Side effects of COVID vaccines: the facts
Every week, the Therapeutic Goods Administration (TGA) releases a summary of all reported adverse events that happen following a COVID-19 vaccination. Along with this, the TGA continuously monitors the administration of medicines and vaccines.
The reports are long and can be very dense, so Cosmos breaks them down into bite-sized pieces.
Report date: 30th September 2021
Total amount of vaccines administered to date: 26.8 million
Pfizer (Comirnaty): 15.1 million
AstraZeneca (Vaxzevria): 11.6 million
Moderna (Spikevax): 36,000
What are some of the most common vaccine side-effects on the list?
We highlighted side-effects some of the most reported side effects following vaccination. The most common side-effects on the list were headache, fever, joint and muscle pain, nausea and chills.
Pfizer (Comirnaty)
In total, there have been 26,921 reports of adverse events following Pfizer, at a rate of 178 reports per 100,000 doses, or 0.2%.
The most common side-effects reported were headache, sore muscles and joints, injection site irritation, nausea, fever, fatigue and chills.
| Reported Event | Total Reports | Reports per 100,000 doses |
|---|---|---|
| Headache | 5927 | 44.5 |
| Myalgia (Muscle pain) | 4692 | 31.1 |
| Pyrexia (Fever) | 3243 | 21.4 |
| Injection site reaction | 3647 | 24.6 |
| Nausea | 3403 | 22.5 |
| Chills | 2324 | 15.3 |
| Arthralgia (joint pain) | 2840 | 18.8 |
| Dizziness | 2122 | 13.6 |
AstraZeneca (Vaxzevria)
There have been 37,049 reports of events following AstraZeneca, at a rate of 3193 reports per 100,000 doses, or 0.32%. Of these, the most common side-effects reported were headache, sore muscles and joints, injection site irritation, nausea, fever, fatigue and chills.
| Reported Event | Total Reports | Reports per 100,000 doses |
|---|---|---|
| Headache | 11557 | 109.6 |
| Myalgia (Muscle pain) | 7722 | 69.6 |
| Pyrexia (Fever) | 7407 | 56.7 |
| Injection site reaction | 4350 | 39.2 |
| Nausea | 4707 | 42.4 |
| Chills | 5525 | 49.8 |
| Arthralgia (joint pain) | 4478 | 40.3 |
| Dizziness | 2771 | 25.0 |
Moderna (Spikevax)
To date, there have been 5 suspected adverse events associated with the Moderna vaccine. The reactions were consistant with common side effects of the previous two vaccines.
How common are severe vaccine side-effects?
Pfizer – Heart inflammation
To date, there have been 850 reports of suspected myocarditis or pericarditis – inflammation of the heart – at a rate of 5.6 per 100,000 doses – or .003%.
Of these, 115 were assessed and deemed likely to be myocarditis, but the assessment does not determine whether it was caused by the vaccine.
These conditions typically occur within 3 days of vaccination, but more so after the second dose. It is more common in younger men or teenaged boys.
While some patients have required hospital treatments, but there have been no reported deaths due to heart inflammation following Pfizer administration.
AstraZeneca – Blood clots
There have been a total of 148 reported cases of thrombocytopenia syndrome (TTS), or blood clots. Of these, 83 were confirmed to have been caused by the vaccine, and 65 were considered probably caused by the vaccine.
Cases were considered probable but not confirmed when the clot occurred more than 50 days after vaccination, after which it becomes difficult to establish a link. These cases will continue to be investigated, and can account for some changes in total confirmed cases.
Despite this, blood clots are very rare.
TTS occurred at a rate of 1.6-3.0 per 100,000 doses, depending on age. The highest rate of incidence (3.0 per 100,000) occurred in people aged 50-59, followed by people above the age of 80 (2.0 per 100,000).
Overall, the reports states that there have been 8 deaths linked to TTS following the first dose of AstraZeneca, at a rate of 0.06 per 100,000 doses.
The chart below shows the age breakdown of TTS occurrence:
| Age | Total cases | Cases per 100,000 doses | Tier 1* cases | Tier 2** cases |
|---|---|---|---|---|
| <30 | 7 | 1.8 | 2 | 3 |
| 30-39 | 5 | 1.8 | 4 | 1 |
| 40-49 | 8 | 1.8 | 6 | 1 |
| 50-59 | 35 | 3.0 | 18 | 11 |
| 60-69 | 35 | 1.6 | 11 | 9 |
| 70-79 | 40 | 2.0 | 10 | 12 |
| 80+ | 18 | 2.0 | 4 | 8 |
| All ages | 148 | 2.0 | 55 | 45 |
Tier 1* = clots in an unusual location (such as the brain or abdomen) and a low platelet count with or without antibodies that activate platelets (anti-PF4 antibodies)
Tier 2** = clots found in common locations (such as the leg or lungs) and a low platelet count and anti-PF4 antibodies
What are the symptoms of blood clot?
TTS typically occurs 3-30 days following vaccination with AstraZeneca, and most commonly presents at 2 weeks. Typical symptoms include persistent headache, blurred vision, drowsiness, chest pain, swelling in the legs and persistent belly pain.
Furthermore, women are more likely to develop a TTS in a problematic area, such as the brain, than men. Because of this more women have died from a TTS.
Worried? Ask your doctor about your risk of vaccine side-effects.
How many people have died from a vaccine in Australia?
According to the report, there have been 9 vaccine-related deaths, all of which occurred after the first AstraZeneca dose. Of these, 8 were cases of thrombocytopenia syndrome (blood clot) and one was a case of immune thrombocytopenia (excessive bleeding due to low platelet count).
This represents a rate of 0.77 deaths per million doses of AstraZeneca, and 0 deaths for Pfizer.
Altogether, there was a total of 516 deaths in vaccinated people within three months of vaccine administration, but after review, only 9 were found to have been likely due to the vaccine.
Consequently, the rest were from unrelated causes and coincidentally happened during the timeframe of three months they were monitored.
Additionally, most of the deaths following vaccination occurred in people over the age of 65.
Why are there so many reports of vaccine side-effects?
The adverse effects following administration include ANY medical event reported. In the extended list, reported events within three months of administration include foot fracture, tongue injury, yeast infection, indifference and impatience, and tinea.
The culmination of all reported incidents inflates the total number, because this is all reported events, not all vaccine-caused events.
Do the benefits of vaccination outweigh the risks of COVID-19?
On September 30, there were 21,428 active COVID-19 cases in in Australia, of which 1,514 were in hospital and 303 were in ICU. This means 7065 people in hospital per 100,000 active cases, and 1104 people in ICU per 100,000 active cases.
In Australia, the deathrate for closed COVID-19 cases (either recovered or died) is approximately 1563 per 100,000, or ~1.5%, although deathrate is directly linked to medical services available, dominant variant, vaccination rates and age.
What are the long-term vaccine side-effects ?
A well-established body of evidence shows that vaccine side-effects present themselves very quickly, typically within 2 months. The TGA monitors for 3 months to be conservative.
The World Health Organisation states that “Severe or long-lasting side effects are extremely rare”.
Need more information?
- A brief history of vaccines
- A letter to my vaccine-hesitant friends
- What does 80% vaccination coverage mean?
- COVID-19 and women
- What’s with COVID-19 “breakthrough infections”?
- How well will our vaccines hold up against Delta?
- COVID-19 vaccines for young children?
- Explainer: Moderna vaccine approved in Australia
- What’s in a COVID vaccine?
Originally published by Cosmos as Worried about COVID vaccine side effects? Here’s what’s happening each week.
Deborah Devis
Deborah Devis is a science journalist at Cosmos. She has a Bachelor of Liberal Arts and Science (Honours) in biology and philosophy from the University of Sydney, and a PhD in plant molecular genetics from the University of Adelaide.
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