulators doing the same job. The Pfizer vaccine clinical trial size was around 45,000 people. These are very, very big studies including diverse population groups.
Getting into the nitty gritty of trial themselves… we’ve also been able to move fast through the final phase because of the fact that COVID-19 was so widespread at the time. When we conduct a trial, we have to reach a set “endpoint” whereby we see a certain number of cases within our trial participants. This is where we unblind our trial and see (hopefully) that these cases occurred in our placebo group. Because COVID-19 was so widespread, we could reach this endpoint far quicker than if the disease wasn’t so prevalent.
Q. How many doses of the Pfizer Covid-19 vaccine will need to be administered?
The vaccine is given in two doses – three weeks apart – and data from clinical trials showed the vaccine has 94% efficacy in protecting people over the age of 65 from coronavirus, with trials suggesting it works equally well in people of all ages, races and ethnicities. There were also no serious safety concerns reported in the trials.
PS. Efficacy in trials & effectiveness in real life do not always match up. In trials everyone received the dose required exactly on time – this may not always be possible in real life & delays in receiving the booster may reduce effectiveness.
Q. How quickly is the Pfizer vaccine effective after doses?
Full protection should begin 7-10 days after the second injection. Those who were first to be vaccinated will be immune on 6th January.
Q. Are there any side effects?
Like all medicines, vaccines can cause side effects. Most of these are mild and short-term, and not everyone gets them. For this vaccine, like lots of others, they have identified that some people might feel slightly unwell, but they report that no significant side effects have been observed in the over 43,000 people involved in trials.
Very common side effects include:
- having a painful, heavy feeling and tenderness in the arm where you had your injection. This tends to be worst around 1 to 2 days after the vaccine
- feeling tired
- headache
- general aches, or mild flu like symptoms
*These symptoms should last less than a week, if your symptoms seem to get worse or if you are concerned, call NHS 111.
Q. How can people be confident there won’t be long-term side effects?
Of course, we cannot be 100% sure. However, every single vaccine authorised for use in the UK has been authorised by the MHRA. The Medicines and Healthcare products Regulatory Agency (MHRA) is the UK’s independent regulator. Their role is to ensure medicines, devices and vaccines work effectively and are safe for use. No step has been skipped.
Rigorous monitoring of all trial participants (who have already been monitored for the 6months since the trial started) will continue for another 2 years. Robust health surveillance of the wider community also takes place after the roll-out of any licensed medicinal product and will provide immediate updates if needed. All this is “Phase 4” of our clinical trial.
Q. Is the COVID vaccine safe for pregnant or breastfeeding women?
These vaccines have not yet been tested in pregnant or breastfeeding women and therefore, as a purely precautionary approach, vaccination is not recommended if you are planning to get pregnant (in the next 3 months), are currently pregnant, or are breast-feeding. You should avoid getting pregnant for 2 months after vaccination. As we do more research, this will better inform discussions on vaccination in pregnancy.
It is important to note that this advice is based on the absence of information as opposed to the evidence of harmful effects in these groups. It is the default position for trials to exclude pregnant & breastfeeding women to avoid any increased risk to newborns or unborn children.
Q. Should we be concerned about the effect on fertility?
There is also no evidence that Pfizer/BioNTech’s Covid-19 vaccine affects fertility and trials excluded anyone that was actively trying to conceive. Again, this is a precautionary approach commonly adopted in trials.
Although we haven’t had years to watch what happens after people get the vaccine, this doesn’t mean there’s any evidence this vaccine might impact fertility. It just means that hasn’t been explicitly studied.
No previous vaccines have affected fertility.
Q. Should people who have already had COVD get vaccinated?
Yes, if they are in a priority group identified by JCVI. The MHRA have looked at this and decided that getting vaccinated is just as important for those who have already had Covid-19 as it is for those who haven’t. Increasing evidence supports that natural infection to COVID-19 does not result in long-lasting immunity and there have been several reports of re-infection.
Q. Can the vaccine cause allergic reactions?
In the last week, thousands of people have received the vaccine. Two people experienced anaphylactic type allergic reactions to the Pfizer vaccine. Both people had a history of severe allergic reactions (and carry EpiPens), both people are doing well and have been sent home from hospital. As a precautionary measure, new advice is:
Any person with a history of a significant allergic reaction to a vaccine, medicine or food (such as previous history of anaphylactoid reaction or those who have been advised to carry an adrenaline autoinjector) should not receive the Pfizer BioNtech vaccine.
The risk of anaphylaxis is very low (approximately one in a million vaccine doses) and normally occurs within 15minutes of receiving a vaccine (which is why there is now a 15 minute observation period afterwards)
Q. Will I be contacted by the NHS if I am eligible?
Please do not contact the NHS to seek a vaccine, the NHS will contact you. When you are contacted, please attend your booked appointments.
Q. Can people choose what vaccine they have?
The Pfizer/BioNTech vaccine is the first to be authorised and is being rolled out as fast as possible by the NHS across the UK. If authorised, the AstraZeneca/Oxford vaccine and other candidates will be deployed alongside the Pfizer/BioNTech vaccine to increase the pace and volume of the UK programme.
Q. Can you catch COVID-19 from the vaccine?
You cannot catch COVID-19 from the vaccine. It is not a “live” vaccine and does not contain infectious virus.
Q.Can you give COVID-19 to anyone if you have had the vaccine?
The vaccine cannot give you COVID-19 infection, and a full course will reduce your chance of becoming seriously ill. We do not yet know whether it will stop you from catching and passing on the virus, but we do expect it to reduce this risk. This is because of how the trial was run. It only looked for symptomatic cases of infection in it’s trial participants and wasn’t able to detect asymptomatic cases, who could still pass on the virus [insert graphic on this (10th December) – Preventing Transmission.]
As a greater proportion of people are vaccinated this becomes less important because the proportion of people who remain susceptible to infection reduces.
However, It is still important to follow the guidance in your local area to protect those around you.
