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Scientists from the UK and Russia will test whether the combination of injections of the Oxford / AstraZeneca and Sputnik V coronavirus vaccines could result in better protection than two doses of the same.
Testing will begin at the end of the year, the Russian Direct Investment Fund (RDIF), which funded the development of the Sputnik V vaccine by Russia’s Gamaleya Institute, said Friday. AstraZeneca confirmed that it was considering how to evaluate combinations of different vaccines and would soon begin to explore with the Gamaleya Institute whether its two vaccines could be successfully combined.
Like the Oxford / AstraZeneca vaccine, the Russian Sputnik V injection is based on a modified version of the adenovirus, a common cold virus. Any disease-causing gene is removed from this “vector” and modified to carry genetic instructions to produce the coronavirus spike protein, which is passed into human cells.
The manufactured coronavirus spike protein triggers an immune response that protects against Covid-19 disease.
However, a potential problem with such vaccines is that of “anti-vector immunity” where if the immune system has previously encountered the type of adenovirus used in the vaccine, it can destroy it before the vaccine can trigger an immune response. That’s why the Oxford University group chose to use a chimpanzee adenovirus, rather than a human one. However, anti-vector immunity could also reduce the effectiveness of booster injections, if this involves injecting the same virus a second or third time.
Mixing and matching different vaccines can provide a solution. This concept is known as heterologous prime-boost and has been used in vaccination programs against other diseases.
Fast guide
When and how will I be able to get the Covid vaccine in the UK?
Now that the UK has authorized the first Covid vaccine, who will get it first?
The government’s Joint Committee on Vaccination and Immunization (JCVI) says its priority is to prevent Covid-related deaths and protect health and social care personnel and systems.
Nursing home residents and their caregivers are first on the JCVI list because their risk of exposure to the virus is higher and because the risk of death is closely correlated with advancing age. They are followed as a priority by any other person over the age of 80 and front-line health and social care workers.
Still, for pragmatic reasons, NHS staff will likely be the first group to take the hit from Pfizer / BioNTech. This is because the vaccine must be stored at extremely cold temperatures, which can be more easily achieved using hospital facilities.
Are there enough doses to reach all priority groups?
Together, nursing home residents, their caregivers and those over 80 years old number nearly 6 million people, and frontline NHS staff 736,685 more. Matt Hancock, the health secretary, has said that he expects 10 million doses of the Pfizer / BioNTech vaccine to be available this year, so if this is the only licensed vaccine, everyone else would have to wait until there are more doses. available next year.
Where will I go for the vaccine?
Covid-19 vaccines are expected to be delivered to three types of locations: trusted NHS ‘vaccine centers’ in hospitals; mass vaccination centers, which are in the process of being installed in places such as football stadiums, conference buildings, and racetracks; they are expected to vaccinate up to 5,000 people a day; and in GP and pharmacy consultations. GPs are also able to visit nursing home residents and homebound patients without travel.
How far apart will the two doses be administered and will I be protected after the first?
While there is some evidence indicating high levels of short-term protection with a single dose of vaccine, a two-dose schedule is what has been approved by the MHRA.
The second dose should be given at least 21 days after the first, and both will be injected into the deltoid muscle, the thick triangular muscle that we use to lift each arm.
For the Pfizer vaccine, its efficacy rate was calculated seven days after the second injection. People will likely have some protection before this, but this is how long it will take for full protection to kick in. We will learn more about the scope of protection and how long it lasts as data from ongoing clinical trials arrives.
Can I pay for the vaccine privately?
Unlikely. England’s Deputy Chief Medical Officer Jonathan Van-Tam has said he believes Covid-19 vaccines should be administered according to clinical priority rather than allowing people to skip the queue if they can afford them.
Will I be able to choose which vaccine I have?
It is also unlikely, at least in the short to medium term. Assuming more than one vaccine is approved, the priority will be to distribute any available doses to people who need them as quickly as possible.
Linda Geddes
Unlike the AstraZeneca vaccine, Sputnik V uses two different human adenovirus vectors to try to elicit a stronger, longer-term immune response. It is not yet clear which of these components will be tested in conjunction with the AstraZeneca vaccine.
Anti-vector immunity could also provide a possible explanation for why the AstraZeneca vaccine seems to work better when given as a half dose followed by a full, rather than two full doses.
Earlier this week, outgoing UK Vaccine Task Force Chair Kate Bingham announced that a trial of the AstraZeneca vaccine in combination with the Pfizer injection was likely to begin in January. “It has to do with trying to activate the immune response and durability [of the response],” she said.
RDIF said it reached out to AstraZeneca about the possibility of combining its vaccines on November 23.
“This could eventually extend the duration of immunity and possibly also protect against people who receive the same vector repeatedly and have a less robust response,” said Beate Kampmann, director of the vaccine center at the London School of Hygiene and Tropical Medicine. “But for now, these are all theoretical concepts that need to be carefully tested before they can be extended to population use.”
Russia is likely to view the move as a vote of confidence from a Western maker of Sputnik V, which is already being used to immunize medical workers, teachers and social workers. Russian officials previously announced that the vaccine is more than 95% effective, giving it a success rate comparable to the vaccines being developed by Pfizer and Moderna.
“AstraZeneca’s decision to conduct clinical trials using one of the two Sputnik V vectors to increase the efficacy of its own vaccine is an important step in joining forces in the fight against the pandemic,” said Kirill Dmitriev, executive director of RDIF. “We hope that other vaccine producers will follow our example.”
Dr Stephen Griffin, Associate Professor at the University of Leeds School of Medicine, said: “The importance of a second puncture should not be underestimated as it is important for the longevity, specificity and efficacy of the response to most vaccines. “
