Should I wait for Pfizer? The case for AstraZeneca - now
Key points
- AstraZeneca (AZ) vaccine is safe and effective.
- The blood clotting condition TTS is rare, occurring in 2-3 per 100,000 people following AZ vaccination.
- Death has occurred in approx. 5% of those who had TTS: a one-in-a-million chance of dying as a result of vaccination.
- COVID-19 kills approximately 3% and causes long-term illness in 10-30% of those who contract it.
- Young people are not exempt.
- The delta variant can emerge anywhere, and vaccination is essential to complement testing, contact tracing and isolation and avoid future lockdowns.
At present there are two COVID-19 vaccines available in Australia, Pfizer and AstraZeneca. Both vaccines are highly effective at preventing serious illness from COVID-19. Both have very rare side effects.
But, as we move into August, with NSW hospitals filling as a result thousands of people infected with COVID 19, and cases emerging in Queensland and elsewhere, there are millions of unused doses of AstraZeneca vaccine sitting in GPs surgeries and vaccination clinics.
In contrast, although supplies of the Pfizer vaccine are gradually increasing, there is insufficient supply to meet demand. Each day, patients ask “Should I wait for a Pfizer or get AstraZeneca now?”
“Should I wait for Pfizer?”
The Delta variant of COVID-19 is highly infectious and appears to infect far more young people than earlier strains.
It causes generally mild disease in vaccinated people, as evidenced in North America, Europe, Britain and vaccinated populations in Asia. Unvaccinated people are virtually the only ones who are dying of this strain.
The disease is rising in Australia. If it escapes into an unvaccinated population, it is possible that we could have thousands of people infected each day. Lockdowns are necessary to limit the number of new cases per day, to enable our health system to manage them, and to minimise the heavy toll COVID would otherwise inflict.
Through a combination of good management and good fortune, Australia has escaped the worst of the global COVID pandemic. But we cannot, as a nation, continue to keep highly infectious strains of COVID at bay without major economic and social costs. Lockdowns alone cannot prevent the spread of the virus and they cause terrible stress and economic hardship.
Get a dose - as soon as possible
Against that background, our strong recommendation to all Australians in an outbreak setting, is to get a first dose of either AstraZeneca or Pfizer vaccine as soon as possible, followed by a second dose as soon as possible.
This is consistent with the latest Australian Technical Advisory Group on Immunisations (ATAGI) advice. Do not wait for the Pfizer vaccine if the AstraZeneca vaccine is available to you now.
AstraZeneca is an excellent vaccine which has already saved millions of lives and will save many more. COVID kills and by the time you, or someone you love, is infected, hospitalised, or in ICU, it is too late.
Addressing AstraZeneca concerns
Concerns in the community about AstraZeneca – and preference for Pfizer – fall into two main categories.
First is safety, and the commonly expressed concern by patients that the AstraZeneca vaccine is not safe because of a link to a rare blood clotting syndrome. Second is efficacy, and the current broadly held perception by patients that Pfizer offers better protection.
In terms of safety, the side effect of the AstraZeneca vaccine, the blood clotting syndrome called thrombosis thrombocytopenia syndrome, or TTS, is rare.
For Australians over age 50, the incidence of TTS following the AstraZeneca vaccine is about one in 50,000. In people aged under 50 years, the incidence is approximately one in 35,000.
Death has occurred in about 5% of people who had TTS: a less than one-in-a-million chance of dying as a result of vaccination.
The low mortality rate compared to other countries is likely due to rapid implementation of improved diagnostic techniques and earlier effective treatments.
Without getting into the minute details of exact risk for people of different ages and acknowledging that risks are slightly higher in younger people, the risk of TTS-caused mortality following vaccination is extremely low – for all age groups. Significantly lower, in fact, than many other well accepted medical interventions and treatments.
The risk of death from COVID-19 in Australia, in contrast, is 1 in 35.
Whilst the risk of death is highest in older age groups, we are now seeing serious illness and death in unvaccinated young patients. The risk, however, is also not all about simple survival. Between 10-30% of people who contract COVID-19 will suffer long term health consequences, the seriousness of which are yet to be fully understood.
The related commonly asked safety question is whether people should have AstraZeneca if they have an existing health condition. See our response below.
Common AstraZeneca questions
Blood clotting experts have identified four rare health conditions which preclude people from vaccination with AstraZeneca:
- a previous history of cerebral venous thrombosis
- abdominal vein thrombosis
- heparin induced thrombocytopenia, or
- antiphospholipid antibody syndrome with blood clots
But for all others (excluding pregnant women) there are no pre-existing health conditions for which there is any evidence which should prevent them from having the AstraZeneca vaccine.
People with a heart condition, diabetes, a history of DVTs, a history of cancer, and many other chronic or severe conditions, can be reassured that based on real world data from the hundreds of millions of AstraZeneca vaccines administered, they face no additional risks.
There is no evidence that the vaccine impacts fertility.
Blood clotting experts have identified four rare health conditions which preclude people from vaccination with AstraZeneca:
- a previous history of cerebral venous thrombosis
- abdominal vein thrombosis
- heparin induced thrombocytopenia, or
- antiphospholipid antibody syndrome with blood clots
But for all others (excluding pregnant women) there are no pre-existing health conditions for which there is any evidence which should prevent them from having AstraZeneca vaccine.
People with a heart condition, diabetes, a history of DVTs, a history of cancer, and many other chronic or severe conditions, can be reassured that based on real world data from the hundreds of millions of AstraZeneca vaccines administered, they face no additional risks.
There is no evidence that the vaccine impacts fertility.
The advice for pregnant women has recently been updated and they are now advised to seek Pfizer vaccine if available.
This is because there is less experience of AstraZeneca in pregnant women, not because there is evidence of increased risk.
On the other hand, if pregnant women become infected with COVID 19, they are more likely than other women of the same age to have severe symptoms and need hospital admission.
In terms of effectiveness in preventing severe disease, both AstraZeneca and Pfizer have similar profiles against Delta.
Delta presents a greater challenge than previous variants of COVID.
People who have one dose of AstraZeneca or Pfizer gain 33 per cent protection against severe disease caused by Delta, less than the protection provided for earlier COVID variants.
Two doses, whether AstraZeneca or Pfizer are, however, both highly protective against severe disease.
Australia is at a critical point in the pandemic. In the past month, we have had COVID lockdowns in NSW, Victoria, Queensland and South Australia. Vaccines offer our only pathway to safeguarding the health of the community, preventing unnecessary deaths, avoiding the financial and health costs of future prolonged lockdowns, and opening our country back to the world.
It is a phenomenal feat of human ingenuity and collaboration to have even one vaccine available so quickly after this new viral challenge arose. To get back to our normal lives, we need to make the most of every vial of every vaccine made – including AstraZeneca.
- Bruce Robinson, Endocrinologist, Royal North Shore Hospital
- Nick Coatsworth, Infectious Disease and Respiratory Physician, Canberra Hospital
- Mark Hertzberg, Haematologist, Prince of Wales Hospital
- Tony Cunningham, Virologist, Westmead Hospital
- Michael Grigg, Vascular Surgeon, Box Hill Hospital
- Vijay Roach, Obstetrician and Gynaecologist, Royal North Shore Hospital
- Tania Sorrell, Infectious Disease Physician, Marie Bashir Institute, University of Sydney
- Bernie Hudson, Infectious Disease Physician, Royal North Shore Hospital
- Steve Hambleton, General Practitioner, Brisbane
- Gemma Figtree, Cardiologist, Royal North Shore Hospital
- Danny Hsu, Haematologist, Liverpool Hospital
- Ian Frazer, Renal Physician, Royal Brisbane Hospital
- Lyn Gilbert, Senior Researcher, Marie Bashir Institute, University of Sydney
- Anthony Holley, Intensive Care Specialist, Royal Brisbane and Women’s Hospital