UK regulators have approved an emergency Covid-19 vaccine developed by Pfizer and its partner BioNTech, so the vaccine is expected to launch soon. Here we answer questions about the science of the vaccine, who will get it first, how safe we can be in the approval process, and how logistical it is to vaccinate everyone in the UK.
How effective is the vaccine?
Over 95 percent. The Phase 3 trials of the Pfizer / BioNTech vaccine enrolled 42,000 people, approximately half of whom received the experimental vaccine and the remainder a placebo. A total of 170 people fell ill with Covid-19. Only eight of them were in the vaccine group; 162 had received the placebo. Around 5 percent of the cases were in the vaccine group, where the 95 percent figure comes from. That is a very healthy number: the World Health Organization (WHO) has announced that it is satisfied with 50 percent.
What’s in the vaccine?
The active substance is messenger RNA, which contains instructions on how to make the virus’ spike protein, which it uses to gain access to cells. The mRNA is synthetic and is not extracted from actual viruses. It is delivered in a tiny ball of inert fatty material called lipid nanoparticles.
The RNA-carrying nanoparticles are suspended in saline and injected into muscle tissue in the upper arm. The mRNA is then taken up by specialized immune cells, which follow their instructions to make the spike protein, just as they would if they were infected with the actual virus.
The spike protein is recognized as foreign by the immune system, which triggers an attack against it. Antibodies, B cells and T cells are activated, says Uğur Şahin, the managing director of the small German company BioNTech, which developed the vaccine together with the US drug giant Pfizer. An immune memory is also established, meaning that the immune system has learned to defeat the pathogen and is prepared to have a quick response if it encounters the coronavirus again.
How long does the immune memory last?
It’s hard to tell right now as the clinical trials weren’t designed to answer that question and in any case didn’t start firing second shots until 4 months ago. WHO says it will take 6 months. Over time it will become clearer and the volunteers will continue to be monitored. Sahin expects the protection to last “months or even years”. Given what we know about natural immunity that looks about right, says Eleanor Riley of the University of Edinburgh in the UK. She envisions that in the worst case scenario, people need annual boosters.
How long does it take for immunity to fully develop after vaccination?
The study began assessing immunity 7 days after the second shot. We know that protective immunity builds within four weeks of the first dose, but Sahin says it seems to develop earlier. More details will be released in a few days, he says.
What happens to the mRNA in the body?
It is active for a few days and then quickly breaks down.
It is a two-shot vaccine. So what happens when people miss their second shot? Does a single shot still protect?
Two shots are required and the second shot is required to achieve immunity. The interval between doses in the study ranged from 19 to 42 days. Only 2 percent of the subjects missed their second dose, so it’s not entirely clear what happens under these circumstances.
Are there any side effects?
Sometimes, but they’re mild. In the study, the vaccine was generally well tolerated and an independent data monitoring committee reported no serious safety concerns. The worst side effects were fatigue and headache after the second dose. About 4 percent of people reported tiredness and 2 percent reported headaches. Other side effects included injection site pain and muscle pain. These are “common reactions you would have if you were vaccinated,” says Özlem Türeci of BioNTech. Older adults reported fewer and milder side effects.
Does it work in the elderly?
Yes. The study participants were up to 85 years old, and the effectiveness in people over 65 was 94 percent – a tiny bit lower than the total but still very protective and much higher than some vaccine experts feared. The vaccine has not been tested in people over the age of 85.
What about other vulnerable groups?
The vaccine appears to be equally effective regardless of the age, gender, and ethnicity of the recipient. It has been tested extensively in people who have already had the virus and are not experiencing any ill effects. It has also been tested in people with “stable” pre-existing conditions – also known as comorbidities – including diabetes, cancer, hepatitis B, hepatitis C, and well-treated HIV. Her answer was as good as anyone else’s.
It has not been tested in people with serious or worsening comorbidities, but they will still be eligible for the vaccine. BioNTech says it has data on this group and will publish it in a few days.
Does it protect everyone?
No. In the studies, of approximately 20,000 people given the vaccine, eight were caught with Covid-19 and one became seriously ill. In contrast, 164 people who received the placebo, nine became seriously ill. It is not known why some people did not respond to the vaccine. However, a 95 percent success rate is about as good as any vaccine.
Does it prevent people from catching and transmitting the virus?
We still don’t know. The study was designed to test for symptomatic Covid-19 and confirm infection with the virus. Assessing whether the vaccine prevents transmission – which is likely a prerequisite for achieving herd immunity induced by the vaccine – is much more difficult to assess scientifically. However, Pfizer says it is doing more research on this important issue and will be releasing information soon.
Paradoxically, some vaccines can make a disease worse through a process called antibody-enhanced disease. Is that a risk?
Yes, in theory. But it has not been seen with this or any other vaccine against Covid-19 and has not occurred naturally, as is sometimes the case with other viruses.
Have the full data of the study already been published?
No, it doesn’t, but there’s nothing scary about it. Businesses can get news to market instantly, which is much faster than creating a scientific manuscript. Pfizer says every detail of the science will be presented to a high-level, peer-reviewed journal once it’s ready. It is then up to the magazine how long it takes to publish.
Eligibility to participate
Who is first in the queue?
When a vaccine is approved, it is common for people who participated in the clinical trial but received the placebo to be given initial dibs. However, since the study was not conducted in the UK, there is no one in this category.
Nursing home residents and their carers have the highest priority under a priority system developed by the UK Joint Committee on Vaccination and Immunization. Next up are people over 80 and health care workers on the front lines, followed by people over 75, then people in increasingly younger age groups and / or with underlying health problems.
Will someone be excluded from the vaccination program?
Yes. Pregnant women and children under the age of 16 are at least initially not eligible. The vaccine has not been tested in pregnant women or children under the age of 12, and insufficient data are available in children aged 12 to 15 years. However, studies in these groups are not yet completed or planned.
Anyone else can get it?
Yes, but most of them have to wait for their turn. BioNTech’s Sean Marett says the exact delivery schedule will depend on how quickly factories can produce it and where else the vaccine is approved, as the company is committed to fair access. “We will be dispensing as many cans as possible as quickly as possible,” he says.
What does “Temporary Emergency Authorization” mean?
Exactly what it says on the tin. The UK Medicines and Health Products Regulatory Authority (MHRA) has accelerated the approval process in recognition of a public health emergency and could just as quickly revoke approval. However, this is highly unlikely as it has made a thorough assessment of the safety and efficacy data and has seen nothing to give rise to non-approval.
Will the vaccine inevitably move from temporary to full approval?
Probably, but it’s not a given. Pfizer expects this to happen, but it’s in the hands of regulators.
It all happened very quickly. Can we be sure that no corners have been cut?
Yes. The MHRA is an independent body, as is the Commission for Medicinal Products for Human Use (CHM), which was also involved in the decision on the approval of the vaccine. Although the MHRA only received full clinical trial data a little over a week ago, vaccine developers have been providing information that has been subject to ongoing review since October.
The European Medicines Agency, the medicines agency that approves Covid-19 vaccines for the European Union, said in a statement that their process to ensure the safety and effectiveness of the vaccine is based on more evidence and controls than those used in the EU UNITED KINGDOM emergency permit.
According to the vaccine developers, the MHRA requested exactly the same amount of information as any other regulatory agency. It worked around the clock to evaluate it, says Türeci.
Are other countries likely to approve the vaccine soon?
Yes. Pfizer / BioNTech have also filed for regulatory approvals in the US, EU, Australia, Canada, Japan and New Zealand and are preparing to file applications with other regulatory agencies around the world. Decisions from the US and the EU are expected this month.
How many cans is the UK getting?
In total, the UK government has pre-ordered 40 million single doses, which is enough for 18 million people who believe that double dosing is around 10 percent wasted. But not all 40 million will come at once. The complete order will be delivered in batches over the course of 2020 and 2021.
When is the vaccine coming to the UK?
The first batch is currently being packaged at Pfizer’s vaccine factory in Puurs, Belgium and will be shipped to the UK by truck and plane as soon as it is ready – possibly as soon as next weekend. UK Health Secretary Matt Hancock said he expected the UK to receive 800,000 doses in the next few days.
When does the vaccination start?
Again as soon as possible.
Doesn’t the vaccine require complicated cold storage?
Yes and no. For long-term storage – i.e. around 6 months – the vaccine must be kept at -70 ° C, which requires special refrigeration equipment. However, Pfizer has invented a dispensing container that will keep the vaccine at this temperature for 10 days, unopened. These containers can also be used for temporary storage in a vaccination facility for up to 30 days, provided that they are filled with dry ice every 5 days. Once thawed, the vaccine can be stored in a normal refrigerator at 2 ° C to 8 ° C for up to five days.
Could the UK formally leave the EU on January 1st, could the supply chain be disrupted?
Possibly. But according to Marett “we will find a different route in the event of a malfunction”.
Where are people vaccinated?
The usual places: general practitioners’ offices, health centers, and hospitals. People are invited by the NHS. The entire supply goes to the NHS and, according to Pfizer, no one can skip the line by buying one.
Could something else go wrong?
Yes, but it is highly unlikely. The effectiveness of vaccines in the real world is almost always less than effectiveness in studies, but the drop would have to be spectacular to fall below the 50 percent threshold accepted by the WHO.
There could be serious adverse effects in the future too, especially since mRNA vaccines are a new technology and have never been widely adopted.
Clinical vaccine studies are not large or long enough to rule out rare but serious side effects that sometimes occur months or even years after vaccination. Individuals who have been vaccinated are monitored for 2 years to make sure there are no serious adverse effects on the wings.
However, these are small theoretical risks. As Fiona Watt of the UK Medical Research Council (MRC) said, “This is great news.”
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