Unlike the mRNA vaccines from Moderna and Pfizer/BioNTech, AstraZeneca is a vector vaccine. This means that another weakened virus is used in it as a “vector” to transport particles of the pathogen (SARS-CoV-2 virus) to stimulate an immune response in the body.

AstraZeneca’s vaccine is based on a hybrid of an adenovirus molecule (a safe cold virus) and the genome of the SARS-CoV-2 virus. Through vaccination, these “instructions” are delivered to cells in the vaccinated body, which begin to produce a protein characteristic of the coronavirus (spike protein), leading to the formation of an immune response. This happens because the immune system recognizes the protein as foreign, producing antibodies and T-cells to it. This is how the body learns to defend itself when it encounters a real virus.

This is a well-studied and stable technology that makes vector vaccines safe. Another example of such a vaccine is the Ebola vaccine product.

The vaccine was developed by the Swedish-British pharmaceutical company AstraZeneca (registered in London) together with the University of Oxford. Currently, the vaccine produced in the EU has the brand name Vaxzevria. If it is made in South Korea, the drug is called AstraZeneca-SKBio, in India – Covishield. The drugs are absolutely identical in their composition, manufacturing technology and efficacy. hen Melinda Simmons specifically confirmed back in the spring that the CoviShield vaccine manufactured in India is absolutely identical to the Oxford/AstraZeneca drug.

Released in August, a large-scale study by scientists from the UK found that after two doses, the AstraZeneca vaccine was 69% effective (usually understood as protection against symptomatic disease in general). These results are based on an analysis of nearly 3.4 million PCR tests taken in 743,000 patients (on a rolling basis) between December 2020 and August 2021. They refer to both the Alpha and Delta strains.

When it comes to protection against hospitalization and severe COVID-19, AstraZeneca’s efficacy reaches 92% for the Delta strain and 86% for the Alpha strain in the case of a full course of vaccination, another study proved.

AstraZeneca side effects

The main feature of side effects from any coronavirus vaccine, including AstraZeneca’s, is that they are predictable, short-lived and may not lead to the development of COVID-19 disease (as a direct consequence of vaccination). Whereas the course of the disease for unvaccinated people is completely unpredictable.

The British government’s COVID-19 vaccination information website lists the most common side effects of the AstraZeneca vaccine and notes: most are “mild to moderate” and disappear within a few days.

The most common sensations complained of by patients (more than 1 in 10) were:

• pain, redness, itching, a feeling of swelling or bruising at the injection site;
• general malaise;
• feeling tired (fatigue);
• chills or feeling feverish;
• headache;
• nausea;
• joint or muscle pain.

“These reactions usually occur soon after vaccination and are not associated with more severe or long-term illness. The pattern of adverse reactions usually reflects the body’s normal immune response to vaccination,” explain the experts at the German institute.