Vaccine myocarditis risk reaches 1 in 10,000 for adolescent boys

Matt Woodley

7/12/2021 5:11:19 PM

But while the rate of Pfizer-related myocarditis continues to increase in males aged 12–17, research cited by the TGA indicates the risk is still dwarfed by the threat COVID-19 poses to this cohort.

Moderna and Pfizer vials.
The current overall estimated rates for the entire population of myocarditis following vaccination are similar for Pfizer or Moderna. (Images: AAP)

The latest Therapeutic Goods Administration (TGA) COVID-19 vaccine weekly safety report shows myocarditis is occurring at a rate of 10.6 cases per 100,000 second doses in males aged 12–17.
The new figures are an increase on those produced two weeks prior, in which the rate was only 8.5 cases per 100,000 second doses, while the overall second dose risk has also grown slightly.
However, research cited by the TGA suggests the risk–benefit profile still supports vaccinating this group. While yet to be peer-reviewed, it indicates that myocarditis occurs at a rate of 87.6 cases per 100,000 COVID-positive males aged 12–17 (Wilson score interval 402–1911 cases per 100,000).

Rates of myocarditis cases following Pfizer

Age (years) All doses Second doses
  Rate per 100,000 doses Rate per 100,000 doses
Male Female Male Female
12–17 6.8 1.4 10.6 2.4
18–29 3.5 1.2 5.7 1.8
30–39 1.4 0.6 1.4 0.5
40–49 0.7 0.6 1.0 0.9
50–59 0.4 0.3 0.1 0.4
60–69 0 0.3 0 0
70+ 0 0.2 0 0
All ages 2.1 0.8 3.0 1.0
The TGA also updated the total number of reported cases of suspected myocarditis in Australia following vaccination to 730 – an increase of 138 over the past two weeks.
Meanwhile, 46 cases were deemed ‘likely myocarditis’ in the past fortnight, taking the overall total to 375 – 114 of whom were teenagers aged 12–17.
Moderna vs Pfizer
According to the TGA, the current overall estimated rates for the entire population of myocarditis for Pfizer and Moderna are similar – 1.4 cases per 100,000 Pfizer doses versus 1.8 cases per 100,000 Moderna doses.
However, statistical analysis shows that there is more uncertainty around the reporting rate for Moderna (likely to be between 1.2 and 2.5 cases per 100,000 doses) than for Pfizer (likely to be between 1.3 and 1.6 cases per 100,000 doses).
‘Because the number of cases of myocarditis reported after Moderna in Australia is small, we are not yet able to calculate reliable reporting rates for it or to see any difference in risk between the two vaccines,’ the TGA stated.
‘In some countries, higher rates of myocarditis and pericarditis have been reported with Moderna than with Pfizer.’
Thrombosis with thrombocytopaenia syndrome
Australia has recorded 166 cases of thrombosis with thrombocytopaenia syndrome (TTS) from about 13.5 million administered AstraZeneca doses. Of these, 144 (82 confirmed, 62 probable) related to a first dose, and 22 cases following a second dose (6 confirmed, 16 probable).
These figures include two new cases of TTS reported this week, an 80-year-old man from Victoria (following a first dose) and a 62-year-old man from NSW (following a second dose).
TTS occurs in Australia at a rate of about 2 out of every 100,000 people after a first dose, and 0.3 out of every 100,000 people after a second dose. The overall chance of death is less than one in a million.
Time to onset, treatment and outcomes for TTS cases
    First dose Second dose
Median time to onset/diagnosis  Median (range) 13 days (1–94) 11 days (2–69)
Treated in ICU At any point 47 1
  Currently 0 0
Outcome Discharged 133 22
  In hospital 2 0
  Fatal 8 0
Guillain-Barre Syndrome
The TGA has received 156 reports of suspected Guillain-Barre Syndrome (GBS) occurring after vaccination with AstraZeneca. However, some suspected cases may not be related to vaccination, as GBS can occur after common viral infections and some types of gastroenteritis.
GBS has been reported in about one in every 100,000 people following vaccination with AstraZeneca.
From the beginning of the vaccine rollout up until 28 November, more than 39.1 million doses of COVID-19 vaccines have been given in Australia, including 24.4 million doses of Pfizer, 13.5 million doses of AstraZeneca, and 1.2 million Moderna doses.
A total of nine people are confirmed to have died as a direct result of vaccination against COVID-19 (0.00002%).
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AstraZeneca COVID-19 Guillain-Barre Syndrome Moderna mRNA myocarditis Pfizer TGA TTS

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Dr Ian   8/12/2021 10:37:22 AM

Would the protein derived vaccines such as Novovax have less of these adverse reactions ?
How far are they from approval in Australia ?
While myocarditis resolves after time there is going to be a risk for the next dose so we will need the protein based vaccines .

Dr Simon John Pilbrow   8/12/2021 12:13:36 PM

There is growing evidence that systemic reactions to vaxes (e.g TTS with AZ and myopericarditis with mRNA vaxes) is likely from inadvertent intra-VASCULAR injection of vaccines, when given by IM route. WHO guidelines on vaccine administration have in recent years indicated that aspirating before vaccinating is unnecessary. We see endless depictions on TV of people being jabbed by 2-step method of "insert, inject". When I was trained, no matter what was injected (IM drug, IM vax, SC, intra-artic, we were always to ASPIRATE before injecting. 3 steps: insert needle, aspirate to make sure you're not in a vessel, then inject. "Insert, aspirate, inject". This quick, 1-sec, safety step ensures we don't inject directly into vessel. IM vaxes (antigen) should go into muscle for gradual uptake by lymphatics. Ultimately Abs circulate in the blood, but antigen must not go directly into bloodstream (e.g fit young male, big muscles getting myopericarditis). Australia should mandate ASPIRATION

Dr Sagir Cinan Ahmed H Alibrahim   8/12/2021 1:02:01 PM

I believe a really good indicator would be the number of hospitalised patients, admission days, any deaths if any from the myocarditis / pericarditis in these young kids

Dr Robert   8/12/2021 1:21:36 PM

"TGA indicates the risk is still dwarfed by the threat COVID-19 poses to this cohort..."
So what is this "dwarfing" threat from COVID that this article references but does not specifiy?

Dr Peter James Strickland   8/12/2021 7:02:58 PM

The chance of myocarditis is minuscule with the mRNA vaccines, and how was it diagnosed in all cases --clinically, or by biopsy of cardiac muscle? What is the myocarditis rate in these youngsters who are unvaccinated, and who get Covid? My understanding is it 6-10 times greater when not vaccinated when they get Covid. We all have to concentrate now in getting Australia back to normal socially for everyone. If anyone is unvaccinated they should now face the consequences of that decision as happens with child-care payments to parents who do not vaccinate their children against all those serious childhood diseases we now have under control. I am from an era who have seen diphtheria, polio, measles, epiglottitis, rubella affected children etc in patients, and there are so-few contraindications to Covid vaccination they are not worth considering --nothing to do human rights, democracy etc with respect to having the vaccines. Just don't support any anti-vaccinaters at all docs!