AstraZeneca Vaccine Sharply Reduces Symptomatic COVID-19 In Older Adults; India’s ‘Covaxin’ Vaccine Reported To Be 81% Efficacious – First Interim Analysis
AstraZeneca vaccine found effective in reducing COVID-19 in older adults

The AstraZeneca/Oxford vaccine can reduce severe COVID-19 in older adults by up to 70%, says a new Public Health England (PHE) study – which offers the first real-world evidence of the effectiveness of the vaccine in preventing serious disease among older adults, following its approval by UK and European regulatory agencies. 

Findings about the efficacy of the AstraZeneca/Oxford vaccine in among older people are critically important for countries not only in Europe but also in Asia and Africa – where the vaccine’s efficacy has been a matter of debate – even as it starts to be rolled out massively through the WHO co-sponsored COVAX global vaccine initiative.  

Meanwhile, an indigenous Indian COVID vaccine showed an “efficacy trend of 81%”  in a Phase 3 trial involving some 25,800 people, according to a statement Wednesday by the Indian Council of Medical Research.  The “interim analysis” involved some 6,000 participants, including mostly older people and people who had chronic diseases.

Among the 46 participants who contracted COVID, 36 had been given a placebo, said Bharat Biotech, the company that co-developed the vaccine.  

“The interim efficacy trend of 81%, analyzed as per the protocol approved by the DCGI, puts it at par with other global front-runner vaccines,” stated the ICMR press release.  It quoted ICMR’s director general as saying: “The bench-to-bedside journey of [a] completely indigenous COVID-19 vaccine in less than 8 months’ time … is a testament to India’s emergence as a global vaccine superpower.” 

UK Findings Relevant For Europe, Asia and Africa – Where AstraZeneca’s Efficacy had been Questioned 
AstraZeneca’s COVID vaccine will be the bulk of the COVAX products shipped to Africa

With regards to the AstraZeneca vaccine, preliminary findings from the Public Health England study, pre-released Monday in draft form, should provide welcome reassurance to other national health authorities rolling out the vaccine. 

“The effect of a single dose of the ChAdOx1 [AstraZeneca/Oxford] vaccine against symptomatic disease was approximately 60-75% and there was again an additional protective effect against hospitalisation, though it is too early to assess the effect and mortality,” state the study’s authors. 

Among older people aged 70 and above, who received the first dose of the AstraZeneca/Oxford vaccine, effectiveness against symptomatic disease was approximately 60-75% – although the paper did not assess the effectiveness of the full two-dose vaccine regimen. 

The study also looked at impacts from the Pfizer vaccine, finding that one vaccine dose prevented up to 70% of symptomatic disease. For two Pfizer doses, effectiveness was up to 90% among older adults. 

PHE Study Should Build AstraZeneca Vaccine Confidence – In Europe as well as Asia & Africa 
COVID-19 vaccination of elderly in India

While the Pfizer vaccine has already demonstrated its effectiveness in reducing serious illness and mortality among older adults in a number of large Israeli studies, the UK data represents the first real-world findings on the efficacy of the AstraZeneca/Oxford vaccine since the vaccine was approved by regulators in the UK as well as the European Medicines Agency. 

A number of European governments had last month recommended against using the AstraZeneca/Oxford vaccine among older age people – due to what authorities then described as a lack of evidence following approval by the European Medicines Agency. 

French President Emmanuel Macron even went so far to describe the vaccine as “quasi-ineffective for people over 65”. The Swiss regulatory agency, Swissmedic refused to approve the vaccine altogether, saying that the data so far was “not yet sufficient to permit authorization.’’ 

On 10 February, however, the World Health Organization recommended the vaccine’s use across all age groups. The WHO expert group expressed  “high confidence” efficacy among the +65 age group. The experts noted that even though the numbers of older people involved in AstraZeneca’s Phase 3 studies had been small – their immune response had been almost as good as that of younger people. 

In Africa, the Oxford/Astra Zeneca vaccine is set to be a cornerstone of the first phase rollout of COVID vaccine deliveries by the WHO co-sponsored COVAX vaccine facility initiative. The first shipments of AstraZeneca vaccines  reached Ghana and the Ivory Coast on Monday, followed by Nigeria later this week.   

In India, the AstraZeneca vaccine is a cornerstone of the national campaign – along with the Covaxin indigenous vaccine.

Study Shows Vaccines Are Effective Against so-Called British SARS-CoV2 Variants 

The PHE results also are reassuring insofar as they reflect the efficacy of both Pfizer and AstraZeneca/Oxford vaccines against the so-called British (B.117) variant that has now become dominant in the country – also spreading widely across Europe and beyond.  

The study results do not, however, provide evidence about the vaccine’s efficacy against another variant that has become a major concern due to its apparently greater ability to elude the body’s immune response – and that is the B.1351 variant first identified in South Africa. 

Earlier findings from a small South African study found that the AstraZeneca/Oxford vaccine was ineffective in preventing mild and moderate disease among younger age groups – prompting the country to rapidly shift its vaccine campaign from AstraZeneca/Oxford to Johnson & Johnson – which just received US FDA regulatory approval. 

The UK was the first country to implement a COVID-19 vaccination campaign following the approval of the Pfizer-BioNtech messenger RNA (mRNA) vaccine, BNT162b2. The UK was also the first high-income country to approve and begin rolling out the AstraZeneca adenovirus-vector vaccine, ChAdOx1 nCOV-19.  

“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,” said Mary Ramsay, PHE Head of Immunisation, in a comment on the study. 

Pfizer Vaccine Also Offers High Levels of Protection Against Asymptomatic COVID  
Vaccination of the UK’s healthcare workers and elderly began in December 2020

In another UK study among healthcare workers, the Pfizer vaccine was shown to provide high levels of protection against any form of infection – preventing up to 85% of those immunized  from developing asymptomatic forms of COVID-19  as well.  

The study is important because it shows that the vaccines can also help stop the wider cycle of COVID transmission, as well as preventing symptomatic and serious disease. 

Healthcare workers in the study are regularly tested for coronavirus every 2 weeks, whether or not they have symptoms. Early data from the PHE SIREN study showed a single dose of the Pfizer vaccine had efficacy of up to 70% in preventing asymptomatic disease, rising up to 85% following the second dose. 

Even so, Ramsay cautioned: “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 really important that you continue to act like you have the virus, practise good hand hygiene and stay at home.”

Image Credits: Gilbert Mercier/Flickr, Tim Reckman/Flickr, BNarayanpatna/Twitter, Eric Fiegl-Ding/Twitter.

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