Vaxzevria, the COVID-19 vaccine developed by the University of Oxford and AstraZeneca, can cause some of the mostly mild to moderate side effects that people often encounter after any vaccination. However, there have also been recent controversies surrounding rare blood clotting incidents related to this vaccine.
The Oxford-AstraZeneca COVID-19 vaccine – also known as Vaxzevria, from 25 March 2021 – is a two-dose vaccine developed jointly by the Oxford Vaccine Group and the pharmaceutical company AstraZeneca to control the SARS-CoV-2 virus rig.
Serum Institute of India’s COVID-19 vaccine, called Covishield, is a version of the Oxford-AstraZeneca vaccine manufactured locally in India.
According to AstraZeneca’s primary analysis of phase 3 trial data, the vaccine has a 76% efficacy rate after both doses.
On 29 January 2021, the European Commission, on the recommendation of the European Medicines Agency (EMA), granted the ‘conditional marketing authorization’ vaccine in the European Union to adults aged 18 and over. The
This viral vector vaccine contains the gene encoding the vein protein on the surface of the SARS-CoV-2 virus. Once it is transferred to our cells, the gene is transcribed, which our cells must make spike proteins. The presence of this protein causes the body’s immune system to produce antibodies to fight the protein, which then prepares the body to fight SARS-CoV-2 as it enters the body.
Note that the vaccine does not contain the SARS-CoV-2 virus itself and does not cause COVID-19.
According to the safety profile of the vaccine within the product information, the most common side effects include mild to moderate symptoms of one or more of the following:
- headache (52.6%)
- fatigue (53.1%)
- muscle or joint pain (44% or 26.4%)
- fever (33.6%)
- cold fever (31.9%)
- nausea (21.9%)
The percentages are based on reports from four clinical trials with a total of 23,745 participants.
Individuals also usually reported pain and irritation at the site of vaccination.
In addition, an allergic reaction to certain ingredients in the vaccine may occur. Symptoms of an allergic reaction may include hives, rash, swelling and respiratory symptoms.
There have also been a few cases of anaphylaxis, which refers to a severe and potentially life-threatening allergic reaction. However, anaphylaxis is a very rare occurrence.
According to the Medicines & Healthcare Products Regulatory Agency (MHRA), out of 19.5 million doses of Vaxzevria administered, only 455 (0.002%) were associated with an anaphylaxis-related side effect.
People who are allergic to one of the ingredients – the active ingredient itself or any ingredients listed under the list of excipients in the product information – are advised against receiving the vaccine.
All of the side effects listed above are similar to those associated with other vaccines, such as the
In early March 2021, the Danish health authority thwarted the vaccination with Vaxzevria following reports of serious cases of blood clots.
The EMA noted that 30 cases of blood clots, or thrombosis, occurred after the administration of Vaxzevria to about 5 million people in the European Economic Area. This included one fatal case in Denmark.
In particular, the EMA observed thrombosis cases along with thrombocytopenia, which is a condition of low platelet counts. It has also observed several types of thrombosis, including unusual cases of cerebral venous sinus thrombosis, which is a rare occurrence of blood clots in the brain.
The EMA’s safety committee concluded on 7 April 2021 that unusual low blood platelet clots should be listed as very rare side effects of Vaxzevria, indicating a possible causal link.
However, the EMA states that the benefits of the vaccine outweigh the risks of preventing SARS-CoV-2 infection.
According to the MHRA, as of March 31, there were 79 reports of blood clotting cases with low platelet levels. All of these cases occurred after the first dose was administered, and 19 were fatal.
Of the 79 cases, 51 occurred in women, and most occurred in those under the age of 50 years. However, the MHRA noted that a greater number of women than men received Vaxzevria overall.
Although the regulatory agencies have not listed specific risk factors for blood clotting, the EMA suggests that the combined incidence of blood clots and low platelet counts may be a type of immune response.
The regulatory agencies advise individuals and healthcare professionals to pay attention to the symptoms of thrombosis, to ensure prompt detection and treatment.
Some symptoms associated with thromboembolic events include:
- short of breath
- chest pain
- leg swelling
- stomach pain
- neurological symptoms, including headache and blurred vision
- small blood stains under the skin beyond the vaccination site
Currently, 83 countries have approved COVID-19 vaccinations with Vaxzevria.
For live updates on the latest developments regarding the new coronavirus and COVID-19, click here.