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Coronavirus Vaccine AstraZeneca (Vaxzevria)

by Josephine Andrews
Published: Last Updated on 332 views

The Covid-19 vaccine from the manufacturer AstraZeneca called Vaxzevria (AZD1222) belongs to the class of vector vaccines. It has had provisional European market approval since January 29, 2021. Read here what is known about effectiveness, tolerability and application.

Current status of application: Is a third vaccination necessary?

A crossed vaccination scheme consisting of a first vaccination with Vaxzevria and a second mRNA vaccination protects against a severe course of Covid-19.

Doctors are nevertheless observing an increase in breakthrough infections in those who have been vaccinated twice because of the omicron variant. The Standing Vaccination Commission (STIKO) therefore recently changed its recommendations: It now recommends an additional third vaccination in order to continue to maintain the best possible vaccination protection against the omicron variant.

According to STIKO, another dose of an mRNA vaccine (BioNTech/Pfizer, Moderna) is suitable as a booster. For those under 30, the BioNTech vaccine should ideally be used.

What kind of vaccine is it?

The vaccine Vaxzevria (AZD1222) from the manufacturer AstraZeneca is the first approved vector vaccine against the disease Covid-19 in the European Union. He specifically trains the human immune system against the pathogen Sars-CoV-2. In clinical studies, Vaxzevria (AZD1222) provided good protection against Covid-19.

Vector vaccines belong to the class of genetic vaccines. In this case, the basis is a harmless cold virus (adenovirus) originating from chimpanzees, which serves as a so-called vector. For this purpose, the vaccine virus is equipped with a short section of the Sars-CoV-2 genome that contains the blueprint for the production of the spike protein.

With the vaccination, the blueprint enters the human cell. This then begins to produce the virus protein: It then presents it on its surface. The human immune system then forms antibodies and immune cells (T cells, B cells) against the spike protein. This learned immune response can protect the vaccinated person from an outbreak of Covid-19 in the event of an infection.

Vaxzevria (AZD1222) has European Medicines Agency (EMA) conditional marketing authorization for the European market. This means that the approval of Vaxzevria (AZD1222) is subject to conditions regarding safety and effectiveness. These requirements are continuously and closely monitored and checked by experts from the Paul Ehrlich Institute (PEI) and the EMA.

You can find out more about how vector vaccines work in our article on vector vaccines .

Efficacy against Covid-19

According to the RKI, the AstraZeneca vaccine is 80 percent effective. The protection against severe courses is almost 100 percent, especially for seniors.

Full protection by Vaxzevria (AZD1222) is achieved two weeks after the second dose.

Efficacy in mutations

According to the University of Oxford, the vaccine Vaxzevria (AZD1222) also offers protection against severe courses in the event of infection with the British variant B.1.1.7 . This was found in a study of 499 participants.

The authors found that those who had previously been vaccinated with the AZD1222 vaccine had significantly lower levels of virus than the control group when infected.

For more information on the currently circulating coronavirus variants, click here .

No admission for children and young people

Data on the effectiveness in children and adolescents up to the age of 18 are not available. The vaccine Vaxzevria (AZD1222) is therefore not approved for this age group in the European Union.

tolerability and side effects

AstraZeneca’s vaccine is generally well tolerated. However, any side effects that occur will continue to be closely monitored and continuously updated by the Paul Ehrlich Institute (PEI). Serious side effects associated with the AstraZeneca vaccination are still very rare.

However, there have been increasing reports of very rare cerebral vein thrombosis (sinus vein thrombosis) associated with a lack of blood platelets. In the meantime, Germany and other European countries are therefore only recommending vaccination in Germany for people over the age of 60 until further notice.

The Standing Vaccination Committee (STIKO) adjusted its vaccination recommendation on May 12, 2021 for younger people under the age of 60: People who have already received an initial vaccination with the AstraZeneca vaccine should receive an mRNA vaccine (Comirnaty , Moderna) received (heterologous vaccination scheme).

For more information on the combined vaccination of the AstraZeneca vaccine and the BioNTech vaccine, click here .

frequent side effects

However, about one in ten vaccinated people develop moderate side effects as a reaction to the vaccination. They correspond to those that usually occur after vaccinations. The side effects usually disappear within a few hours or days. This includes:

  • mild to moderate pain or swelling at the injection site
  • headache
  • exhaustion
  • joint pain
  • mild illness
  • chills
  • light fever

Serious side effects

Serious side effects, such as severe (anaphylactic) reactions, are very rare after vaccination.

cerebral vein thrombosis

However, various cases of rare, dangerous cerebral vein thrombosis have been observed, often in connection with a lack of blood platelets (thrombocytopenia). Some of the patients died from it. According to the data, about one in 100,000 vaccinated people is affected. The cerebral vein thrombosis occurred four to 16 days after vaccination and predominantly affected young and middle-aged women. Currently, AstraZeneca is therefore only vaccinated in people over 60 years of age.

Appropriate warnings will be included in the technical information and instructions for use in a timely manner.

When examining blood samples from affected patients, researchers at the University Medical Center Greifswald apparently found a possible cause for the incidents observed. Accordingly, in rare cases, thrombocytes are activated by the vaccination – similar to the processes involved in wound healing. This could be a possible explanation for the observed events. However, reliable data on this is still lacking.

The PEI emphasizes that all persons who feel increasingly unwell, develop pinpoint skin bleeding or severe persistent headaches after receiving a vaccination of Vaxzevria (AZD1222) should seek immediate medical attention.

Capillary Leak Syndrome

In addition, the manufacturer AstraZeneca recently reported on very rare cases of the so-called capillary leak syndrome (CLS), which occurred in a temporal connection with a Vaxzevria vaccination. A fatal case was named.

According to initial estimates, this severe form of side effect affects one case in around five million vaccine doses administered. According to the PEI, however, some of those affected already had a history of CLS. So there is now a contraindication for anyone who has been vaccinated who has previously had a CLS episode. They are no longer allowed to be vaccinated with Vaxzevria. During the preliminary talk about the vaccination, doctors should now ask about this.

CLS is considered a rare disease. It is characterized by a misdirected inflammatory response and dysfunction of the blood and lymphatic vessels. In this specific case, this means that the mechanisms of vasodilatation are disrupted for the duration of the CLS episode and the blood vessels become permeable.

As a direct result, the blood pressure of those affected drops rapidly and fluid flows into the tissues. This results in rapid weight gain with progressive swelling of the arms and legs. This in turn leads to a constant thickening of the blood (hemoconcentration), which can possibly lead to organ failure or shock.

The PEI points out that in rare cases, systemic CLS can also be triggered by Covid-19 infections.

transverse myelitis

In isolated cases, physicians report another very rare complication that has been observed in the temporal context of Vaxzevria administration (traverse myelitis, TM).

TM is a rare neurological condition in which the spinal cord of affected patients becomes inflamed. The reasons for this are still largely unknown, but an autoimmune reaction against the body’s own structures in the spinal cord is suspected.

Symptoms vary depending on which part of the spinal cord is affected. They range from sensory disturbances, exhaustion, malfunctions of the gastrointestinal tract, movement disorders to paralysis.

Although the documented reports are sporadic isolated cases, the European health authority still sees at least a possible connection between Vaxzevria vaccination and TM. However, the frequency of this complication is unknown.

In this context, the EMA emphasizes that despite these individual case reports, the risk-benefit ratio for Vaxzevria is still clearly positive.

Also compatible with allergies

According to the current state of knowledge, the vaccine is also suitable for allergy sufferers. However, allergy sufferers should inform their vaccinating doctor of known allergies before the vaccination. In the event of an allergic reaction, the doctor can take countermeasures quickly.

You should also remain in the practice or vaccination center for at least 15 minutes after the vaccination for medical monitoring

vaccination during pregnancy

There is no experience of using the vaccine in pregnancy. According to a preliminary assessment by the EMA, no harmful effects on the unborn child are to be expected from vaccination with Vaxzevria (AZD1222).

However, this assessment is based on preliminary studies in animal models. Reliable data on the effects and side effects during pregnancy are not yet available for Vaxzevria (AZD1222).

The decision as to whether vaccination makes sense during pregnancy should be clarified in close consultation with your doctor. He can best assess the benefits and risks for you.

Vaccination in case of illness

According to the EMA, you can get vaccinated if you have mild cold symptoms. In the case of a more serious illness, however, you should postpone an upcoming vaccination.

Vaccination and anticoagulants

People who take anticoagulants as a preventive measure should inform their doctor in advance. The general precautionary measures then apply: In the case of anticoagulant therapy, the vaccine must be administered with particular care.

Vaccination with immunodeficiency

How well Vaxzevria (AZD1222) works in patients with an immunodeficiency or drug suppressed immune system (immunosuppression) and how well it is tolerated by them is still unclear at the present time. Studies in this regard have not yet taken place. However, according to the EMA, it is possible that the effect of the vaccination could be less in patients with a weakened immune system.

storage and shelf life

In contrast to the already tested vaccines Comirnaty from the manufacturer BioNTech/Pfizer and the vaccine from Moderna, Vaxzevria (AZD1222) can be stored in the refrigerator for a long time.

The manufacturer’s maximum storage time in unopened condition is around six months. Vaxzevria (AZD1222) is supplied in dosed containers containing 8 or 10 doses of vaccine.

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