The road to immunity: the end is in sight, but several obstacles still need to be overcome

In the most encouraging development since dexamethasone was found to slash mortality rates in seriously ill coronavirus patients, interim results from a large-scale Pfizer/BioNTech trial have shown that its candidate vaccine is 90% effective.

This is more than many in the scientific community were daring to hope for. An efficacy rate of 60%, similar to the flu vaccine, was thought of as being a reasonable best case scenario.

The WHO has previously said that it didn’t expect any vaccine to be widely disseminated until mid-2021 at the earliest. If the trial results are accurate and the vaccine is deemed safe, we could see it rolled out much sooner.

The companies say that 50 million doses could be produced by the end of 2020 and 1.3 billion by the end of 2021. The UK government has ordered 40 million doses, and has said that 10 million of these could be available by the end of the year if regulators approve the vaccine.

If the Pfizer/BioNTech vaccine, labelled BNT162b2, lives up to its promise its development will have been a monumental achievement. It usually takes around ten years to develop a vaccine for mass use. The two firms have taken just a few months.

So what now?

The first step is getting the vaccine approved by the relevant authorities. The trial will continue until 164 infections have been reported which will give regulators a clearer picture of the vaccine’s efficacy. The team is also waiting until the third week of November when it will have gathered two months’ worth of safety data. Pfizer will then apply for emergency licensing so the vaccine can be given to the general public outside trials. Regulators could give BNT162b2 the green light for use in at-risk groups by the end of the year and broader approval might come in the first quarter of 2021.

Even after a vaccine is shown to be both safe and effective, obstacles to mass immunisation will remain. “Then it becomes a manufacturing and logistical issue,” British venture capitalist, Jon Moulton, who has donated several million pounds to Covid-19 research projects, told Reaction. “This is not one of the easiest vaccines to make.”

It is believed that the vaccine must be kept at minus 70 Celsius right up until the dose is injected in a patient’s arm, a far lower temperature than most medicines require because the shots contain fragile genetic material.

A method for producing the vaccine on a large scale is yet to be developed and the cold-chain requirement will make both manufacture and worldwide distribution much more difficult as ultra-cold freezers are mostly restricted to research labs.

But once the vaccine starts to be produced in high quantities and shipped across the world, administering it will be the next step. The government has proposed amendments to human medicine regulations that would allow non-registered healthcare professionals, such as pharmacists, to also administer the vaccine which requires two shots per person.

Discussions involving the police and army to set up mass vaccination centres across the country – which could involve using existing Nightingale facilities – are already underway.

Once infrastructure is in place, the most important question will be who gets the new vaccine first. The Joint Committee on Vaccination and Immunisation has published a pecking order of priority groups.

At the top are care home residents and staff, followed by the over 80s and front-line health workers. Priority then descends according to age. There are notable omissions. There is no mention, for instance, of high-risk children in the priority hierarchy, only adults. The committee has stressed, however, that this order isn’t definitive.

In last night’s press conference, Jonathan Van-Tam, deputy Chief Medical Officer, described the trial results as “a really very important scientific breakthrough.” Boris Johnson struck a more cautious note, insisting that “we cannot use this news as a solution.”

Professor Hugh Pennington, professor of bacteriology at the University of Aberdeen, echoed the Prime Minister’s sentiment, telling Reaction that it would be wrong to think of a vaccine – whether Pfizer’s or any other – as the silver bullet we’ve been hoping for. “A vaccine will be very useful. It will protect some of the people who are most seriously at risk of dying from the virus, so it will reduce pressure on the NHS.

“But it won’t see the virus off. We’ll still need stringent contact tracing and self-isolation of people who have a positive result or close contact. It’s a combination of the two.”

Many questions remain unanswered, such as how long immunity will last and whether the vaccine prevents infectiousness (it’s possible that the jab could prevent someone from developing symptoms but not from spreading the virus themselves). “There are bound to be loads of unknowns,” says Moulton. “All kinds of things could go wrong. Nobody’s done any long term testing. It seems extremely remote but it is conceivable there are long term effects.

“It is also conceivable that the virus will evolve away from a version that this vaccine works for – the obvious example being the mink strain coming out of Denmark at the moment, which is a tiny bit different. But is it enough to make the vaccine ineffective? We haven’t a clue.”

Having ten million shots in the UK by Christmas seems unlikely, but Moulton remains optimistic. “[Pfizer] is talking about having a few million – maybe two million – vaccines available by the end of the year,” he says. “It’s likely that most of those would go to the US. Some will come to the UK. We might have one, two or three hundred thousand injections in the UK by the new year, which will still be a great benefit.”

Crucially, the Pfizer/BioNTech breakthrough has increased the probability that other vaccines being developed will also be successful. The government has hedged its bets, pre-ordering 340 million doses of different Covid-19 vaccinations – the highest number per capita of any country – from a total of six manufacturers. Trials are continuing on other vaccines including the former frontrunner being developed by Oxford University and AstraZeneca, of which 100 million doses have been pre-ordered. News is expected in the coming weeks.

For the first time in many months, the future is looking much brighter.