The Oxford/AstraZeneca vaccine is the mainstay of the UK government’s immunisation plans and vital globally.
Will it work against the variant of the virus that emerged in South Africa?
A study carried out by Oxford and Astra Zeneca together with the University of Witwatersrand in South Africa shows that it does not protect people infected with the variant against mild to moderate Covid, but the researchers believe it will still prevent severe illness, hospitalisation and death.
The study involved more than 2,000 people with an average age of 31, which means they were relatively young and at lower risk. So scientists cannot yet be certain the protection remains against serious disease, but they think it’s likely.
Do other vaccines offer better protection against this variant?
It’s not possible to make comparisons because we don’t have the detailed data – the study will be published in the coming days. But trials of other vaccines in communities affected by this variant show that none of them work as well as they do against the original coronavirus.
Quick guide Vaccines: how effective is each one and how many has the UK ordered?
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Pfizer/BioNTech
Country US/Germany
Efficacy 95% a week after the second shot. Pfizer says it is only 52% after the first dose but the UK’s Joint Committee on Vaccination and Immunisation (JCVI) says this may rise to 90% after 21 days.
The UK has ordered 40m doses and is rolling them out now
Doses Clinical trials involved two doses 21 days apart. The UK is stretching this to 12 weeks.
Oxford/AstraZeneca
Country UK
Efficacy 70.4% 14 days after receiving the second dose. May have up to 90% efficacy when given as a half dose followed by a full dose. No severe disease or hospitalisations in anyone who received the vaccine.
The UK has ordered 100m doses and has begun distribution
Doses Two, four to 12 weeks apart
Moderna
Country US
Efficacy Phase 3 trial results suggest an rating of 94.1%.
The UK has ordered 17m doses, to be delivered in March or April
Doses Two, 28 days apart
Novavax
Country US
Efficacy Phase 3 trials suggest 89.3%.
60m doses ordered by the UK, with distribution expected principally in the second half of the year
Doses Two
Janssen (part of Johnson & Johnson)
Country US
Efficacy 72% in preventing mild to moderate cases in US trials but 66% efficacy observed in international trials. 85% efficacy against severe illness, and 100% protection against hospitalisation and death.
30m doses ordered by the UK
Doses: One, making it unique among Covid vaccines with phase 3 results so far
Photograph: Stéphane Mahé/X02520
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Data that has recently been published, from trials of two vaccines that took place partly in South Africa after the emergence of the variant, show a marked decline in efficacy. Novavax had 89% efficacy in trials in the UK, but 60% in South Africa, where 92% of the cases were caused by the variant. The Janssen vaccine, made by a subsidiary of Johnson & Johnson, had 72% efficacy in the US but 57% in South Africa. Both vaccines, however, still protected against severe disease, hospitalisation and death.
Pfizer/BioNTech and Moderna, which ran large-scale trials with spectacular results showing 95% efficacy before the variants appeared, now think the South Africa variant will reduce that. They have only conducted lab studies, but on the basis of those, they say the vaccine may may perform less well against the variant. We don’t yet know how much less well.
What about the variant that emerged in Kent?
There’s better news about this one. Oxford/AstraZeneca have carried out a small study, details of which came out on Friday, with much more upbeat results. In a pre-print, not yet peer-reviewed, they said the vaccine efficacy fell from an average of 84% against the original virus to 75% against the Kent variant.
Researchers from the Cambridge Institute of Therapeutic Immunology & Infectious Disease, led by Prof Ravi Gupta, found that the Pfizer/BioNTech vaccine successfully protected against the Kent variant, called B117. “Our findings suggest that the Pfizer/BioNTech vaccine is likely to offer similar protection against B117 as it does against the previous strain of Sars-CoV-2,” he said.
“Although we found a reduction in the ability of antibodies to neutralise the virus, given the number of antibodies produced following vaccination, this should still only have a relatively modest effect and people should still be protected.”
People over 80 needed a second dose three weeks later, however, to mount an adequate antibody response.
What does this mean for hopes of herd immunity?
Researchers now say there needs to be a shift in thinking. There hasn’t been good data on whether any of the vaccines prevent transmission from one person to another, but governments and the public have of course been hoping that vaccination would deliver herd immunity – so that even people who have not had the jab would be safe – and get life back to normal.
Prof Shabir Madhi from the University of the Witwatersrand, who was the lead investigator in this and other vaccine studies in South Africa, says we need to reset the goal to protecting people from hospital and death and stop assuming the virus will go away.
“These findings recalibrate thinking about how to approach the pandemic virus and shift the focus from the goal of herd immunity against transmission to the protection of all at risk individuals in population against severe disease,” he said.
Can the vaccines be altered to protect us against the variants?
Yes, scientists say. Work is already underway in all the labs. It should not be too difficult to tweak the vaccines to recognise the changed spike protein, but there are challenges. One is testing the variant vaccine, which will not take anything like as long as the original trials. It could be just weeks. Prof Sarah Gilbert, from the University of Oxford, said they were working on it and she expected a new version would be ready in the autumn, when it could be used as a booster dose.
The other challenge is keeping up with the pace of mutations. These variants have emerged swiftly and show quite a number of changes, and there will be others.
What does the future look like?
Nobody thinks the virus is going away, having spread as widely as it has. It is now endemic in the population. We will probably have to deal with it as we do with the ever-changing flu viruses. Each year the World Health Organization lists the virus strains likely to be most prevalent, which are included in the annual vaccine. One day they may be doing that for coronavirus too.
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