The results are in from the CDC’s 2021 data on cases and deaths from COVID-19 by age group and vaccination status. I’m sure all you’ve heard from any mainstream media outlet and government entity is how “safe and effective” are the three American manufactured vaccines. The CDC’s data offers an opportunity to take a substantial amount of information, hopefully collected in a reliable and uniform way, and actually evaluate some aspects of safety and effectiveness. There’s enough to critically interrogate, but this post will go over what in the data supports the benefit of vaccination against COVID-19.
I’m starting out with this because critiques of the vaccine or vaccination policies are often met with lazy characterizations as anti-scientific, offering an easy dodge to confronting the material of the critique. This is the dismantling of any accusation that future discussions are coming from a mind unaware of the quantifiable benefits of the vaccine. You may find below all the good things about the vaccine that we can extrapolate from the CDC’s data, in three main points.
The footnote to all of this is the limitations of the dataset in ruling in or out long term benefits or consequences. All of these benefits are focused tightly around the end points of case rates, mortality rates (both measured in per 100,000 terms so that the figures aren’t ridiculously small), and case fatality ratios (the likelihood of dying if you have a symptomatic infection – more on that below) and segmenting these outcomes by age. Age is a critical segment – we knew since the beginning of the pandemic that the risk profile for hospitalization was age dependent – but it doesn’t tell us everything. This dataset doesn’t tell us anything about patient conditions, nor about events after case detection or vaccination beyond deaths.
What’s the benefit of getting the COVID-19 vaccines?
1) Mortality rates are lower for vaccinated Americans
Unvaccinated Americans in 2021 died presumably from COVID-19 at a rate of 9.6 per 100,000 unvaccinated Americans. Expressed as a percentage this means that 0.0096% of unvaccinated Americans died in 2021. That is over nine times greater than the percentage of vaccinated Americans, 0.001%. This is undeniably a statistically significant reduction in mortality rates, although the practical lethality of COVID-19 for Americans, unvaccinated or not, is obviously debatable.
Another practical area of concern: Americans on average tested positive for COVID-19 in 2021 at an average rate of 207 per 100,000k Americans, or 0.2%. Presumably deaths are preceded by cases, detected or not – although case detection rates are likely positively correlated with case severity. If so, it may be more important to know how fatal cases are for Americans, especially by vaccination status.
2) Cases are less lethal for vaccinated Americans
According to the University of North Carolina’s Gillings School of Global Public Health the Case Fatality Ratio is the, “proportion of people recorded as confirmed COVID-19 cases who die from COVID-19.” It can, “be approximated by dividing the number of deaths by the number of confirmed cases.” The Case Fatality Ratio is useful because risks accrue to people exposed to them. On the other hand mortality rates, in application to contagious diseases, inevitably include people without meaningful exposure to the disease.
How lethal was COVID-19 to Americans exposed in 2021? Of unvaccinated Americans likely around 3.4% of those with a symptomatic case of COVID died from it last year, compared to 1.7% of vaccinated Americans. I use that language because the denominator is arguably a flawed one since asymptomatic infection has been found to be prevalent. In that case we can really only discuss the CFR in terms of those sick enough to seek out testing, with some unknown distribution of people caught up in regular testing who were positive but asymptomatic.
For what it’s worth, case rates were also lower among the vaccinated. This is possibly an indication of the case severity reduction as the COVID-19 vaccines do not provide sterilizing immunity..
At this point, measuring cases to the best extent we can now, the vaccines seem to significantly reduce case fatality. But deaths are also concentrated among those over the age of 65 regardless of vaccination status. Do the vaccines still significantly reduce your chance of dying from a symptomatic case even if you’re young?
3) Both of the above are true for all ages
Whether we’re talking about mortality rates or case fatality ratios, vaccines demonstrated significant protection across age groups. This is especially relevant for those over 65: vaccination arguably makes exposure to a relatively dangerous infection arguably safer than everyday activities like driving a car.
Of course some of that protection is hard to see on these graphs for some age groups. And indeed, case fatality is so low for 12-17 year olds in general that their difference by vaccination status was barely statistically detectable.
##
## Paired t-test
##
## data: subset(unvaxcasefatalityratio, Age.group == "12-17")$Case.fatality.ratio and subset(vaxcasefatalityratio, Age.group == "12-17")$Case.fatality.ratio
## t = 2.9534, df = 34, p-value = 0.005666
## alternative hypothesis: true difference in means is not equal to 0
## 95 percent confidence interval:
## 4.301357e-05 2.327967e-04
## sample estimates:
## mean of the differences
## 0.0001379051Great with that out of the way I can hopefully safely say there’s a lot to be critical and curious about from this data too, particularly regarding our public health tactics and the vaccines from a product safety standpoint. For example, why is Moderna’s case fatality ratio so much higher than other vaccines? Why is J&J’s Janssen vaccine performing so poorly in terms of mortality rates?
You can find my main analysis of the CDC’s COVID-19 Case and Deaths here. And the code behind this analysis is on my GitHub here.