News coincides with launch of trials to test effectiveness of modified jab against virus variant
Receiving a third dose of the Oxford-AstraZeneca Covid vaccine induces a strong immune boost against the virus, new data suggest, raising hopes that existing vaccines can be used effectively for booster jabs.
As part of a University of Oxford preprint study—which has not yet been peer-reviewed—some 90 people received a third dose of the vaccine.
The study found that in participants who received a third jab more than six months after their second shot, antibody levels were significantly higher than after a second dose.
There was also an increase in the number of antibodies capable of neutralising the Alpha, Beta and Delta variants.
“For the first time, we demonstrate that a third dose of [the vaccine] can induce a strong boost to immune responses to the […] Sars-CoV-2 spike protein, and that these responses result in higher neutralising antibody titres and enhanced activity against variants,” the research found.
“Here we show that a third dose of [the Oxford AstraZeneca vaccine] is well tolerated and significantly boosts the antibody response,” said Teresa Lambe, lead senior author for the study. “This is very encouraging news, if we find that a third dose is needed.”
It comes after the University of Oxford and AstraZeneca began human trials to test the effectiveness of a modified version of its Covid-19 vaccine against the so-called Beta variant of Covid.
The Phase II/III trial, which started on 27 June, is sponsored and led by AstraZeneca and will recruit approximately 2,250 participants from the UK, South Africa, Brazil and Poland. The new vaccine could be used in combination with the current Oxford-AstraZeneca vaccine to provide greater protection.
Andrew J Pollard, chief investigator and director of the Oxford Vaccine Group at the University of Oxford, said: “Testing booster doses of existing vaccines and new variant vaccines is important to ensure we are best prepared to stay ahead of the pandemic coronavirus, should their use be needed.”
Maheshi Ramasamy, principal investigator at the Oxford Vaccine Group, added that the study will “provide vital evidence on whether further doses including ‘tweaks’ against new virus variants may be needed in the future”.
The University of Oxford said initial data from the trial is “expected later this year” and, once available, will be “submitted to regulators for assessment as a next-generation booster vaccine and through an expedited regulatory pathway”.
Genome sequencing ‘milestone’
Elsewhere, the government announced that the UK has surpassed over half a million genomically sequenced positive coronavirus tests, which helps detect new and emerging virus variants.
“This milestone is testament to the hard work, dedication and brilliance of researchers and scientists in laboratories across the country, as well as those on the frontline of our battle against this wretched virus,” said health department’s innovation minister, Lord Bethell.
In the early stages of the pandemic the Covid-19 Genomics UK Consortium was created to deliver genome virus sequencing to local NHS centres and the government. Sequencing is now being delivered through a programme within UK Health Security Agency building upon the work of the consortium.
“Sequencing genomes has been one of most versatile tools in our armoury in the battle against Covid-19, and as we progress down the roadmap its role only increases in importance—helping us track mutations in the virus and act decisively to stop cases becoming outbreaks,” said UKHSA chief executive Jenny Harries.
The government said the UK’s New Variant Assessment Programme is supporting countries that make use of the UK’s genomic sequencing technology to spot new variants, providing them with technical support as well as upskilling their scientists with training.
Harries added: “The UK has shared its exceptional genomics capabilities with the world during this global pandemic and our expertise in this field will be at the heart of our mission at the UK Health Security Agency.”