- Oxford vaccine reduces transmission by 67%
- Study shows the single dose of the vaccine is 76% effective for 3months
- 8-12weeks between does is the sweet spot of efficacy
- No clarity on efficacy on elderly people as of yet
- Europe flags it for lack of data on the elderly
- AstraZeneca chief Andrew Pollard have said that older people have same efficacy as younger people despite lack of clinical data
- People are protected from 22 days of the single dose vaccination.
An Oxford study has found that the AstraZeneca covid vaccine reduces covid transmission and hospitalisation as it was found to effective for 3months after single dose, reports the Telegraph.co.uk
The findings of the pre-print paper, which had not been peer-reviewed, supported Britain’s decision to extend the interval between initial and booster doses of the shot to 12 weeks, Oxford said on Tuesday.
Long Effective Immunity
Oxford University and AstraZeneca’s Covid-19 vaccine showed in a study it had 76% efficacy against symptomatic infection for three months after a single dose, which increased if the second shot is delayed, backing Britain’s vaccine rollout policy.
The results for the AstraZeneca/Oxford vaccine, gathered from trials in Britain, Brazil and South Africa, showed that immune responses were boosted with a longer interval to the second dose among participants aged 18 to 55 years.
No Clarity on Efficacy in Elderly People
However, the new study did not address concerns about a lack of data on efficacy among the oldest, who the British government have given highest priority in its vaccine rollout.
Andrew Pollard, Chief Investigator of the Oxford Vaccine Trial, said the data showed the 12-week interval between doses was “the optimal approach to roll out, and reassures us that people are protected from 22 days after a single dose”.
Britain has decided to vaccinate as many people as possible as quickly as possible by lengthening the amount of time between initial shots and booster shots to tackle the Covid-19 pandemic.
Sweet Spot of Efficacy
AstraZeneca’s research chief has said 8-12 weeks between doses seems to be the “sweet spot” for efficacy, contrasting with US drugmaker Pfizer, which has warned that the vaccine it has developed with Germany’s BionTech was not trialled with such an interval.
The results for the AstraZeneca/Oxford vaccine, gathered from trials in Britain, Brazil and South Africa, showed that immune responses were boosted with a longer interval to the second dose among participants aged 18 to 55 years.
“Vaccine efficacy after a single standard dose of vaccine from day 22 to day 90 post vaccination was 76%, and modelled analysis indicated that protection did not wane during this initial 3 month period,” Oxford academics said in the preprint.
- The paper said that vaccine efficacy was 82.4% with 12 or more weeks to the second dose, compared to 54.9% for those where the booster was given under 6 weeks after the first dose.
- The longest interval between doses for those aged 56 and over was between 6-8 weeks, so there was no data for the efficacy of a 12 week dosing gap in that cohort.
Europe Red Flags It
Europe’s medicine regulator has flagged that there is not enough data to determine how well the vaccine will work in people aged over 55, but Britain has expressed confidence the vaccine works in all age groups.
The study said that no-one out of the 12,408 people vaccinated with a single dose of the vaccine was hospitalised with Covid-19 from 22 days after immunisation.
Oxford also said data seemed to suggest the vaccine reduced transmission of infections, with a 67% reduction in positive swabs among those vaccinated in the British arm of the trial.
Vaccine Chief Bats for It
According to a Reuters report, University and AstraZeneca gives good immune responses in older people, even if there is a lack of data about its exact efficacy, Oxford’s vaccine trial chief Andrew Pollard said on Wednesday
Asked about a reported comment from French President Emmanuel Macron that the vaccine is “quasi-ineffective” among people over 65, Pollard said, “I don’t understand what that statement means.”
“The point is that we have rather less data in older adults, which is why people have less certainty about the level of protection,” Mr Pollard told BBC radio.
“But we have good immune responses in older adults very similar to younger adults, the protection that we do see is in exactly the same direction, and of a similar magnitude.”
Mr Pollard said different countries would recommend that the shot is used in different contexts after France’s top health body recommended it only given to people under 65, but he pointed out the EU regulator had approved it for all ages.
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Source: The Telegraph
