An autopsy on 26-year-old man Rory Nairn found he likely died of the heart condition
myocarditis following the Pfizer jab.
Dr Hung, who performed the autopsy, provided risk calculations and reassurances that this event had a "one hundred fold greater chance of death of myocarditis following Covid than following the jab" (NZ Herald, December 24). Some clarification regarding those calculations is required.
• A response has also been published to this article by professors Peter McIntyre and Nikki Turner.
The calculation hinged on the premise that "2 per cent of primary Covid-19 infections lead to death by any complication." That figure refers to Covid's Case Fatality Rate (CFR) - the ratio between confirmed deaths and cases. It doesn't tell us the ratio between confirmed deaths and all people with infections per se. That is, deaths from all infections, including those that are asymptomatic and unreported. That ratio is the Infection Fatality Rate (IFR).
Science to determine the IFR differs according to region and age stratification however there is a general acceptance of values: Previous estimations showed an IFR of 0.05 per cent for those under 70 years, with an average IFR of 0.23 per cent.
The updated average IFR was 0.15 per cent. The most recent estimations, stratified by
age, by the same author, are: 0-19 years 0.0013 per cent, 20-29 years 0.0088 per cent, 30-39 years 0.021 per cent, 40-49 years 0.042 per cent, 50-59 years 0.14 per cent, 60-69 years 0.65 per cent.
One of the features of Covid is its large spectrum of pathogenicity depending on age, comorbidities and other factors. There are infections causing death and complications at one end of the spectrum, and infections that are asymptomatic or mild enough to be inconsequential at the other.
The Dr Hung article effectively left out the latter group by using the CFR instead of the IFR. This resulted in an overestimation of 100,000 New Zealanders dying of Covid including 2500 from Covid-infection-myocarditis.
If the IFR had been used instead, that same calculation would have yielded 7500 Covid deaths including 188 from Covid-infection-myocarditis. As a result, there is not a one hundred fold increased risk in comparison to the vaccine, as claimed, but instead it works out at about a nine fold risk.
It was an honest oversight. However the impact is serious because New Zealanders are anxious about both Covid and vaccines and are making important health decisions based on available information. This includes young men such as Rory Nairn.
Rory was 26 when he died of vaccine-induced-myocarditis. His average chance of myocarditis following vaccination was 0.0012 per cent according to data from Israel quoted by Dr Hung on December 24.
Twenty-four hours later, on December 25, 2021, more data became available. This data was extended and stratified by age and sex so yielded results not in its parent study - it was an important pre-print.
It concluded that there is a similar risk of myocarditis following either vaccination or Covid infection in Rory Nairn's demographic.
The original peer-reviewed study analysing the data was from 42,000,000 cases in the UK and published in the prestigious Nature Medicine. The authors then extended the analysis to provide further age-stratified information. This followed academic pressure and a thirst for more information from the public.
Although the study concluded that myocarditis risk was similar for the vaccine and Covid infection-myocarditis in young men under 40, the raw data showed higher risk after vaccination.
For vaccines, additional myocarditis cases were increased by 0.0012 per cent after shot two and 0.0013 per cent after shot three, compared to Covid-infection-myocarditis additional cases of 0.0007 per cent.
Overall however, the averaged data was consistent with the original study which "demonstrated that across the entire vaccinated population in England, the risk of myocarditis following vaccination was small compared to the risk following a positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test". This is because for all other demographics, except young men, the risk of myocarditis was substantially smaller after vaccination than a Covid infection.
Specifically, the extended-analysis results showed an average of 0.0002 per cent additional myocarditis cases following vaccination compared to 0.003 per cent following Covid.
The study did not discuss the implications of declining vaccine efficacy or the percentage of the population which would eventually to be infected with Covid, both of which complicate the calculation of risk.
Hung assumes that 100 per cent of New Zealand's population will eventually contract Covid with one variant or another. Perhaps this is the subject of a separate commentary.
It's clear we need to scrutinise information, enquire about recent science and continually update ourselves in a world of emerging new uses for technologies. It is imperative that New Zealanders are able to make fully informed choices regarding medical products.
I'm sure New Zealanders join me in expressing our deepest sympathy to Rory's fiance and family. May he rest in peace.
• Amanda Vickers has an honours degree in Physiology and a Bachelor of Veterinary Science degree, now retired.