- #1
- 23,482
- 10,810
- TL;DR Summary
- Are the COVID vaccines substantially different from/inferior to other vaccines in terms of their effectiveness?
Background:
While discussing a moderator action in the private forum a statement was made that points to a potentially fundamental misunderstanding of how vaccines/vaccinations work that may be pervasive regardless of which side is correct. I'm spinning that discussion off and re-starting it here. I'll paraphrase the positions so that the people originally involved can join or decline to participate as they wish. My main objective is to clarify a correct understanding, and in particular have some of our resident subject matter experts confirm what is correct.
Groundrules:
The issue raised, and I'm mostly paraphrasing here, is this:
Most vaccines (e.g. measles, smallpox) have efficacy defined such that (for example) a 95% effective vaccine means that for a group of thoroulghly exposed people, 95% of the vaccinated are "immune" and will not get infected or pass the disease along and 5% might. The protection from infection is all or nothing and whether one can transmit the disease is also all or nothing (the "infected" can, the "not infected" cannot). That's why they don't have resurgences and "breakthrough infections" for most vaccines.
The COVID vaccine is fundamentally qualitatively different from other vaccines in that neither the "immune" nor "unprotected" states of the vaccinated are absolute; the vaccines will not prevent people from getting infected or spreading the disease. And that's why there are breakthrough infections and resurgences of the disease even in heavily vaccinated populations. The example of a similar "different" type of vaccine that isn't "effective" and doesn't provide "immunity" is the flu vaccine. The measles and smallpox vaccines are of the "normal"/effective type.
The CDC was provided as a source for the claim/definitions:
"Historically, the vaccine has been effective in preventing smallpox infection in 95% of those vaccinated"
https://www.cdc.gov/smallpox/vaccine-basics/index.html
My Understanding:
Here's a few sources:
https://en.wikipedia.org/wiki/Vaccine
https://www.health.ny.gov/publications/7022/
https://www.cdc.gov/vaccines/vpd/measles/index.html
https://en.wikipedia.org/wiki/MMR_vaccine#MR_vaccine
https://pubmed.ncbi.nlm.nih.gov/31039835/
The wikipedia describes the purpose of a vaccine to be creating antibodies for the purpose of protecting against disease. While it's tempting to read that or the CDC quote above as binary, my second source provides the same quote with an important qualification:
The measles vaccine program has several of the claimed negative characteristics of the COVID vaccine program; breakthrough cases, variable immunity, inability to prevent the disease in the vaccinated.
What you see with this example is that: high vaccination rate * high vaccine effectiveness * high transmissibility = high potential for resurgence and high fraction of cases amongst the vaccinated. That's what we're seeing with COVID.
A few other thoughts:
The claimant on to say (actually opened with):
When I was a kid, everyone knew this is how vaccines work...
I believe the issue here is two-fold:
While discussing a moderator action in the private forum a statement was made that points to a potentially fundamental misunderstanding of how vaccines/vaccinations work that may be pervasive regardless of which side is correct. I'm spinning that discussion off and re-starting it here. I'll paraphrase the positions so that the people originally involved can join or decline to participate as they wish. My main objective is to clarify a correct understanding, and in particular have some of our resident subject matter experts confirm what is correct.
Groundrules:
- The issue has clear political implications (that's why it was brought up), but we will not be discussing the political implications, only the factual epidemiological aspect.
- Anti-vax misinformation will not be tolerated. To be sure, when discussing what at the start may be a wrong claim there is a risk of "misinformation", but what separates just being wrong from infractionable "misinformation" is the quality of the argument and willingness to accept quality contradicting information. In other words, cite quality sources and interpret them faithfully and you'll be fine. But we'll have a tight leash here.
The issue raised, and I'm mostly paraphrasing here, is this:
Most vaccines (e.g. measles, smallpox) have efficacy defined such that (for example) a 95% effective vaccine means that for a group of thoroulghly exposed people, 95% of the vaccinated are "immune" and will not get infected or pass the disease along and 5% might. The protection from infection is all or nothing and whether one can transmit the disease is also all or nothing (the "infected" can, the "not infected" cannot). That's why they don't have resurgences and "breakthrough infections" for most vaccines.
The COVID vaccine is fundamentally qualitatively different from other vaccines in that neither the "immune" nor "unprotected" states of the vaccinated are absolute; the vaccines will not prevent people from getting infected or spreading the disease. And that's why there are breakthrough infections and resurgences of the disease even in heavily vaccinated populations. The example of a similar "different" type of vaccine that isn't "effective" and doesn't provide "immunity" is the flu vaccine. The measles and smallpox vaccines are of the "normal"/effective type.
The CDC was provided as a source for the claim/definitions:
"Historically, the vaccine has been effective in preventing smallpox infection in 95% of those vaccinated"
https://www.cdc.gov/smallpox/vaccine-basics/index.html
My Understanding:
Here's a few sources:
https://en.wikipedia.org/wiki/Vaccine
https://www.health.ny.gov/publications/7022/
https://www.cdc.gov/vaccines/vpd/measles/index.html
https://en.wikipedia.org/wiki/MMR_vaccine#MR_vaccine
https://pubmed.ncbi.nlm.nih.gov/31039835/
The wikipedia describes the purpose of a vaccine to be creating antibodies for the purpose of protecting against disease. While it's tempting to read that or the CDC quote above as binary, my second source provides the same quote with an important qualification:
It is my contention/claim that the CDC quote is over-simplified due in part to limited testing/tracking. There's some logic that I think should be obvious:Smallpox vaccination provides full immunity for 3 to 5 years and decreasing immunity thereafter. If a person is vaccinated again later, immunity lasts even longer. Historically, the vaccine has been effective in preventing smallpox infection in 95% of those vaccinated... It is important to note, however, that at the time when the smallpox vaccine was used to eradicate the disease, testing was not as advanced or precise as it is today, so there may still be things to learn about the vaccine and its effectiveness and length of protection. [emphasis added]
- When a virus is introduced/attacks, it's a numbers game. The number of virus particles vs the number and strength of antibodies determine how many cells are infected and how fast (or if) the body fights off the attack. There must be an infinitely granular spectrum of potential results. "Infected" and therefore "immune" are not clear-cut/binary states. With better testing and data analysis we can detect the virus in smaller and smaller quanties in people, even if the viral load is so low that they are asymptomatic. 50 years ago these people would have been labeled "not infected", and if vaccinated, counted as "immune". Today, they are asymptomatic infections.
- Vaccine efficacy wanes over time. This is another indication of a spectrum of protection.
This should make clear:In an outbreak of measles in Gothenburg, Sweden, breakthrough infections (i.e. infections in individuals with a history of vaccination) were common... Sixteen of 28 confirmed cases of measles in this outbreak were breakthrough infections... Measles viral load was significantly lower in nasopharyngeal samples from individuals with breakthrough compared with naïve infections... No onward transmission from breakthrough infections was identified. Our results indicate that a high risk of onward transmission is limited to naïve infections.
The measles vaccine program has several of the claimed negative characteristics of the COVID vaccine program; breakthrough cases, variable immunity, inability to prevent the disease in the vaccinated.
What you see with this example is that: high vaccination rate * high vaccine effectiveness * high transmissibility = high potential for resurgence and high fraction of cases amongst the vaccinated. That's what we're seeing with COVID.
A few other thoughts:
- The Delta variant adds another monkey wrench to this. In some ways, it is a separate or secondary pandemic.
- All this is happening *fast* and with extreme data granularity.
The claimant on to say (actually opened with):
When I was a kid, everyone knew this is how vaccines work...
I believe the issue here is two-fold:
- Clipped/concise communication, while efficient, leads people to fill in the gaps or add caveats as needed, leading to an understanding that is overly simplistic or aligned with biases.
- Improved testing and tracking has provided an ability to split the "effectiveness" hair, when it wasn't possible to split it before. In the past, "immune" was considered binary because the data was incapable of showing that it wasn't.
- Is my understanding of how vaccines work correct? or:
- Is there a fundamental qualitative difference between different types of vaccines based on which the COVID vaccines fall into a "substantially not as good" category? Even if it's something I missed/didn't describe properly in the premise?