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Comment by aazaa | Hacker News Reader

> According to the epidemiologist, the Moderna vaccine has for the past two months been used almost exclusively here for stimulation vaccinations after the Janssen vaccine and after two-dose vaccinations for the elderly and immunocompromised. Very few individuals are said to have received the second dose of the basic vaccine that started with Moderna.

Assuming the translation is correct, this could be a problem in itself. I'm unaware of a single study on the safety or efficacy of mixing vaccine types like this.

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I'm reading between the lines here, but I'm speculating this is the situation:

-Iceland has high vaccination rates, including many people who already got both doses of Moderna vaccines several months ago

-It is too early for standard booster shots with Moderna based on medical guidelines

-Many people were originally vaccinated with other brands (J&J/Jannsen, Pfizer) which have been shown to be less effective than Moderna long-term

-Therefore, many people are "cross-vaccinating" by trying to supplement their existing vaccination with Moderna, which they view as superior

-Because of this, most/all Moderna vaccination shots performed in the last 2 months are from people with other vaccines originally -- in other words, they are only being given in ways that are not within current medical guidelines, and in a manner that has not been sufficiently studied for safety and efficacy.

If this is close enough to represent the situation, then I can see why they might decide the best move overall for public health is to halt use of Moderna, at least for now. Maybe with tighter controls, or over the coming months when there will be higher demand for prescribed Moderna boosters, then it will make sense to bring it back.

I think you are missing the point.

There is a definite connection between pericarditis & myocarditis with the 2 shot vaccines. It is most pronounced with 2nd shots, with the ages of 13-23, particularly for young me, according to VAERS data [1]. Now, I don't know that they know why yet though.

This is similar to the AZN/J&J thrombotic thrombocytopenia syndrome seen in a fairly small group of young women in Europe. While the data on that did indicate it is sometimes not related to a known issue, it is also worsens pre-existing platelet issues, meaning it should likely be contraindicated for a select group of PTs already on thinners or coagulants.

[1] https://openvaers.com/covid-data/myo-pericarditis

The part that confuses me the most is that the two 'vaccine side effects' in question are the swelling of muscles in or around the heart... But side effects of (even mild[1]) COVID infections include _damage_ to muscles in or around the heart.

It seems like halting the use of a flu vaccine because of the flu vaccine causing flu-like symptoms.

[1]https://www.mayoclinic.org/diseases-conditions/coronavirus/i...

In Iceland 95% of the most at-risk over 60 year olds are fully vaccinated and over 90% of everyone over 16 is fully or partially vaccinated. Four people total have died of COVID-19 in Iceland since the beginning of the 2021, around 1/100,000.

The evidence for negative vaccine side effects also suggests they're most prevalent in the younger, healthier population least at risk from COVID, who are also the vast majority of the few remaining Icelanders not fully vaccinated.

Given all that, when considering the potential risk/benefit of offering Pfizer and Moderna or just Pfizer, the expected upside of continuing to offer Moderna if they have any reason for concern is very small indeed.

An important note about those deaths is that at least two of them were tourists. With Iceland's small population (370K) and high number of tourist (though just 340K Jan-Aug 2021, far from the 2 million annually in recent years) many of the metrics for Covid-19 have been skewed (tourists are at least 10% of hospitalizations etc.)

Pericarditis & myocarditis are actually side effects of other vaccines too.

The difference in this case is much higher rates of peri/myo, and also, a larger amount of individuals receiving vaccinations, and, at younger ages.

I think you mean COVID-like symptoms.

> I'm unaware of a single study on the safety or efficacy of mixing vaccine types like this.

The Com-Cov study:

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3874014

In Canada it's common place and there have been no issues that pertain to mixing.

I think there's like a half-dozen countries doing heterologous vaccination regimens. Here's a Wikipedia link about it https://en.m.wikipedia.org/wiki/COVID-19_vaccine_clinical_re...

The mixing makes it harder to get good data, but given the mechanism of action of the vaccine, it seems unlikely that something like myocarditis is purely a result of mixed vaccines. Unlikely enough that it's probably worth pausing the offending vaccine if the risk is higher than the COVID risk.

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