What we know so far about the AstraZeneca COVID-19 vaccine


Scientists around the world are working to make one effective Covid19 vaccine. There is increasing concern around the AstraZeneca COVID-19 vaccine making it a controversial vaccine candidate.

The promise of the AstraZeneca COVID-19 vaccine

The AstraZeneca COVID-19 vaccine was developed in partnership with the University of Oxford shortly after the first lockdown in Canada and the US COVID-19 in March 2020. The vaccine contains a weak version of a common cold virus and essentially teaches the body how to fight the true COVID-19 virus.

According to the BBC, what makes the AstraZeneca vaccine unique is that this pharmaceutical company makes the vaccine cost effective to ensure doses can be delivered in low -income countries around the world, unlike other companies in the world. vaccine.1

Clinical testing of the AstraZeneca COVID-19 vaccine began on April 23, 2020. There were four randomized controlled studies in the UK, Brazil, and South Africa. A total of 11,636 individuals aged 18 and older participated in the study, receiving two different doses of the vaccine. Some participants received two identical doses of the vaccine, some received a smaller dose followed by a larger dose, and some individuals received a ‘control’ ingredient (not the vaccine). .

A report has been published that accompanies the progress of the clinical trial through November 4, 2020.2 In the group that received the vaccine, there were no hospital visits related to COVID-19. Of the group that did not receive the vaccine, there were 10 hospital visits due to COVID-19, of which two of them were severe cases of COVID-19, and one of the cases ended in death. The overall ability of the vaccine to protect against COVID-19 infection-its effectiveness-was found at that time to be 70.4% of the total. Its effectiveness was measured more than 14 days after participants received their second dose and confirmed a COVID-19 infection test.

A second report was published showing findings from the same group of participants, but the new cut-off date is December 7, 2020.3 There is still no COVID-19 associated with hospitalization for vaccine recipients. Of those not vaccinated, COVID-19-related hospitalizations increased to 15 people. The overall effectiveness was calculated at 66.7% time after 14 days of receiving the second dose.

As suggested by these reports, the AstraZeneca COVID-19 vaccine has been shown to have the potential to be protective against COVID-19 infection. However, some may argue that 70.4% or 66.7% is not enough to guarantee reliable vaccination in the world. Did AstraZeneca find ways to increase the effectiveness of their COVID-19 vaccine?

The optimistic dose of Astra Zeneca COVID-19 vaccine

Referring to the initial clinical trials of AstraZeneca in the UK, South Africa and Brazil, there were two groups that received the vaccine: some received two identical doses and some received a small dose followed by a larger dose. The group that received the smallest dose first showed more promise of fighting COVID-19 than the group that received two identical doses. How big is the impact of this vaccination plan?

The group that received first a small dose first a larger dose second had a calculated effectiveness of 90.0%, while the group that received two identical doses had an overall effectiveness of 62.1%. .2 These recovery calculations were performed at least 14 days after the second dose was given and confirmed with a COVID-19 infection test.

In terms of asymptomatic infection, the group receiving two unequal doses showed a 58.9% efficacy against COVID-19 infection, while the same dose group showed 3.8% efficacy against COVID-19. .2

The best application schedule for the Astra Zeneca COVID-19 vaccine

Throughout the initial clinical trial of the vaccine, both doses were given in different time increments. What did they find?

As of the cutoff on December 7, 2020 for data analysis, it was calculated that those who received a single standard dose had 76% protection against COVID-19 infection, and this measure of effectiveness did not vary from 22 to 90. days after vaccination.3 The presence of COVID-19 antibodies in the blood was also unchanged between days 22 to 90 after the first baseline dose. These data suggest that a single dose of the vaccine does not lose its effect until at least 90 days after vaccination.

If given the same second dose less than six weeks later, the vaccine has an effectiveness of 54.9%.3 When the second same dose was given more than 12 weeks ago, the vaccine had an effectiveness of 82.4%.3

Is the AstraZeneca COVID-19 vaccine safe for all age groups?

This initial clinical trial of the AstraZeneca COVID-19 vaccine focused on adults aged 18 and older. However, only 12.2% of those tested were over the age of 55.2 In order to make a more robust statement on the safety and impact of the vaccine in older people, more research needs to be done.

How is the Astra Zeneca COVID-19 vaccine currently used?

In the month of March, several countries restricted the distribution of the AstraZeneca vaccine, including Denmark, Norway, Iceland, Ireland, Germany, and Thailand. This is in response to reports that blood clots are rare in some individuals who have received the vaccine in European countries.

On March 11, 2021, the British Medical Journal reported that an Austrian individual who had received the vaccine had multiple blood clots and died in hospital.4 Another Austrian had blood in his lungs and was recovering in hospital. On March 10, Denmark reported a death due to blood clots after receiving the AstraZeneca vaccine. On March 14, Denmark and Norway also revealed that six individuals who had received the vaccine had experienced blood clots and low platelet counts and they were all under the age of 50. Blood clots can be fatal, and many in countries are wary of the answer.

The European Medicines Agency (EMA) published a review on March 31, 2021 of this blood pressure. They recognized that there was no evidence of a cause of thromboembolic events and the AstraZeneca COVID-19 vaccine. They also claim that because the vaccine works with almost 70% effectiveness, it is even more at risk of getting one of the rare blood clots.5

What statistics do we have?

As of March 11, 2021, there were five million people vaccinated in the European Economic Area, and of these people, 30 had experienced thromboembolic events.6 According to Vaccines Safety Lead for UK Medicines and Healthcare Products, Phil Bryan, of the 11 million vaccinated with the AstraZeneca COVID-19 vaccine in the UK, the rate of thromboembolic events is lower than the rate most expected. population.4 However, as of April 3, 30 cases of hemorrhage had been detected in the UK alone in individuals who had received the vaccine.

The U.S. conducted a phase III clinical trial of the vaccine, including 32,000 participants. AstraZeneca posted the results on March 25: the newly updated overall efficacy was 76%, with 100% efficacy against severe or critical hospitalization, and 85% symptom efficacy COVID-19 in the elderly 65+.7 However, these calculations were quickly documented and the results from the U.S. have not yet been made official due to the FDA’s desire to review the raw data. As of April 3, 2021, the vaccine has not yet been approved by the FDA.

On March 29, 2021, the Canadian National Advisory Committee on Immunization (NACI) adjusted AstraZeneca vaccine vaccination bans for those over the age of 55, as released by the CBC.8

EMA urges individuals concerned about blood clotting potential to check out the newly updated product information (hyperlink to https://www.ema.europa.eu/en/medicines/human/EPAR /vaxzevria-previously-covid-19 -vaccine-astrazeneca # product information section). Even if the EMA does not recognize a significant relationship between blood pressure and the Astra Zeneca vaccine, they urge vaccine recipients to be aware of the risk based on cases seen in Europe.5

The AstraZeneca websites feature COVID-19 vaccine information tailored to vaccine recipients and healthcare professionals that vary depending on geographic area. Please visit https://www.azcovid-19.com/ for more information.

Bottom line

If you are scheduled to receive AstraZeneca vaccine and are concerned about how it may affect you, talk to your doctor. It is important to know your own risk when choosing a COVID-19 vaccine.

  1. Walsh, F. (March 25, 2021). Covid vaccine: AstraZeneca updated vaccine effectiveness results in the US. BBC News. Accessed April 2, 2021. Retrieved from https://www.bbc.com/news/world-us-canada-56521166.
  2. Voysey, M. et al. (2020). Safety and efficacy of the ChAdOx1 nCoV-19 (AZD1222) vaccine against SARS-CoV-2: an interim analysis of four randomized controlled trials in Brazil, South Africa, and the UK. The Lancet; 397 (10269): P99-111. Doi: 10.1016 / S0140-6736 (20) 32661-1.
  3. Voysey, M. et al. (2021). Single Dose Administration, and the Influence of Booster Dose Time on the Immunogenicity and Effectiveness of ChAdOx1 nCoV-19 (AZD1222) Vaccine. The Lancet-PrePrint. Available with SSRN: https://ssrn.com/abstract=3777268. Doi: http://dx.doi.org/10.2139/ssrn.3777268.
  4. Wise J. (2021). Covid-19: European countries have suspended use of the Oxford-AstraZeneca vaccine following reports of blood damage. The British Medical Journal; 372: n699. Two: .10.1136 / bmj.n699.
  5. AstraZeneca COVID-19 vaccine: ongoing review of very rare cases of unusual hemorrhage. (March 31, 2021). European Medical Agency. Accessed April 2, 2021. Retrieved from https://www.ema.europa.eu/en/news/astrazeneca-covid-19-vaccine-review-very-rare-cases-unusual-blood-clots- continues.
  6. Cases were reported by EudraVigilance. COVID -19 Vaccine AstraZeneca: PRAC is investigating cases of thromboembolic events – the benefits of the vaccine now outweigh the risks – Update. (March 11, 2021). European Medical Agency. Accessed April 2, 2021. Retrieved from https://www.ema.europa.eu/en/news/covid-19-vaccine-astrazeneca-prac-investigating-cases-thromboembolic-events-vaccines-benefits.
  7. The primary analysis of AZD1222 US Phase III confirmed safety and efficacy. (Mar 25 2021). AstraZeneca. Accessed April 3, 2021. Retrieved from https://www.astrazeneca.com/media-centre/press-releases/2021/azd1222-us-phase-iii-primary-analysis-confirms-safety-and- efficacy. html
  8. Miller, A. (Mar. 29, 2021). Why did Canada suspend the use of the AstraZeneca vaccine in people under 55 years of age. CBC news. Accessed April 2, 2021. Retrieved from https://www.cbc.ca/news/health/canada-suspends-astrazeneca-vaccine-covid-19-1.5968657.
  9. Image by MasterTux from Pixabay





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