There is much to celebrate about Pfizer and BioNTech’s new Covid-19 vaccine which, it was reported last week, offers more than 90 per cent protection in early data.
The vaccine trial has found “no serious safety concerns” thus far and is in the final stage of testing, known as a phase 3 trial. It may be available for a limited number of people by the end of the year.
The news of its success rate was received with worldwide jubilation, and hailed as “a victory for innovation and a global collaborative effort” by Prof Ugur Sahin, BioNTech co-founder and CEO.
But for vaccines to work, people must be willing to take them – (a take-up of at least 55 per cent, and probably higher, is thought to be needed to achieve herd immunity) – and after a tumultuous year, there are signs that some are hesitant.
Here, three medical experts answer some common questions surrounding the vaccine.
- Trudie Lang, professor of global health research at the University of Oxford, who works in malaria vaccine development and sat on the Ebola vaccine safety board
- Heidi Larson, professor of anthropology, risk and decision science at the London School of Hygiene and Tropical Medicine and director of The Vaccine Confidence Project
- Dr Michael Fitzpatrick, GP and author of MMR and Autism: What Parents Need to Know
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How can we be sure the vaccine is safe, when it’s been tested over such a short time?
Lang: The vaccine development pathways are well set out and every vaccine has to follow the same path and meet the same standards. Although it’s been incredibly fast, there definitely won’t be any short cuts. The single biggest change is how well science is collaborating and working as a collective organisation. With the Covid vaccine, we got a really good start because the genetic code was shared really quickly and the technology has already been used in cancer therapy.
And a key factor in how fast we’ve learned whether it works or not is the level of infection in the community, especially in the second wave, where there’s quite a bit of transmission.
This trial involved 43,538 people from diverse backgrounds (half of whom got the vaccine, while the rest received a placebo). That’s a good number to bring the required safety data.
Larson: New scientific technology and the funding that became available after the Ebola outbreak have made the process faster.
There are extremely rigorous safety measures around these trials. Some companies have got together and signed an agreement that says they will not be pushed by political processes.
This is an mRNA vaccine – a technology never used before for a virus, so should we have a longer testing period?
Lang: mRNA technology has been used in cancer therapy, so we are building on what we already know. This vaccine delivers a code that instructs human cells to build copies of the protein spikes on the surface of the Covid-19 virus.
Our bodies then make antibodies to these protein spikes and this allows the body to respond to a real infection.
The code can only make this specific protein and not do anything else. It can’t insert itself into our DNA, it can’t replicate and it’s not infectious.
Regardless of the technology and the urgency, it will go through the same steps as any vaccine would. During the trial, there will be a review committee of independent experts who are not part of the trial, or the drug company and, in addition to that, there are the regulators.
Fitzpatrick: The mRNA is in many respects a cleaner technology than traditional vaccines, when you’re modifying an existing strain of the virus to reduce its virulence.
Could the vaccine have unforeseeable side effects, not yet discovered?
Fitzpatrick: The answer to that is, honestly, yes. But most vaccines turn up the adverse side effects fairly quickly. The most recent serious issue was in the swine flu vaccine which led to rare cases of narcolepsy, but they turned up within a few weeks rather than six months later. I can’t think of a very long-term side effect of a vaccine.
Lang: The regulators aren’t going to approve anything they don’t think is absolutely safe, and then when it goes into general use there’s a really strong oversight process to carry on collecting safety data.
Larson: There can be side effects that show up in a particular individual, even after hundreds of thousands of people have been given the vaccine, but that would be rare. Anything more common would show up before the vaccine goes public.
Has the vaccine been tested on the over 70s, or other vulnerable groups?
Fitzpatrick: The Pfizer vaccine has been tested on people as young as 12 and up to the age of 85 and also on black and ethnic minority groups.
In the older age groups, vaccination is always an uncertainty because their immune system tends to be less responsive. It could be they wouldn’t get a response or would be more affected by side effects.
The phase 3 trial has also included people with chronic, stable HIV, hepatitis C and hepatitis B. It will be tested in other populations after the phase 3 trials are completed.
Lang: The MHRA (Medicines and Healthcare products Regulatory Agency) will absolutely want to see safety data for every age group that is going to be given the vaccine, and will expect data across ethnicity and underlying disease. The regulators will only approve the vaccine for groups where they have the data.
Will children have it? Aren’t their immune systems too immature?
Lang: If they were going to immunise children they would need to do a whole paediatric testing programme and since children don’t really get ill, you would only be vaccinating them to prevent transmission in the community.
Fitzpatrick: As far as I know, there are no plans to give children the vaccine at the moment.
I don’t think it’s a question of the maturity of the immune system. Children’s immune systems are pretty active, that’s why we give vaccines to babies.
It’s more a question of logistics, and the relative impact of the disease. One of the few positive things about the coronavirus is that it doesn’t affect children as much as adults.
Shouldn’t we wait for a vaccine that’s 100 per cent effective?
Larson: No. It’s extremely rare for any vaccine to have 100 per cent efficacy – 90 per cent is already high.
Fitzpatrick: Ninety per cent is fantastic. It’s way more than the current vaccines we use in flu, which are only 40-50 per cent effective.
The data from the Pfizer trial hasn’t been published in a peer-reviewed medical journal yet. Is there a danger of getting our hopes up too soon?
Lang: The data they’ve released is only interim analysis, but this trial will absolutely go on and be submitted to a peer-reviewed journal. But what’s more important is that the regulatory bodies will interrogate the whole body of data. When a scientist submits to a journal, they can choose what they include. But when you submit to a regulatory body, – the MHRA, the FDA or EMA – you have to send absolutely everything, the good, the bad, the whole lot.