Pfizer vaccine: How does it work and how effective is it?

Amid the doom and gloom of 2020, this feels like the first tentative step towards the light at the end of the tunnel

The vaccine candidate put forward by Pfizer and its German partner BioNTech has been approved by UK regulator MHRNA, making it the first country to have a clinically authorised vaccine to roll out in the coming weeks and months.

The news has been heralded as “fantastic” by ministers, with health secretary  Matt Hancock saying: “Help is on it’s way.” 

The Pfizer vaccine candidate was the first to mark a major milestone in the fight against Covid-19 when it was shown to be highly efficacious. According to early data analysis, it is 95 per cent effective at preventing disease, while no serious safety concerns have been observed.

The Medicines and Healthcare products Regulatory Agency (MHRA) approved the jab after “months of rigorous clinical trials and a thorough analysis of the data by experts”, said a spokesperson for the Department of Health and Social Care on Wednesday.

There is much optimism surrounding the breakthrough, and more than just a glimmer of hope that life could could return to normal from next Easter onwards.

So, what do we know about the vaccine?

The Pfizer/BioNTech vaccine has been shown in studies to be 95 per cent effective and works in all age groups. More than 43,000 participants took part in the clinical trials for the vaccine, which was well-tolerated across all populations, according to the company’s data, and no serious safety concerns were observed.

The vaccine will be administered in two doses, within 21 days of one another. According to Pfizer, final analysis indicates that a 30g dosage induced a “high rate of protection against Covid-19” only 29 days after the first dose.

The second dose is a booster, and it will take a few weeks for immunity to build.

It is manufactured in Belgium and must be stored at around -70C, and will be transported in specialised temperature-controlled boxes packed with dry ice, which can be used as temporary units for 15 days if refilled with dry ice.

Lastly, we know that the vaccine is safe. Pfizer and BioNTech have reported that no serious safety concerns or adverse reactions have been noted.

What don’t we know?

How long immunity lasts for. It remains unclear at what point the immune response triggered by the vaccine will fade away. Six months? Eight months? A year, perhaps? Many experts have predicted that it’s likely booster jabs will need to be administered, especially among the elderly who are known to have weaker immune systems.

We don’t know what sort of immunological activity it generates in different demographic groups. Scientists and governments will be particularly keen to see the vaccine’s effectiveness among those aged 60 and above.

According to Pfizer, their vaccine is 94 per cent effective in people aged 65 and over.

Similarly, experts have said the full effect of a vaccine on transmission in the population will not be known until one is in circulation and more data is collected.

What comes next?

In the UK, where the vaccine is now approved, the vaccination programme could be rolled out as early as next week. The UK has ordered 40 million doses, enough to vaccinate 20 million people with two doses, given 21 days apart.

Around 10 million doses are expected to be available for use in the UK in the coming weeks for priority groups. This includes healthcare workers, vulnerable and elderly people. 800,000 doses are expected to arrive next week.

A list of who will receive the vaccine first will be set out later on Wednesday.

Can we expect challenges in the global rollout?

Absolutely. The Pfizer vaccine uses mRNA technology, which involves injecting genetic coding into humans to replicate the ‘spike’ protein seen on Sars-Cov-2, thereby triggering the immune response. However, this type of vaccine is highly unstable and needs to be stored at -70C. This makes the transportation and storage of doses difficult and expensive.

“This could create major logistical challenges for mass treatment outside major urban areas and in low or middle income countries,” said Andrew Hill, a senior visiting research fellow in the department of pharmacology at the University of Liverpool.

When we expect life in the UK to return to normal?

According to professor Sir John Bell, a member of the government’s Scientific Advisory Group for Emergencies, life in the UK could start returning to some degree of normality by spring next year.

“I’m probably the first guy to say that but I will say that with some confidence,” said Sir John, who is regius professor of medicine at Oxford University.

Mr Hancock told BBC Breakfast: "2020 has been just awful and 2021 is going to be better, and help is on its way with this vaccine.

“I’m confident now with the news today that from spring, from Easter onwards, things are going to be better and we’re going to have a summer next year that everybody can enjoy.”

Peter Horby, professor of emerging infectious diseases at Oxford university, said “there is a long, long way to go before vaccines will start to make a real difference”. 

Should the Oxford University vaccine also prove effective, the UK will have access to a further 60 million doses – but these too will take time to be manufactured and rolled out. 

What are the advantages of the technology used by the Pfizer vaccine?

No actual virus is needed to create an mRNA vaccine. This means the rate at which the vaccine can be produced is dramatically accelerated. As a result, mRNA vaccines have been hailed as potentially offering a rapid solution to new outbreaks of infectious diseases.

In theory, they can also be modified reasonably quickly if, for example, a virus develops mutations and begins to change.

mRNA vaccines are also cheaper to produce than traditional vaccines. But both will play an important role in tackling Covid-19.

Any other good news?

Yes. There are a number of other vaccines in development that use the same mRNA technology as Pfizer, including the Moderna candidate. Moderna announced its primary efficacy analysis of its Covid vaccine clinical study on 30 November, which found that vaccine efficacy was 94.1 per cent against Covid-19 and 100 per cent against severe Covid-19.

The company filed with the US Food and Drug Administration (FDA) for emergency use authorisation and requested conditional approval from the European Medicines Agency (EMA).

Experts are confident there will be more than one vaccine capable of generating an immune response.

Richard Hatchett, chief executive of the Coalition for Epidemic Preparedness Innovations, said: “We believe these interim results also increase the probability of success of other Covid-19 candidate vaccines which use a similar approach.”

Sir Bell said: “It rolls the pitch for other vaccines because I can't see any reason now why we shouldn't have a handful of good vaccines.”