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Single shot of AstraZeneca or Pfizer-BioNTech vaccines reduce hospital treatment for elderly

A single shot of either the Oxford-AstraZeneca or the Pfizer-BioNTech COVID jab reduces the chance of needing hospital treatment by more than 80%, an analysis in England shows. Public Health England (PHE) has submitted a pre-print of a real-world study that shows that both the Pfizer and Oxford-AstraZeneca vaccines are highly effective in reducing COVID-19 infections among older people aged 70 years and over. Since January, protection against symptomatic COVID, 4 weeks after the first dose, ranged between 57 and 61% for one dose of Pfizer and between 60 and 73% for the Oxford-AstraZeneca vaccine.

The pre-print article compares the rate of vaccination in symptomatic people aged over 70 years of age who test positive for COVID-19, compared to those who test negative; compares the rate of hospitalisation in confirmed COVID-19 cases aged over 80 who were vaccinated more than 14 days before testing positive; compared to unvaccinated cases; and compares the rate of deaths in confirmed COVID-19 cases aged over 80 who were vaccinated with Pfizer vaccine more than 14 days before testing positive compared to unvaccinated cases.

In the over 80s, data suggest that a single dose of either vaccine is more than 80% effective at preventing hospitalisation, around 3 to 4 weeks after the jab. There is also evidence for the Pfizer vaccine, which suggests it leads to an 83% reduction in deaths from COVID-19.

The data also shows symptomatic infections in over 70s decreasing from around 3 weeks after one dose of both vaccines.

The new analysis adds to growing evidence that the vaccines are working and are highly effective in protecting people against severe illness, hospitalisation and death.

Dr Mary Ramsay, PHE head of immunisation, said: “This adds to growing evidence showing that the vaccines are working to reduce infections and save lives.

“While there remains much more data to follow, this is encouraging and we are increasingly confident that vaccines are making a real difference.

“It is important to remember that protection is not complete and we don’t yet know how much these vaccines will reduce the risk of you passing COVID-19 onto others.

“Even if you have been vaccinated, it is it is really important that you continue to act like you have the virus, practise good hand hygiene and stay at home.

From this week, the National Health Service (NHS) has started to deliver second doses to those people vaccinated first, which will provide higher and longer lasting protection.

Separate studies in healthcare workers show that one dose of the vaccine is preventing people from catching asymptomatic COVID-19 by at least 70%. This will help to reduce the spread of infection in hospitals and care homes, ultimately offering more protection to these vulnerable populations.

 

Study details
Early effectiveness of COVID-19 vaccination with BNT162b2 mRNA vaccine and ChAdOx1 adenovirus vector vaccine on symptomatic disease, hospitalisations and mortality in older adults in the UK: a test negative case control study

Jamie Lopez Bernal, Nick Andrews, Charlotte Gower, Chris Robertson, Julia Stowe, Elise Tessier, Ruth Simmons, Simon Cottrell, Richard Roberts, Mark O’Doherty, Kevin Brown, Claire Cameron, Diane Stockton, Jim McMenamin, Mary Ramsay

Abstract
Objectives
To estimate the real-world effectiveness of the Pfizer/BioNTech BNT162b2 vaccine and Astrazeneca ChAdOx1 vaccine against Confirmed COVID-19, hospitalisations and deaths. To estimate effectiveness on the UK variant of concern.
Design
Test negative case control design
Setting
Community COVID-19 PCR testing in England Participants All adults in England aged 70 years and older (over 7.5 million). All COVID-19 testing in the community among eligible individuals who reported symptoms between 8th December 2020 and 19th February 2021 was included in the analysis.
Interventions
One and two doses of BNT162b2 vaccine. One dose of ChAdOx1 vaccine.
Main outcome measures
Symptomatic PCR confirmed SARS-CoV-2 infection, hospitalisations and deaths with COVID-19.
Results
Individuals aged >=80 years vaccinated with BNT162b2 prior to 4th January, had a higher odds of testing positive in the first 9 days after vaccination (odds ratio up to 1.48, 95%CI 1.23-1.77), indicating that those initially targeted had a higher underlying risk of infection. Vaccine effectiveness was therefore estimated relative to the baseline post-vaccination period. Vaccine effects were noted from 10-13 days after vaccination, reaching an effectiveness of 70% (95% CI 59-78%) from 28-34 days, then plateauing. From 14 days after the second dose a vaccine effectiveness of 89% (95%CI: 85-93%) was seen.
Individuals aged >=70 years vaccinated from 4 th January had a similar underlying risk of COVID-19 to unvaccinated individuals. With BNT162b2, vaccine effectiveness reached 61% (95%CI 51-69%) from 28-34 days after vaccination then plateaued. With the ChAdOx1 vaccine, vaccine effects were seen from 14-20 days after vaccination reaching an effectiveness of 60% (95%CI 41-73%) from 28-34 days and further increasing to 73% (95%CI 27-90%) from day 35 onwards. On top of the protection against symptomatic disease, cases who had been vaccinated with one dose of BNT162b2 had an additional 43% (95%CI 33-52%) lower risk of emergency hospitalisation and an additional 51% (95%CI 37-62%) lower risk of death. Cases who had been vaccinated with one dose of ChAdOx1 had an additional 37% (95% CI 3-59%) lower risk of emergency hospitalisation. There was insufficient follow-up to assess the effect of ChAdOx1 on mortality due to the later rollout of this vaccine. Combined with the effect against symptomatic disease, this indicates that a single dose of either vaccine is approximately 80% effective at preventing hospitalisation and a single dose of BNT162b2 is 85% effective at preventing death with COVID-19.
Conclusion
Vaccination with either a single dose of BNT162b2 or ChAdOx1 COVID-19 vaccination was associated with a significant reduction in symptomatic SARS-CoV2 positive cases in older adults with even greater protection against severe disease. Both vaccines show similar effects. Protection was This is a preprint report of new research that has not been certified by peer review maintained for the duration of follow-up (>6 weeks). A second dose of BNT162b2 provides further protection against symptomatic disease but second doses of ChAdOx1 have not yet been rolled out in England. There is a clear effect of the vaccines against the UK variant of concern.

 

England's deputy chief medical officer – Professor Jonathan Van-Tam – said the data offered a glimpse of how the vaccine programme "is going to hopefully take us into a very different world in the next few months". But he said in BBC News it was "absolutely critical" that second doses "are still part of the course of immunisation against COVID-19 and no less important".

Van-Tam stressed there was a "significant likelihood" that a second dose of a vaccine would "mature your immune response, possibly make it broader and almost certainly make it longer than it would otherwise be in relation to a first dose only.

Van-Tam said the decision to give the AstraZeneca vaccine to older people was "clearly vindicated".

 

[link url="https://www.gov.uk/government/news/new-data-show-vaccines-reduce-severe-covid-19-in-older-adults"]Public Health England material[/link]

 

[link url="https://khub.net/documents/135939561/430986542/Early+effectiveness+of+COVID+vaccines.pdf/ffd7161c-b255-8e88-c2dc-88979fc2cc1b?t=1614617945615"]Study pre-print[/link]

 

[link url="https://www.bbc.com/news/health-56240220"]Full BBC News report (Open access)[/link]

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