Oxford/AstraZenecca COVID-19 Vaccine (AZD1222)
Author: Valerie Ulai
Covid-19 the global pandemic has already caused the loss of hundreds of thousands of lives and disrupted the lives of billions more [1]. To reduce the tragic loss of life and helping get the pandemic under control, an introduction of Covid-19 vaccine is made [1].
Vaccines work by training and preparing the body’s natural defenses-the immune system- to recognize and fight off the viruses and bacteria they target [2]. After vaccination, if the body is later exposed to those disease-causing germs, the body is immediately ready to destroy them, preventing illness [2].
The WHO strategic Advisory Group of Experts on Immunization (SAGE) has issued interim recommendations for use of the Oxford/AstraZeneca COVID-19 VACCINE (AZD1222). Two versions of the vaccine-produced by AstraZeneca-SKBio (republic of korea) and the serum institute India-have been listed for emergency use by WHO [3]. When the vaccine underwent SAGE consideration, it had undergone review by the European Medicines Agency (EMA) [3]. The EMA has thoroughly assessed the data on the quality, safety and efficacy of the vaccine and has recommended granting a conditional marketing authorization for people aged 18 and above [3].
While vaccine supplies are limited, it is recommended that priority be given to health workers at high risk of exposure and older people, including those aged 65 years and above [3]. It is also recommended for people with comorbidities that have been identified as increasing the risk of severe Covid 19, including obesity, cardiovascular disease, respiratory disease and diabetes [3]. For HIV and pregnant patients, they may be vaccinated if they are part of the group recommended for vaccination and if the benefits outweighs the potential vaccine risk of a pregnant woman [3]. However, further studies are required to assess vaccine safety in immunocompromised people and pregnancy. The vaccine is not recommended for people with a history of severe allergic reaction to any component of the vaccine and persons younger than 18 years of age pending the results of further studies [3].
Furthermore, the recommended dosage of this vaccine is two does given intramuscularly (0.5ml each) with an interval of 8 to 12 weeks [3]. Additional research is needed to understand longer-term potential protection after a single dose [3]. The AZD1222 vaccine against covid-19 has efficacy of 63.09% against symptomatic SARS-CoV-2 infection [3]. Longer dose interval within the 8 to 12 weeks range are associated with greater vaccine efficacy [3]. SAGE has reviewed all available data on the performance of the vaccine in the settings of variant of concern and recommends the use of the vaccine according to the WHO prioritization roadmap, even if virus variants are present in a country [3]. However, each country should assess its risks and benefits taking into consideration each of their epidemiological situation [3].
The introduction of the vaccine will prevent the loss of US$375 billion to the global economy every month [4]. Also, global equitable access to a vaccine, particularly protecting health care workers and those most-at risk is the only way to mitigate the public health and economic impact of the pandemic [1]. The vaccine was praised for its cost-effectiveness and its easy-to-store advantages as well [4].
In contrast, recent cases of blood cloths linked to the vaccine in different countries have led to doubts about its safety [4]. Hence some countries have suspended their vaccination [4]. Recently, researchers at the Greifswald teaching hospital in northern Germany said on Friday 12th March that they have discovered the cause of the unusual blood clot problems found in some recipients of the AstraZeneca coronavirus vaccine [4]. The discovery means that targeted treatment can be developed to avoid serious problems [4]. Researchers have emphasized that treatment would only be possible in patients after blood clots appear, rather than as a preventative treatment to stop a thromboembolic event [4]. WHO release a statement stating that vaccination against COVID-19 will not reduce illness or deaths from other causes and thromboembolic events are known to occur frequently in general [4]. In this time WHO considers the benefits of the AstraZeneca vaccine to outweigh its risks and recommends that vaccines continues [4]. WHO is in regular contact with the European medicines agency and regulators around the world for the latest information on COVID-19 vaccine safety and will immediately communicate the findings to the public [4].
In conclusion, safe and effective vaccines will be a gamechanger. But for the foreseeable future we must continue wearing masks, physical distancing, good ventilation and avoiding crowds. Being vaccinated does not mean that we can throw caution to the wind and put ourselves and others at risk, particularly because it is still not clear the degree to which the vaccines can protect not only against diseases but also against infection and transmission [2].
Reference:
1. COVAX. With a fast-moving pandemic, no one is safe, unless everyone is safe. Available on https://www.who.int/initiatives/act-accelerator/covax. Cited 25th March 2021
2. COVID-19 vaccines. Available on https://www.who.int/emergencies/diseases/novel-coronavirus-2019/covid-19-vaccines. Cited 25th March 2021
3. WHO statement on AstraZeneca COVID-19 vaccine safety signals. Available on. https://www.who.int/news/item/17-03-2021-who-statement-on-astrazeneca-covid-19-vaccine-safety-signals. Cited 25th March 2021.
4. The facts about AstraZeneca′s COVID-19 vaccine. Available on https://m.dw.com/en/what-you-need-to-know-about-astrazenecas-covid-19-vaccine/a-56537177. Cited 25th March 2021.