Coronavirus vaccination
12:52 · 14 October 2021

Everything important you need to know about the AstraZeneca vaccine

Vaxzevria® by AstraZeneca is a vector-based COVID-19 vaccine. Read more information on the vaccine, its mode of action and possible vaccine reactions here.

The AstraZeneca® COVID-19 vaccine

The first vaccines against coronavirus have been authorised for use in Europe since December 2020. At the end of January 2021, the Vaxzevria® vector vaccine by AstraZeneca, too, received a so-called conditional marketing authorisation for the EU. This is not to be confused with an emergency use authorisation; it means that the authorisation is linked to certain conditions and that the use of the vaccine will continue to be subject to scientific observation. All of the important information on efficacy and vaccine recommendation

The vaccine at a glance

• Name: Vaxzevria®

• Marketing authorisation holder: the British-Swedish pharmaceutical company AstraZeneca

• Vaccine type + mode of action: Vector vaccine based on an attenuated cold virus (adenovirus) that was modified so as to introduce a blueprint of the virus into the body’s cells, inducing its immune system to produce antibodies.

• Efficacy: Once the recommendations by the Standing Committee on Vaccination (STIKO) are followed, Vaxzevria® provides an efficacy of up to 80 percent among vaccinated persons of all age groups after two shots. Current study results show a stronger immune response when a heterologous vaccination series (initial vaccination with Vaxzevria® and follow-up vaccination with an mRNA vaccine) is followed. The STIKO therefore recommends combining the vector-based vaccine with an mRNA vaccine.

• Vaccination recommendation: Based on the data currently available, the STIKO recommends Vaxzevria® for persons aged 60 and over. Persons who are younger are still entitled to receive the vaccine after being informed by a doctor and accepting personal responsibility for the risk. Moreover, persons who received Vaxzevria® as their initial vaccine should also, regardless of age, follow up with an mRNA vaccine) with an interval of at least a four weeks between shots. Specialists refer to this as a heterologous vaccination series. A second vaccine with Vaxzevria® (homologous vaccination schedule) remains possible, also for persons under the age of 60, after being informed by a doctor and accepting personal responsibility for the risk.

• Typical vaccine reactions: Headaches, pain in the limbs and joints, pain at the injection site, fatigue or flu-like symptoms

• Administration: by injection into the muscle of the upper arm (intramuscular)

• Vaccination schedule: two doses at least 4 weeks apart in the case of the heterologous vaccination series (initial vaccination with Vaxzevria®/follow-up vaccination with an mRNA vaccine), 9-12 weeks in the case of the homologous vaccination series (initial and follow-up vaccination with Vaxzevria®)

• Storage: protected from light at 2 to 8 degrees; do not freeze. Shelf-life (when stored unopened and refrigerated) is 6 months. After removal of the first dose, the shelf-life is a maximum of 48 hours when refrigerated.

This is how the vector vaccine works

Vaxzevria® by AstraZeneca consists of a so-called vector virus – a well-researched virus that is incapable of reproducing. Vaxzevria® by AstraZeneca is an adenovirus (a cold virus) that contains the genetic information for a single coronavirus protein: the so-called spike protein.

The information carried by the vector virus is “read” when it enters the cells (especially the muscle cells at the injection site and specific defence cells) leading these cells to subsequently produce the spike protein themselves. The immune system recognises the spike proteins thereby manufactured by the body as foreign proteins and consequently produces antibodies and defence cells to combat the virus. This is how a protective immune response comes about.

Good to know: The spike protein on its own is incapable of causing a SARS-CoV-2 infection. The body breaks down the vector virus after a short period of time, and subsequently the virus protein (spike protein) is no longer produced.

Studies confirm high efficacy

The AstraZeneca vaccine is highly efficacious and prevents COVID-19 infection among the majority of those vaccinated or alleviates their symptoms. If the interval of 9-12 weeks between the two shots is observed, as recommended by the STIKO, Vaxzevria® provides a high efficacy of up to 80 percent among vaccinated persons of all age groups (in the case of a homologous vaccination series with two doses of the Vaxzevria® vaccine). Efficacy in preventing severe cases of disease leading to hospitalisation and death is higher and stands at approximately 95 percent. To what extent boosters will become necessary at a later stage, as is the case with the influenza vaccine for example, is still being researched in the clinical trials.

Efficacy exceeds the minimum requirements

The World Health Organization (WHO) required an efficacy of at least 50 percent for the licensing of COVID-19 vaccines. With an efficacy of up to 80 percent, the AstraZeneca vaccine clearly exceeds requirements. This means that up to 80 percent of cases that occur without vaccination could be prevented. Furthermore, current studies show that the immune response after a heterologous vaccination schedule (initial vaccination with Vaxzevria®/follow-up vaccination with an mRNA vaccine) is stronger than after a homologous vaccination series (two doses of the Vaxzevria® vaccine). As a result, the STIKO has correspondingly supplemented its vaccination recommendation.

STIKO Recommendation

Based on the currently available data and bearing in mind the current pandemic situation, the STIKO recommends the AstraZeneca vaccine for persons aged 60 and over. However, younger people can also get immunised with Vaxzevria® if they decide to do so after being informed by a doctor and taking individual responsibility for the risks. Furthermore, the STIKO recommends a heterologous vaccination schedule for this vaccine, regardless of age. This means the initial vaccination should be conducted using Vaxzevria® and the follow-up vaccination after an interval of at least four weeks using an mRNA vaccine (BioNTech or Moderna).

Vaccine reactions and adverse reactions

The Vaxzevria® vaccine by AstraZeneca is reactogenic, meaning that vaccine reactions can occur after vaccination. Consequently, symptoms such as relatively severe headaches, pain in the limbs and joints, pain at the injection site, fatigue or flu-like symptoms can occur. This is known from clinical trials and is usually no reason for concern. Even when quite severe, as a rule the observed vaccine reactions abate after a few days. To mitigate possible complaints, you may take pain or fever-reducing medication in the dosage recommended by a doctor.

Find information on these possible adverse reactions, as well as additional important information in the information sheet on vector vaccines.

INFORMATION SHEET For vaccination against COVID-19 (Corona Virus Disease 2019) – with vector vaccine –

Advantages of vaccination

The occurrence of vaccine reactions and/or temporary adverse reactions is no reason to refrain from taking the vaccine; on the contrary, vaccinated persons benefit from the expected protection. Because it is clear that: an up to 80 percent protection after vaccination with the Vaxzevria® vaccine by AstraZeneca represents a significant individual benefit compared with absolutely no protection without vaccination. With regard to all of the currently available COVID-19 vaccines, the European Medicines Agency (EMA) has determined that the advantages of vaccination outweigh the risk of possible, very rare, adverse events and vaccination complications.

Safety continuously monitored

If you have known allergies to ingredients contained in the Vaxzevria® vaccine by AstraZeneca, or have had a severe allergic reaction to the first vaccine dose, you should refrain from taking a second dose. The safety of the COVID-19 vaccines is being monitored continuously: The Paul Ehrlich Institute continuously and transparently informs the public in its safety reports of all reported suspected cases of adverse reactions or vaccination complications that are temporally related to the COVID-19 vaccination in Germany.
Moreover, the following Infobox provides you with a summary of all the important information on the reported adverse reactions:

Possible undesirable adverse vaccination reactions

In several cases temporally related to the COVID-19 vaccination using the Vaxzevria® vaccine, a special form of severe cerebral venous sinus thrombosis in combination with a reduction in the blood platelet count (thrombocytopenia) and bleeding was observed. This is why, on 15 March 2021, the Paul Ehrlich Institute (PEI) had recommended that vaccination using the AstraZeneca vaccine be suspended as a precautionary measure to provide time to study the cases further. The Federal Ministry of Health then took the precaution of following this recommendation. The European Medicines Agency (EMA) subsequently examined the cases and after deliberation recommended that vaccination using the Vaxzevria® vaccine be continued, but information on the possible adverse reactions be provided. The PEI supports this recommendation.

This was the basis for the decision of 18 March 2021 to continue vaccinating with the Vaxzevria® vaccine. As additional cases of cerebral sinus venous thrombosis and other thrombotic events, such as mesenteric venous thrombosis pulmonary embolism among comparatively young vaccinated persons subsequently occurred, the STIKO updated its recommendation on 1 April 2021 recommending that Vaxzevria® be administered to persons aged 60 and over. However, it remains possible for persons under this age limit to receive the vaccine, after the person to be vaccinated has been informed by a doctor and has taken individual responsibility for the risk. The STIKO also currently advises persons who received an initial vaccination with the Vaxzevria® vaccine to obtain a follow-up vaccination with an mRNA vaccine after a minimum of 4 weeks. Here too, a follow-up vaccine using Vaxzevria® remains possible after the person has been informed by a doctor and accepted personal responsibility for the risk.

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