Is the vaccine safe? Do I need it if I've had Covid? Readers' questions answered

‘Zero chance’ mRNA can alter genes, says expert, adding that vaccine can ‘top up’ immune response from infection

Is the new Covid vaccine our way back to normality? - video explainer

How do we know there won’t be long-term side-effects?

“The concerted efforts put into developing a vaccine are wonderful but they can’t possibly know about long-term adverse effects. I’ll have it if it’s offered to me, and at my age long-term effects are irrelevant. I just hope it doesn’t turn out to be a latter-day thalidomide.” Jenny Walters, retired teacher, Ashburton

Vaccines are licensed on the basis of data from clinical trials, which aim to assess their short-term safety, ability to generate an immune response, and their ability to prevent disease in hundreds, and then thousands of volunteers. So far, more than 43,538 people have been enrolled in the Pfizer/BioNTech vaccine trial – approximately half of whom will have received the real vaccine, and the other half a placebo – with the first doses administered in April or May. So far, it appears to be well-tolerated.

It is also important to note that most adverse events occur shortly after receiving a vaccine, rather than after many months or years, said Prof Robin Shattock, the head of mucosal infection and immunity at Imperial College London.

Given that this is a brand-new type of vaccine, it is not impossible that someone could be allergic to a component of it, said Paul Hunter, a professor in medicine at the University of East Anglia. However, this would show up shortly after administration of the vaccine.

Even once a vaccine is licensed, scientists will continue to monitor its safety to identify any rare side-effects that clinical trials may not have detected, eg because they didn’t include people with underlying vulnerabilities. Crucially, health workers are trained to report any adverse event that they, or the parent of a vaccinated child, are concerned about, regardless of whether they think the vaccine triggered it. And they are told to be particularly vigilant in the case of newly introduced vaccines. If an adverse event is reported, the Medicines and Healthcare products Regulatory Agency (MHRA) will carefully investigate whether it is likely to be a coincidence or a result of the vaccine, and intervene where necessary, eg by issuing warnings not to give the vaccine to certain groups, or even withdrawing the vaccine in rare circumstances.

“If you go to 10 million people, you can never rule out that there won’t be someone out there who might respond in a abnormal way,” Shattock said. “I think people have to make a judgment call, because if you have some underlying health condition that nobody predicted, which might give you a worse response to the vaccine, it would probably give you a far worse response to the actual virus.”

Will the vaccine be safe for people with underlying medical conditions?

“I feel very relieved and excited at the prospect of being protected against Covid and life returning to some sort of normality. I also feel some apprehension; how my body might react with heart issues and an autoimmune disorder?” Trudie, Tunbridge Wells

It is likely that people with underlying health conditions will be particularly closely monitored once any vaccine is approved and rolled out. Also, if there’s any reason to suspect that a certain population might be adversely affected by a vaccine, regulators may ask for a substudy to be conducted to assess the safety in this group, before allowing it to be more widely administered to people with this condition.

Quick guide

Who in the UK will get the new Covid-19 vaccine first?

The UK has become the first western country to license a vaccine against Covid. The government’s joint committee on vaccination and immunisation has published a list of groups of people who will be prioritised to receive a vaccine for Covid-19. The list is:

1 All those 80 years of age and over and health and social care workers.

2 All those 75 and over.

3 All those 70 and over.

4 All those 65 and over.

5 Adults under 65 at high at risk of serious disease and mortality from Covid-19.

6 Adults under 65 at moderate risk of at risk of serious disease and mortality from Covid-19.

7 All those 60 and over.

8 All those 55 and over.

9 All those 50 and over.

10 Rest of the population.

How long does the RNA in the vaccine stick around for, and could it damage our cells?

“The vaccine contains messenger RNA, which makes cells produce spike proteins, but does this process get turned off, or go on indefinitely? What are the target cells, and does it damage them?” Anonymous, West Midlands

The Pfizer/BioNTech vaccine uses a piece of genetic code, called messenger RNA (mRNA), to issue instructions to the protein-making machinery in our cells to manufacture viral proteins. The vaccine is injected into the shoulder muscle, so the mRNA will mostly get into muscle cells, but probably also some immune cells. “I think people are concerned when they hear the term ‘genetic material’, but the really good thing about RNA is that it falls apart very quickly – in a cell, it’ll hang around for about 72 hours,” Shattock said. “And it doesn’t get into the nucleus where your chromosomes are, so there’s zero chance that it can change your genes.”

Once manufactured, the viral proteins are displayed on the cells’ surface, where circulating immune cells will detect and raise an immune response against them.

Will this vaccine really enable us to return to normality, and how soon?

“The government only secured enough doses to vaccinate 5 million people – 7.5% of the UK population. Eventually we may get to vaccinating about 30% of the population. This is not enough to get back to normal, because two out of every three people will still be susceptible to Covid-19.” Olga Ucar, medical writer, Manchester

Even with a vaccine, it’s unlikely that society will return to normal overnight. “It is going to be a gradual process, and my estimation is it’s going to take at least until the summer for any degree of normality to return,” said Shattock.

Also, although the government’s full vaccination strategy hasn’t yet been revealed, it is unlikely it will try to vaccinate the entire UK population – at least for the time being. Rather, its strategy may bear more resemblance to what happens with flu vaccination, where elderly people and those with underlying conditions that make them very vulnerable are prioritised. Approximately 10 million people fall into these categories, Shattock said. “As increasing numbers of them are vaccinated, we may find that we can perhaps start to get life back to normal because there will be fewer people having severe disease, fewer people needing to be in intensive care, and because there are fewer of them, those that do end up there will get better-quality care.”

Is there any point in getting vaccinated if you’ve already had Covid?

“I had Covid-19 six weeks ago, so I might be immune, or I might not. I have no idea whether there is any point in getting vaccinated.” Bill Dixon, retired physics teacher, Madrid.

So far, vaccine trials have focused on people who haven’t been exposed to the coronavirus, so the effect of vaccination on people who have been exposed is unclear. However, since immunity to the virus seems to wane over time, it probably would be worth getting vaccinated. “The level of immunity from natural infection is really variable, so some people get a very strong immune response, and some people get quite a weak immune response,” said Shattock. “The vaccine would top up your immune response, and hopefully provide protection for longer.”

Even once people have been vaccinated, it is possible that they will require additional booster doses to keep their immunity topped up.

Where is the infrastructure needed to transport and store it at the right temperature?

“When I worked in general practice we had a problem with the storage of conventional vaccines, which need to be kept refrigerated or they are inactivated and useless. The new vaccine needs to be kept below -70C. How many doses will be wasted because we are not ready to handle them?” Gavin, Bristol

Transporting, storing and administering this vaccine won’t be easy, but the infrastructure is being put in place. Pfizer is reported to have designed suitcase-sized shipping containers, capable of holding 1,000-5,000 doses at the required temperature for up to ten days, while they’re transported to local or regional storage facilities, eg at hospitals. From there, they are likely to be shuttled to GP surgeries for immediate use – the vaccine remains viable for approximately 24 hours after it comes out of the freezer. Rather than having a single surgery delivering a few vaccines per day, it is likely that groups of surgeries will pool their resources and have one centre doing large numbers of vaccinations over a very intense period, Shattock said.

Also, don’t forget that many other vaccines are being developed, which won’t require ultra-cold storage, so we’re unlikely to be solely reliant on the Pfizer vaccine (assuming it is approved).

This article was amended on 15 November 2020. An earlier version said the Pfizer/BioNTech vaccine had been administered to more than 43,538 people, but this was the number of people enrolled in the trial, only around half of whom have received the real vaccine.