Covid-19 vaccines: Everything you need to know

Samuel Lovett
·13-min read
<p>Experts have estimated that vaccine coverage will be needed among 60-70 per cent of a country’s population to achieve herd immunity</p> (AFP/Getty)

Experts have estimated that vaccine coverage will be needed among 60-70 per cent of a country’s population to achieve herd immunity

(AFP/Getty)

After nine months in which the entire world has been paralysed by coronavirus, a way out is finally in sight through the Covid-19 vaccines. The past few weeks have brought positive news of candidates from Pfizer, Moderna and Oxford University with AstraZeneca. But with these developments has come a rise in anti-vaxxers, promoting conspiracy theories and unwarranted safety fears.

So what are the facts? Here’s information you can trust, telling you everything you need to know about how the vaccines work, how they’ve been tested and what comes next.

When can we expect to get a vaccine?

Possibly the biggest question of them all. In the UK, supplies of the two-dose Pfizer vaccine will be made available for administration after the Medicines and Healthcare products Regulatory Agency (MHRA) approved the candidate for use on Wednesday. A total of 800,000 doses – enough to vaccinate 400,000 Britons – are set to be distributed across the country from 7 December.

Initially, up to 10 million doses were expected to be delivered to the UK before the end of the year, though health secretary Matt Hancock has refused to commit to a definitive number. Sean Marrett, BioNTech’s chief business officer, has said it is likely the UK will receive five million doses this year.

The MHRA is also conducting rolling reviews of the Moderna and Oxford candidates, with a final decision set to be made on these two vaccines in the coming weeks.

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“I’m hopeful… but not yet certain that we could begin to see some vaccine by Christmas,” Professor Jonathan Van-Tam, England’s deputy chief medical officer, said earlier this month.

The World Health Organisation, No 10 and other governments have made it clear that the most vulnerable will be prioritised, including the elderly, people with underlying health conditions, and healthcare workers.

“I wouldn’t be surprised if we hit the new year with two or three vaccines, all of which could be distributed,” Sir John Bell, a member of the government’s Scientific Advisory Group for Emergencies (Sage), said last week.

“That's why I’m quite optimistic of getting enough vaccinations done in the first quarter of next year that by spring things will start to look much more normal than they do now.”

What do we know about the vaccines so far?

There are three main candidates that have shown promising results – from Pfizer and BioNTech, Moderna, and Oxford University’s partnership with AstraZeneca.

Pfizer and Moderna are developing mRNA vaccines, a new technique that was being used to look at cancer vaccines pre-coronavirus.

It introduces a genetic sequence – messenger ribonucleic acid (mRNA) – in to the body, which instructs cells to produce the Sars-CoV-2 spike protein, which is known as an “antigen”. The immune system then springs into action to fight off what it perceives to be a foreign invader. The process leaves behind a protective memory that enables the body to tackle the real infection.

Final analysis of the two-dose Pfizer/BioNTech vaccine has shown it is safe and 95 per cent effective in preventing Covid-19, paving the way for its imminent authorisation and global distribution. The candidate has passed its full safety checks, Pfizer said, and is now ready to be presented to regulatory authorities for market approval. BioNTech is “very confident” the jab will reduce transmission of the disease, perhaps by 50 per cent – though long-term analysis is required to establish this.

Moderna announced that its two-dose vaccine is 94.5 per cent effective in preventing disease. There are also promising signs that it can protect the over-65 age group and that it stops severe disease.

The Oxford/AstraZeneca vaccine uses an adenoviral vector, which had been used to develop a vaccine for Middle East respiratory syndrome (Mers) – another member of the coronavirus family. It uses a genetically engineered chimpanzee adenovirus – which causes the common flu in apes – to carry the DNA for the Sars-CoV-2 spike protein into human cells. It becomes part of the host cell, triggering an immune response similar to the one described above.

Trial results show that the vaccine is 90 per cent effective in preventing disease if administered at a half dose and then at a full dose, or 62 per cent effective if administered in two full doses. Professor Andrew Pollard, chief investigator of the Oxford Vaccine Trial group, said it will take a “little bit longer” to have robust data on the vaccine's effectiveness in older adults. However, he said not enough time had passed to know whether people were still protected a year after being vaccinated.

Are the vaccines safe?

Vaccines and drugs often take years to go through trials and development before gaining approval and being used to treat patients. So with vaccines ready to be delivered within months of Covid-19’s emergence, it’s fair to ask how we can be sure they’re safe.

Sarah Gilbert, the professor of vaccinology behind the Oxford vaccine, insists that no corners have been cut and says that, if her candidate is approved, it will have gone through all the necessary checks and balances.

“We’ve been able to find ways to save time when going through all the normal processes,” she told The Independent. “We’ve worked with the regulators and ethical committee to minimise the time it takes to get to approval, but the approval is still the full approval – it’s not missing anything.”

She pointed to “accelerated procedures” that have helped to cut away unnecessary waiting time. “Normally we can’t mention the trial and ask anyone to consider taking part until it’s all completely approved,” she said. “This time we were allowed to advertise the trials and contact people.”

Individuals who expressed an interest were then vetted and prepared for vaccination, which only followed once approval was secured. “So we had a cohort of people ready to vaccinate. That doesn’t normally happen.”

Regulatory bodies have similarly increased the speed at which they work. Rolling reviews were introduced to assess clinical trial data as it became available. This allowed bodies such as the MHRA to put together a picture of the vaccines’ effectiveness and safety as the results came in.

From the frontline

Dr Mark Toshner, a clinical doctor involved in running and recruiting volunteers for the Oxford trials, explains that much of the spent developing vaccines concerns jumping through bureaucratic hoops.

“I’ve seen a lot of people quote this 10 years it takes for drug and vaccine development,” he told the BBC this week. “I wanted to explain what happens in those 10 years: most of the time it’s a lot of nothing.

“During the course of those 10 years I’ll be spending significant proportions of it writing grants, having grants rejected, rewriting them, resubmitting them. That can take two to three years in itself.

“Then when you’re actually lucky enough to get a grant, you have to go through a very extensive regulatory process that normally takes months and you have contract negotiations. They can sometimes take years.”

He said that the urgency to develop a vaccine has done away with much of these delays and accelerated the various moving parts of the production process.

“Somebody described it as trying to get through London in rush hour. Imagine what that would be like if somebody cleared all the traffic, turned on the traffic lights from red to green and then you got a police escort all the way.”

Steve Bates, CEO of the UK BioIndustry Association, said the usual processes involved in getting a vaccine to market have been done “concurrently rather than sequentially”.

“By doing things at the same time – the discovery work, the manufacturing scale-up, the clinical trials done at pace, rolling reviews from the regulators, thinking about distribution and engagement with health systems – this shows there is the potential to transform these pathways,” he told The Independent.

Could issues present themselves years down the line? Professor Robin Shattock, who is leading development of the Imperial College London vaccine, says most adverse reactions occur shortly after receiving a vaccine – rather than in the months or years to follow.

Paul Hunter, a professor in medicine at the University of East Anglia, acknowledges that there could be components to the mRNA platforms which – as new technology – might induce an allergic response, but adds that this would have been picked up in the immediate aftermath of vaccination.

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. If these adverse events do occur, the rollout of the vaccine in question will be paused pending an investigation.

As is the case with all health care products and medicines, 100 per cent safety can never be guaranteed. From the very rare allergic reactions that can arise from taking paracetamol to the low-risk, short-term side-effects that come with having an X-ray, there are always considerations to be held in mind.

The same logic applies to these Covid-19 vaccines. Both the Moderna and Pfizer jabs have been shown to be safe, and further independent assessment will confirm this. For those who believe in the power and integrity of modern science, there is no reason to dispute such outcomes.

One very real danger comes from vaccine hesitancy. A Pew Research poll conducted in September found about half of US adults intended not to take a vaccine. In the UK, one in six of people surveyed for a King’s College London poll said they’d be unlikely to take a jab.

If too few people choose to be inoculated, the vaccines will not be able to lower the level of risk for the population at large. Experts have estimated that vaccine coverage will be needed among 60-70 per cent of a country’s population to achieve herd immunity – though the complexities of distribution will likely hinder or slow attempts to achieve widespread vaccination.

How will it be distributed?

Pfizer said it expects to supply globally up to 50 million vaccine doses in 2020 and up to 1.3 billion doses in 2021. Moderna anticipates it will produced between 500 million and 1 billion doses next year, while AstraZeneca – which has been licensed to manufacture the Oxford vaccine – has laid out plans to deliver 3 billion doses over the next 13 months.

But this will be no easy feat. “Volume is going to be a serious issue,” Dr Mohga Kamal-Yanni, a consultant in global health and access to medicines, told The Independent.

Bill Gates took measures into his own hands earlier in the pandemic, pumping money into the construction of production plants for seven promising vaccine candidates. If they don’t work, Mr Gates stands to lose billions. “It is worth it,” he said in April.

Doses and supply

Now that three vaccines have been shown to work, how many doses can the UK expect to receive by the end of the year?

Pfizer/BioNTech: Sean Marrett, chief business officer, has said it is likely the UK will receive five million doses this year. This will allow 2.5 million Britons across the four nations to get vaccinated. A further 35 million doses will follow after that.

Moderna: The American biotech is in the process of scaling up its manufacturing supply chain in Europe. This means it’s unlikely the UK’s allocated five million doses will arrive before spring of next year.

Oxford University/AstraZeneca: Four million doses are ready to go in the UK. They’ll be dispatched and administered once approval is granted by the regulators. In total, the government has pre-ordered 100 million shots – enough to vaccinate 50 million Britons – which will be delivered throughout 2021. AstraZeneca said 40 million doses will be ready by the end of March next year.

Some pharmaceuticals have passed their intellectual property to other manufacturers, like the Serum of Institute of India, to help produce supplies in different parts of the world. The Indian company is committed to producing doses of the AstraZeneca vaccine at low costs – roughly $3 per shot – to ensure they can be accessed in low- and middle-income countries in the global south.

The transportation and storage of doses – the so-called “cold chain” – is another hurdle that must be overcome. Some of the mRNA vaccines, such as the Pfizer jab, will be needed to be stored at temperatures as low as -70C to maintain the integrity of the genetic material within the doses.

But many of the world’s poorer nations do not have the technology and facilities to meet this requirement, meaning they will be unable to roll out supplies on the same scale as their richer counterparts.

Toby Peters, a professor of energy storage and cold economy at the University of Birmingham, said little attention had been given to the difficulties involved in rapid worldwide distribution.

“The new two-shot vaccine from Pfizer has to be maintained at -80C – nowhere on the planet does the logistical capacity exist to distribute vaccines at this temperature and volume without massive investment,” he told The Independent.

Prof Shattock said that candidates such as Pfizer’s may never reach some low- and middle-income nations.

“Technologies that require very low temperature cold chains and are very expensive by all accounts, we may not see in these countries,” he said.

“The challenges in lower and middle incomes is that a lot of the populations aren’t in an urban setting. You imagine it’s going to be a logistical problem to get a vaccine to all the vulnerable population in the UK. But if you’re in a South American country and you’ve got people living up in the Andes or very rural communities, it presents so much bigger challenges.”

Not all vaccines are facing these issues, though. Some, like the Oxford candidate, can be stored at fridge temperature (2C-8C), meaning they’ll be more accessible for the global market.

Moderna has said its mRNA vaccine can be stored at fridge temperature for 30 days, or -20C for up to six months.

Taking into account the huge number of doses that AstraZeneca has committed to producing by the end of next year, along with the low cost of shots (roughly £2.26 per dose, compared to the Pfizer jab which is expected to cost £24.06), Prof Gilbert is confident her vaccine could be the leading candidate to turn the tide against Covid-19.

“I think it probably is,” she said. “The very large number of doses and the global distribution are both very important components to that. Some of the manufacturers will not produce as many doses, so will therefore have limited impact.

“I think it takes us a lot closer to being able to end this pandemic by vaccination.”

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