All the Details about Covid-19 Vaccine Oxford–AstraZeneca, Production, Emergency Use Approval & Efficiency

The Oxford–AstraZeneca COVID-19 vaccine, codenamed AZD1222, and sold under the brand names Covishield and Vaxzevria among others, is a viral vector vaccine for prevention of COVID-19. Developed by Oxford University and AstraZeneca, it is given by intramuscular injection, using as a vector the modified chimpanzee adenovirus ChAdOx1. The efficacy of the vaccine is 76.0% at preventing symptomatic COVID-19 beginning at 22 days following the first dose and 81.3% after the second dose. Another analysis conducted by Public Health England showed that the vaccine was 66.0% effective at preventing symptomatic COVID-19 after the second dose.

The vaccine has a good safety profile, with side effects including injection-site pain, headache, and nausea, all generally resolving within a few days. More rarely, anaphylaxis may occur (the UK Medicines and Healthcare products Regulatory Agency (MHRA) has 268 reports out of some 21.2 million vaccinations as of 14 April 2021). In very rare cases (around 1 in 100,000 people) the vaccine has been associated with an increased risk of blood clots in combination with low levels of blood platelets. According to the European Medicines Agency as of 4 April 2021, 222 cases of blood clots have been reported from the European Economic Area and the UK, where around 34 million people have received the vaccine.

On 30 December 2020, the vaccine was first approved for use in the UK vaccination program, and the first vaccination outside of a trial was administered on 4 January 2021. The vaccine has since been approved by several medicine agencies worldwide, such as the European Medicines Agency (EMA), and the Australian Therapeutic Goods Administration, and was approved for an Emergency Use Listing by the World Health Organization (WHO). Some countries have limited its use to elderly people at higher risk for severe COVID-19 illness due to concerns over the very rare side effects of the vaccine in younger individuals.

* Vaccine Composition:

The Oxford–AstraZeneca COVID-19 vaccine is a replication-deficient simian adenovirus vector, containing the full‐length codon‐optimised coding sequence of SARS-CoV-2 spike protein along with a tissue plasminogen activator (tPA) leader sequence.

The adenovirus is called replication-deficient because some of its essential genes were deleted and replaced by a gene coding for the spike protein. Following vaccination, the adenovirus vector enters the cells and releases its genes, which are transported to the cell nucleus; thereafter the cell's machinery does the transcription into mRNA and the translation into proteins.

The protein of interest is the spike protein, an external protein that enables the SARS-type coronavirus to enter cells through the enzymatic domain of ACE2. Producing it following vaccination will prompt the immune system to attack the coronavirus through antibodies and T-cells if it later infects the body.

* Efficacy:

An analysis published on 19 February 2021 showed an efficacy of 76.0% at preventing symptomatic COVID-19 beginning at 22 days following the first dose, increasing to 81.3% when the second dose is given 12 weeks or more after the first. Another analysis published by the Public Health England showed that the vaccine was 66.0% effective at preventing symptomatic COVID-19 2 weeks after the second dose.





A study published in April 2021 by researchers from the COVID-19 Genomics United Kingdom Consortium, the AMPHEUS Project, and the Oxford COVID-19 Vaccine Trial Group indicated the Oxford–AstraZeneca vaccine showed somewhat reduced efficacy against infection with the Lineage B.1.1.7 variant (70.4% efficacy in absolute terms versus 81.5% against non-B.1.1.7 lineages). Despite this, the researchers concluded that the vaccine remained effective at preventing symptomatic infection from this variant and that individuals infected symptomatically typically had shorter duration of symptoms and less viral load, thereby reducing the risk of transmission. Following the identification of notable variants of concern, concern arose that the E484K mutation, present in the Lineage B.1.351 and the Lineage P.1 variants, could evade the protection given by the vaccine. In February 2021, the collaboration was working to adapt the vaccine to target these variants, with the expectation that a modified vaccine would be available "in a few months" as a "booster" given to people who had already completed the two-dose series of the original vaccine.

* Manufacturing:

The vaccine is stable at refrigerator temperatures and costs around US$3 to US$4 per dose. On 17 December 2020, a tweet by the Belgian Budget State Secretary revealed that the European Union (EU) would pay €1.78 (US$2.16) per dose, The New York Times suggesting the lower price might relate to factors including investment in vaccine production infrastructure by the EU.

As of March 2021 the vaccine active substance (ChAdOx1-SARS-COV-2) is being produced at several sites worldwide, with AstraZeneca claiming to have established 25 sites in 15 countries. The UK sites are Oxford and Keele with bottling and finishing in Wrexham. Other sites include the Serum Institute of India at Pune. The Halix site at Leiden was approved by the EMA on 26 March 2021, joining three other sites approved by the EU.- Published by The Beyond News (Breaking News).

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