This vaccine was developed by researchers at the University of Oxford in collaboration with the British laboratory AstraZeneca. It is a “viral vector” vaccine: it is based on another virus (a chimpanzee adenovirus) that has been weakened and genetically modified to prevent the coronavirus from reproducing in the human body.
The way he introduces the genetic material into cells, ordering them to attack SARS-CoV-2, has been classified as a “Trojan horse”.
Practical and affordable
The AstraZeneca / Oxford vaccine has the advantage of being cheap (around 2.5 euros, or 3 dollars per dose, with variations depending on local production costs). AstraZeneca has undertaken to sell it at cost.
It is also easy to store: it can be kept in a refrigerator temperature, between 2ºC and 8ºC, unlike the Moderna and Pfizer / BioNTech vaccines, which can only be stored in the long term at very low temperatures (-20 ° C in the first case, and -70 ° C, in the second).
This facilitates large-scale vaccination.
Confusion about effectiveness
According to the British laboratory, the product has an average effectiveness of 70% (against more than 90% for Pfizer / BioNTech and Moderna), a result validated by the scientific journal The Lancet.
In the first published results, from clinical trials prior to its approval, there were variations in efficacy, according to the different doses administered by mistake, which sowed doubts and provoked criticism, leading the company to carry out additional studies.
Its effectiveness in people over 65 was also questioned in Europe due to lack of data, until new information, extracted from vaccination campaigns in the most advanced countries in this field, gave guarantees in this regard.
Several countries, such as Germany and Italy, have finally authorized it for this age group, hoping to speed up their immunization campaigns.
A study by health authorities in England showed protection of 60% to 73% against symptomatic forms of the disease in people over 70 years of age, with a single dose.
Possible serious but rare side effects are suspected after the detection of atypical cases of thrombosis in patients vaccinated with AstraZeneca.
Dozens of cases have been reported, some of which have resulted in deaths.
The UK has recorded 30 cases and seven deaths so far, out of a total of 18.1 million doses administered as of March 24.
No similar observations have been reported after applying millions of doses of the Pfizer / BioNTech immunizer.
According to the European Medicines Agency (EMA), “no causal relationship has been proven, but it is possible”, and the benefits of the coronavirus immunizer continue to outweigh the risks.
As a precaution, several countries have decided not to administer this vaccine under a certain age, such as Germany and the Netherlands (60 years old), France and Canada (55 years old), or Sweden and Finland (65 years old).
In turn, AstraZeneca said in March that “there is no evidence of an increased risk” of blood clots.
Delays in delivery
The British regulatory body, MHRA, was the first to approve its mass use. The country most affected in Europe by covid-19, with 125,000 deaths, the United Kingdom has ordered 100 million doses of this vaccine.
Delays in deliveries to the countries of the European Union have generated serious complaints, as the British laboratory supplied the United Kingdom with the promised stocks.
Italy recently blocked the export of 250,000 doses, citing “persistent shortages” and “delays in supply”.
European Commission President Ursula von der Leyen warned that other countries could block exports. And he stated that AstraZeneca delivered “less than 10%” of the doses ordered between December and March.
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