AstraZeneca vaccine, what we know so far: benefits, risks and indications for administration

AstraZeneca vaccine, what we know so far: benefits, risks and indications for administration
AstraZeneca vaccine, what we know so far: benefits, risks and indications for administration
Who developed the vaccine, how it works and when was it authorized – The AstraZeneca vaccine, renamed Vaxzevria March 25, is the result of a research that involved him Jenner Institute of the University of Oxford and its spin-out company, Vaccitech, in collaboration with the Anglo-Swedish company AstraZeneca and the Italian IRBM Science Park.

It uses a viral vector based on a weakened version of the common cold virus (adenovirus) that causes infections in chimpanzees and contains the “genetic material” that encodes the SARS-CoV-2 virus Spike protein. Following inoculation of the vaccine in a healthy person, the surface spike protein is produced by the body, stimulating the immune system to attack the SARS-CoV-2 virus if it later infects the body.

In December the vaccine entered thelast phase of experimentation and on the 30th of the same month it was approved for use in the UK vaccination program. There first vaccination was administered on January 4, 2021. On 12 January 2021, the EMA received the application for conditional marketing authorization from AstraZeneca, the positive opinion of the Agency arrived on 29 January.

Effectiveness and cost – The efficacy of the AstraZeneca vaccine in developing neutralizing antibodies against the virus in vaccinated individuals was found to be 62,6% in preliminary clinical trials. However, the protection against the development of severe forms of the disease was greater.

The EU, according to the European Commission’s Director-General for Health Sandra Gallina at the hearing in the Budget Committee of the European Parliament in Brussels, he pays AstraZeneca for each dose of anti Covid vaccine more than 1.78 euros, a figure that emerged in December, when the Belgian MEP Eva De Bleeker made public (by mistake) the prices of the single doses, still covered by secrecy.

Side effects, risks and benefits: the EMA decision of 7 April – On April 7, the EMA published a new report in which it recognized a “strong link” between vaccine administration anti-Covid by AstraZeneca and some extremely rare cases of cerebral and abdominal thrombotic eventsassociated with a deficiency of blood platelets.

The Ema has analyzed in depth 62 cases of Cvst (Cerebral thrombosis of the venous sinuses) e 24 cases of abdominal thrombosis (Splanchnic vein thrombosis), reported until March 22, 2021, of which 18 with a fatal course, and this on 25 million people vaccinated in the European Economic Area (EU plus Norway, Iceland and Lichtenstein) and in the United Kingdom. But in total, 169 cases reported up to April 4 were for cerebral thrombosis, and 53 for abdominal thrombosis, out of 34 million vaccinated people. The EMA therefore concluded that these thromboses combined with low platelet levels should be listed among the very rare possible side effects of the AstraZeneca drug.

At the same time, the EMA stressed that contracting the virus presents a far greater risk of mortality than the possible adverse effects of the vaccine. confirming the clearly positive opinion on the risk-benefit ratio of the vaccine and its efficacy against the SARS-CoV-2 coronavirus.

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Risk factors, categories concerned and limitations – No specific risk factor has yet been identified, although at the moment the cases in Europe mainly concern women under 55-60 years old, within an interval of two weeks after the administration of the vaccine. As for a possible link between thrombosis and estrogen, and in particular with the use of female contraceptives, the EMA specified that “there is no way to indicate that contraceptives o la pregnancy are a risk factor for these specific cases that we have observed “.

In light of the information currently available, according to the EMA it is not possible to indicate age or sex, or even pre-existing pathologies, as possible risk factors, and therefore no limitation regarding specific groups in vaccine administration has so far been recommended.

Cases of thrombosis after administration of other vaccines – Cases of thrombosis – EMA announced on 7 April – have also been reported after the administration of other vaccines authorized in the European Union, in addition to those of AstraZeneca, even if they are in relation to non-homogeneous data regarding the reference populations : 35 cases for Pfizer-BioNTech’s Comirnaty vaccine, out of 54 million people vaccinated in the European Economic Area; 5 cases for Moderna vaccine on 4 million people vaccinated in the world; and as for Johnson & Johnson (which is the only one of the other vaccines available today in the EU to use a viral vector like AstraZeneca’s) there are 3 cases out of 4.5 million people vaccinated in the world.

Symptoms and “remedies” – Patients who have received AstraZeneca vaccine doses are advised to monitor for possible abnormal symptoms (shortness of breath, chest pain, leg swelling, persistent abdominal pain, neurological symptoms such as severe headaches or blurred vision, subcutaneous blood spots at the site of the injection) that can occur after the vaccine for complications and adverse events, and seek immediate medical attention if they arise.

The EMA has “discussed at length with the experts also i possible treatments“for these rare thromboses.” What emerged – claims the European drug agency – is that health professionals they must not use heparin if they suspect they are dealing with one of these cases. Others anticoagulants they could perhaps be used, but on this the scientific opinions are not on the same line. Other possible treatments include immunoglobulins, steroids and plasmapheresis.

The choices of the countries after the EMA report – Germany, Spain and Belgium have decided to use it over 60, France over 55. Great Britain has recommended offering a different vaccine to people under 30. While the United States, Anthony Fauci said, does not plan at the moment to use the Oxford vaccine: “It is not a negative opinion on the serum – specified the American immunologist – but we already have three good vaccines that probably provide us with sufficient doses. also for a further recall “.

It’s Italy? – The new circular with which the Ministry of Health updated AstraZeneca’s Vaxzevria vaccine recommendations reiterating that the vaccine is approved from 18 years of age. “On the basis of current evidence, taking into account the low risk of adverse reactions of the thromboembolic type in the face of the high mortality from Covid in the most advanced age groups – it reads – it is recommended its preferential use in people over 60 years“.

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And who should take the second dose? – For now, the orientation of AIFA, the Italian drug agency, confirmed by the circular of the Ministry of Health, is to do conclude immunization with AstraZeneca for the recipient of the first dose no case of thrombosis was reported after administration of the second dose.

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