Risk Analysis of the Moderna and Pfizer Vaccines, part 5

Risk of non-fatal, serious side effects from Covid

When most people claim that the vaccine is more dangerous than the disease it is protecting you from, they will typically discuss only the fatality rate of the disease.  This rate has been very much discussed and has a lot of literature around it, so this is excusable.  However, while the rate of serious non-fatal side effects from Covid is less well discussed, it certainly can not be neglected.

For one thing, even if we didn't have some hard data on nasty but non-fatal effects from Covid, there is a lot of inherent plausibility to this sort of stuff happening with Covid that is not true of the vaccine.  Aside from allergic reactions (which can happen because of any random type of foreign material you inject into the body if your immune system happens to take a disliking to it), there isn't a readily available mechanism from the vaccine that would explain bad reactions.  Everything about the vaccine was chosen because it was seen as harmless or helpful.  On the other hand, the virus (as we have already seen) attacks any organism in the body containing cells with ACE2 receptors.  This includes vital organisms made up of cells that do not regenerate over time (neurons) or which barely regenerate over time (heart tissue).  The potential for long-term damage to the system from Covid is therefore obvious.

What effects have already been seen?

This Mayo Clinic has a good summary of lingering / long-term effects here. Here are the things we have definitely seen:

• Fatigue
• Shortness of breath
• Cough
• Joint pain
• Chest pain
• Muscle pain or headache
• Fast or pounding heartbeat
• Loss of smell or taste
• Memory, concentration or sleep problems
• Rash or hair loss
• Heart tissue damage
• Lung scarring
• Strokes (which have follow-on long-term effects)
• Guillain-Barre syndrome

Problems that are represented as possible, but not seen for sure yet:

• Chronic fatigue syndrome (deduced as possible because SARS CoV 1 causes it)
• Parkinson and Alzheimer's disease (the article says Covid "may" increase the likelihood of these)
• Long-term leg, liver, or kidney damage due to blood clotting

What are the frequencies of these effects?

It's obvious from an initial searching around and reading that we really need more studies on this.  There's a lot of data from the field, but it's a lot harder to parse and evaluate data from the field than from studies that are set up ahead of time to give us specific answers.  Let's try to find current "best guesses" and derive some risk numbers from them.  I'm going to focus specifically on two of the most concerning known issues: heart and brain problems.

Heart Problems

Here is a summary of some recent thinking on Covid-19 and heart problems.  And here is another study pointing to high levels of heart damage in Covid patients.  Here are some key facts:

• In a study of people who recovered--some months prior--from Covid (2/3 had a mild form and recovered at home and 1/3 had been hospitalized), 78% showed signs of heart damage and 60% proved to have continuing cardiac inflammation.  This study of 100 people has some possible selection bias in that there were a few people in the study who were having continuing symptoms and may have therefore self-selected for the study to find out what was going wrong.
• Post-mortem examination of 39 people who died from Covid showed 41% of them had significant infection in the heart even though they had not been diagnosed with any heart-related issues before they passed away.
• In another study, about a quarter of those hospitalized with Covid "experienced myocardial injury".  This may have been only the most obvious patients, however, as this result was from a retrospective study and therefore was only looking for patients diagnosed with these issues.  The median age for this study was 49 years old.

So we see a high percentage of issues here, frequently not obvious and therefore probably underdiagnosed, and not limited to either the most severe cases or the elderly.

On this basis, I am going to assign a relatively high risk to this factor.  I'll put this at a risk of 25% of a serious problem if you are actually diagnosed with Covid and 10% if you are one of the "invisible 66%".

Nervous System / Brain Problems

Here is a decent summary of the uncertain state of affairs regarding brain damage from Covid from Nature.  It only vaguely guesses at prevalence of nervous system issues by comparing with other coronaviruses: 0.04% for SARS and 0.2% for MERS.  This article, on the other hand, states that about a third of Covid patients will experience some neurological issues.  Probably the discrepancy is due to the surprising and not-very-well-understood symptom of anosmia, which turns out to be super-common in Covid for some reason.

This meta-study analysis is the best information I have found so far, combining multiple studies that covered a total of a bit over 11,000 patients.  If we restrict ourselves to looking at the more serious neurological problems, we find a 3% chance of acute cerebrovascular disease and a 2% chance of impaired consciousness.  I am therefore going to go with a 5% chance of serious nervous system problem.  To account for the fact that these studies were probably only looking at diagnosed cases, we will apply this only to the 33% diagnosed cases of Covid.

What percentage of these effects will be permanent / long term?

This is obviously as-yet unknown, since we don't have long-term data for Covid yet.  Both cardiac tissue and nerve cells, though, essentially do not regenerate (cardiac tissue does so very slightly, but unless you're quote young, you can count on the damage being roughly permanent).  We know for certain that some of these issues will be permanent, because we have seen irrecoverable tissue scarring and cell loss in some people.  So it is very difficult to discount this as a risk.

"Long hauler" Covid (Covid that just lingers and lingers and takes forever to go away) has been estimated to happen for about 10% of Covid patients, so this may give us some ballpark figure for how often Covid symptoms will be long term.

Using this as a guide to rough order of magnitude, but decreasing it by one order of magnitude to translate "months" to "years", I'm therefore going to put the risk of this heart or nervous system damage being long term at 1 in 100 if it happens.

What about as-yet unknown long term effects?

With the vaccine, I answered this question by looking at a survey of vaccines in the past that had proven to have unintended side effects, and picked the very most dangerous one I could find as a baseline.  Let's do a similar exercise here, though I will instead pick the most similar virus we know of rather than the most dangerous one. 

For another coronavirus, SARS, there was a 3.6% chance of serious long term lung damage many years after recovery.  Now, SARS had a fatality rate roughly 10 times that of Covid.  So then I think it's fair to give Covid a 0.36% chance of having some serious long-term issue for people beyond just the heart and brain issues I've already discussed.  We'll again apply this risk only to the 33% of diagnosed individuals.

I think this is fair, given just how many different systems Covid can attack.  There are many, many plausible ways that Covid could create serious long term issues that might be overlooked currently.  Furthermore, there are some risks here that we haven't even considered yet, because they are only indirectly linked to the virus itself.  For example, supposing you are hospitalized with Covid.  One thing you can expect to happen is that a bunch of drugs will be given to you.  If you are concerned with possible unknown side effects of the Covid vaccine, shouldn't you also be concerned with possible unknown side effects of all the drugs they will give you to treat your Covid, should it come to that?  This has been known to kill at least one woman, and I'm sure many others as well.

This starts getting really hard to quantify, so I'm just going to roll that type of risk into my 0.36% risk here, which is a guestimate anyway.