There has been much talk and advice about COVID-19 vaccines, but what is it that we really need to know? The following information demystifies the facts.
Key messages
- The Pfizer/Comirnaty and Oxford/AstraZeneca vaccines are safe, efficacious, and effective against SARS-CoV-2 and the SARS-CoV-2 Delta variant particularly following two doses.
- Pfizer/Comirnaty and Oxford/AstraZeneca vaccines reduce risks of transmission, infection, illness, hospitalisation, and death.
- Lack of vaccine uptake puts vulnerable members of the community at risk.
- Benefits associated with COVID-19 vaccine administration (both Pfizer/Comirnaty and Oxford/AstraZeneca) outweigh the very small but potential risks of serious adverse reactions for most people.
- Severe reactions to Pfizer/Comirnaty and Oxford/AstraZeneca COVID-19 vaccines are extremely rare.
- Most reactions to COVID-19 vaccines are mild, temporary, and typical for all vaccines.
- The development of blood clots (thrombosis and thrombocytopenia/ TTS) following administration of the Oxford/AstraZeneca vaccine is extremely rare (around 2.6 cases per 100,000 among people aged under 50 and 1.6 per 100,000 among people aged 50 and older).
- It is important that all nurses, midwives, and personal care workers receive COVID-19 vaccines (either Pfizer/Comirnaty and Oxford/AstraZeneca) if they can.
The AstraZeneca vaccine is listed by the Australian Therapeutic Goods Administration (TGA) as safe, effective, and efficacious for protecting people aged 18 years and older against the risk of developing severe SARS-CoV-2/COVID-19 infection.[1] The vaccine has also been found to offer a similar degree of protection from recent COVID-19 variants as the original virus,[2] including the ‘Delta’ variant now emerging in outbreaks in Australia and around the world.[3],[4],[5] The safety and efficacy of vaccines is determined through ongoing analysis of clinical trials, international collaboration, and advice from the Advisory Committee on Vaccines (ACV).[6],[7]
Both COVID-19 vaccines in Australia are effective and safe for the vast majority of recipients and also offer similar levels of protection against the new Delta variant.5, [8], [9] For most people, the benefits of receiving the COVID-19 vaccines outweigh the very remote chance of experiencing an adverse reaction. As the Australian COVID-19 vaccine rollout continues, it is important that nurses, midwives, and personal care workers get vaccinated if they can.
Around the world and in Australia, very rare occurrences of blood clots with low platelet counts (thrombosis with thrombocytopenia/ TTS) have been reported following Oxford/AstraZeneca administration.[10],[11],[12],[13],[14] In Australia, there have been 37 confirmed, 23 probable cases, and two fatal cases of TTS following over 2.5 million doses given.[15] Although estimates of risk based on small numbers of cases are imprecise, the risk of TTS is estimated in Australia at around 3.1 per 100,000 in those <50 years and 1.8 per 100,000 in those ≥50 years.33
For further details and references to the available evidence please see below:
- COVID-19 vaccine effectiveness, efficacy, and safety
- The COVID-19 Delta variant: vaccines and what we already know can protect us
References
[1] Australian Therapeutic Goods Administration (TGA). 2021. COVID-19 vaccine: AstraZeneca ChAdOx1-S – 26 March 2021 [Online]. Australian Government Department of Health. Available: https://www.tga.gov.au/covid-19-vaccine-astrazeneca-chadox1-s (Accessed 1 July 2021).
[2] Voysey M, Clemens SAC, Madhi SA, et al. 2021. Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) against SARS-CoV-2: an interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK. The Lancet 2021; 397(10269): 99-111.
[3] Bernal JL et al. 2021. Effectiveness of COVID-19 vaccines against the B.1.617.2 variant [Pre-Print Online]. MedRxiv. 2021.05.22.21257658. Available: https://doi.org/10.1101/2021.05.22.21257658 (Accessed 30 June 2021).
[4] Public Health England. 2021. Public Health England monitoring of the effectiveness of covid-19 vaccination – 26 May 2021 [Online]. London: United Kingdom Government. Available: https://www.gov.uk/government/publications/phe-monitoring-of-the-effectiveness-of-covid-19-vaccination. (Accessed 30 June 2021).
[5] Stowe et al. 2021. Effectiveness of COVID-19 vaccines against hospital admission with the Delta (B.1.617.2) variant [Online]. London: Public Health England. Available: https://khub.net/web/phe-national/public-library/-/document_library/v2WsRK3ZlEig/view_file/479607329?_com_liferay_document_library_web_portlet_DLPortlet_INSTANCE_v2WsRK3ZlEig_redirect=https://khub.net:443/web/phe-national/public-library/-/document_library/v2WsRK3ZlEig/view/479607266 (Accessed 30 June 2021).
[6] Australian Therapeutic Goods Administration (TGA). 2021. COVID-19 vaccines [Online]. 2021. https://www.tga.gov.au/covid-19-vaccines (Accessed 30 June 2021).
[7] Australian Government Department of Health. 2021. Australian COVID-19 Vaccination Policy 2020 [Online]. Australian Government Department of Health. Available: https://www.health.gov.au/resources/publications/australian-covid-19-vaccination-policy (Accessed 30 June 2021).
[8] Public Health England. 2021. Public Health England monitoring of the effectiveness of covid-19 vaccination – 26 May 2021 [Online]. London: United Kingdom Government. Available: https://www.gov.uk/government/publications/phe-monitoring-of-the-effectiveness-of-covid-19-vaccination. (Accessed 30 June 2021).
[9] Lopez Bernal J, Andrews N, Gower C. et al. 2021. Effectiveness of COVID-19 vaccines against the B.1.617.2 variant [Pre-Print Online]. MedRxiv. 2021.05.22.21257658. Available: https://doi.org/10.1101/2021.05.22.21257658 (Accessed 1 July 2021).
[10] Greinacher A, Thiele T, Warkentin TE, Weisser K, Kyrle PA, Eichinger S. Thrombotic Thrombocytopenia after ChAdOx1 nCov-19 Vaccination. New England Journal of Medicine 2021.
[11] Schultz NH, Sørvoll IH, Michelsen AE, et al. 2021. Thrombosis and Thrombocytopenia after ChAdOx1 nCoV-19 Vaccination. New England Journal of Medicine 2021;384:2092-2101
[12] Cines DB, Bussel JB. 2021. SARS-CoV-2 Vaccine–Induced Immune Thrombotic Thrombocytopenia. New England Journal of Medicine 2021;384:2254-2256
[13] Østergaard SD, Schmidt M, Horváth-Puhó E, Thomsen RW, Sørensen HT. 2021. Thromboembolism and the Oxford–AstraZeneca COVID-19 vaccine: side-effect or coincidence? The Lancet 2021; 397(10283): 1441-3.
[14] Scully M, Singh D, Lown R, et al. 2021. Pathologic Antibodies to Platelet Factor 4 after ChAdOx1 nCoV-19 Vaccination. New England Journal of Medicine 2021;384:2202-2211
[15] Australian Technical Advisory Group on Immunisation (ATAGI). 2021. ATAGI update following weekly COVID-19 meeting – 9 June 2021 [Online]. Australian Government Department of Health. Available: https://www.health.gov.au/news/atagi-update-following-weekly-covid-19-meeting-9-june-2021 (Accessed 30 June 2021).
Author
Micah DJ Peters PhD works at the the National Policy Research Unit (Federal Office), Australian Nursing and Midwifery Federation (ANMF) and the University of South Australia, Clinical and Health Sciences, Rosemary Bryant AO Research Centre
