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Are Covid-19 vaccines safe and how will they work?

<span>Photograph: Geber86/Getty Images</span>
Photograph: Geber86/Getty Images

On Wednesday, the UK approved the Pfizer/BioNTech Covid vaccine – those most at risk will start receiving it later this month. Over the past few weeks, successful results have also been announced in trials of other Covid-19 vaccines. And while this news has been largely welcomed by the public, many want to know if they have met strict standards of safety and effectiveness and how they have been developed so quickly.

Prof Sir Terence Stephenson is chair of the Health Research Authority, the government body responsible for ethics review and approving research proposals relating to health, and for promoting transparency in research. Here, he explains how researchers have managed to develop Covid-19 vaccines in record time, and how these vaccines will work.

It normally takes years to develop a vaccine. Could you explain how scientists have managed to develop Covid-19 vaccines so quickly?
Let’s look at what would normally happen. One: researchers have to think how they’re going to make the vaccine, do some research in the lab and then come to the Health Research Authority (HRA) for approval to start doing the research on people. Before lockdown, our research ethics committee would be convened to meet in one place, so you’d have to find a date they could all meet, they’d have to travel there, or they might meet and not reach a conclusion and have to meet again. All of that has been telescoped by virtual meetings. Nobody has to travel anywhere.

Two: we often have queries, so we go back to the researchers. They may be developing several drugs for a pharma company, and [replying] might not be their number one priority, so it could take weeks or months. During Covid-19, they’ve been addressing the query the same day or the next.

Three: the UK public have been absolutely fantastic about stepping up to the plate to be involved in research studies. A quarter of a million people signed up very quickly to volunteer for vaccine studies. Pre-Covid, you would have to recruit people.

Four: all of the pharma companies are competing to get their vaccine out first, because they can patent a vaccine.

Can we feel reassured that no corners have been cut, and that safety procedures are still being observed?
Yes, the public can be absolutely reassured, because although each of those projects has been done quicker, we’re following the same process. The HRA has played a crucial part in Covid-19 vaccine research by helping these vital studies start quickly. A lot of non-Covid research has been stopped, so we haven’t had to deal with lots of applications for research.

Our statutory responsibility is to promote research and protect the public. By sticking to our high ethical standards and our pre-Covid processes, we’ve protected the public. We’re just doing it more quickly, in a more efficient way.

A variety of vaccines are being tested in the search to find those that are effective. Why have there been so many different studies?
Until a decade ago, we either used killed virus vaccines – you kill the virus and then you inject it, and people have an immune response – or used a live, attenuated viral vaccine, which means you breed the virus and the virus evolves so that it’s harmless to humans.

What’s changed in the last decade is two new technologies have been developed to create vaccines. You can now put the genetic code of a virus, its DNA, into another virus. For example, you can put a little bit of the coronavirus code into another virus called an adenovirus, which causes the common cold. You inject that into the body, and it instructs the body to make a coronavirus protein called a spike protein. The body sees that and says: “That’s foreign, I need to make some antibodies to this.”

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Even more cutting edge is the technology that BioNtech/Pfizer and Moderna have used. They don’t put the viral code in, they put in RNA, which is the messenger. When a virus infects you with its DNA – coding for the proteins it needs – the DNA is changed or copied in RNA. The RNA is like a postman that goes around the cells in your body and causes you to make this spike protein. So you can skip a stage: you can inject RNA, and your body makes the spike protein, and says: “Whoa, this is a foreign protein, I need to defend myself against this and make antibodies.”

Nobody knows at the outset whether any of these ways of developing a viral vaccine will work, so we’re fortunate that these are already showing that they work. It’s good news.

Is there an advantage to a vaccine that uses messenger RNA (mRNA), rather than, for example, the Oxford/AstraZeneca vaccine, which uses the DNA approach?
The big advantage of the mRNA vaccine is that it is easier to make. The technology is simpler. It’s easier to produce large amounts at lower costs compared with putting the DNA inside the adenovirus. But all these things are leading to a protein being made that your body recognises as non-human and makes antibodies against it, so they all have that final pathway.

Two of the vaccines whose results have been announced so far have shown an effectiveness of 95%. What does that mean in practice?
For a vaccine trial, you recruit a group of volunteers who are healthy and well, and give half of them the trial vaccine and half a different vaccine, such as a meningococcal (meningitis and septicemia) vaccine, and then wait until they get exposed to Covid and see how many catch it.

So, let’s say you give 1,000 people the Pfizer vaccine and 1,000 people the meningococcal vaccine. And you wait until 100 cases have been identified of Covid, and then you find that five are in the Pfizer arm, and 95 in those given the meningococcal vaccine, which isn’t going to protect against Covid. Then you can say it’s 95% effective. No vaccine is ever 100% effective, so 95% is very good.

The data from both vaccine trials were presented at press conferences rather than in peer-reviewed papers. How confident can we be that these results are accurate and reliable?
The Medicines and Healthcare products Regulatory Agency (MHRA), our sister body, has a holy triad: it judges safety, quality and efficacy. It won’t be swung by a press conference, and it uses internal and external peer review, just as a scientific journal does.

The government has now accepted the recommendation from the MHRA to approve Pfizer/BioNTech’s Covid-19 vaccine for use. This follows months of rigorous clinical trials and a thorough analysis of the data by experts at the MHRA who have concluded that the vaccine has met its strict standards of safety, quality and effectiveness.

We’ve heard a lot about herd immunity this year. How many people should receive the vaccine before we can expect to achieve herd immunity?
It varies with the vaccine and it varies with the virulence of the virus. Some diseases such as Ebola are very virulent, whereas you could be in contact with people with leprosy (which is not a virus, but it’s a good metaphor) for years and not catch it. For measles, mumps and rubella (MMR), you’re looking at trying to get more than 90% of children vaccinated. Figures for Covid-19 have been incredibly variable. At times it looked as low as 65%, and at others as high as 90%, so maybe the answer to that isn’t known yet.

Do we know when the UK might be in a position to start vaccinating people?
It’s a new vaccine, you’ve got to preserve the chain of supply, you’ve got to have staff trained to give it. The doses have to be manufactured and brought across the Channel and distributed. Some will be done before Christmas, and some in the new year, but to vaccinate 65 million people I think we’re looking into half way through next year.

The NHS has decades of experience in delivering large-scale vaccination programmes and will begin putting their extensive preparations into action to provide care and support to all those eligible for vaccination. The vaccine will be made available across the UK from next week. When it’s your turn, you will receive a notification.

What has been the role of the Health Research Authority in tackling Covid-19?
The HRA is playing an absolutely crucial part in Covid-19 research – not just the vaccine. We’ve looked at 650 studies, for which something like 400,000 people in the UK have been recruited. Nobody can do research on patients unless the HRA approves it first, so we are the absolute gatekeeper.

Our 200 staff have worked really hard during this lockdown – they’ve worked nights and weekends. We need to disabuse the public of the idea that corners are being cut, and that our staff are doing things on the fly and not doing it properly – they’ve absolutely stuck to their job and followed every single procedure.

This advertiser content was paid for by the UK government. All together (Fight Covid-19) is a government-backed initiative tasked with informing the UK about the Covid-19 pandemic. For more information, visit gov.uk/coronavirus