Analysis of CDC Data on COVID-19 Case Fatality Rate in Winter 2021-22 by Vaccination Status and Age

 How did vaccines and boosters impact Coronavirus lethality rates in US in Winter 2021-22? 

In this article we took the official data [1] from the Centers for Disease Control and Prevention (CDC) of the United States of America to analyze the effect of vaccination status on lethality rates of COVID-19 in the Omicron Wave between December 2021 and February 2022, this article should be viewed only as a raw Data Analysis exercise without any prior political or medical prejudice, the code has been published on GitHub repository. All analyses were done with Python and the modules pandas and Matplotlib
The Case Fatality Rate (CFR) is defined as the ratio of deaths over cases (Deaths/Cases), indicating the lethality of the disease on the population groups analyzed. The results are the following:

 Fig. 1. CFR for all ages by month, vaccine product and status. The Pfizer vaccine has a greater CFR for people boosted than only with the original two doses,  once boosted the best vaccine to reduce death probability is Jannsen.

Fig. 2. CFR for 12-17 Age Group, there were no recorded fatalities for the boosted.

 Fig. 3. CFR for 18-49 Age Group, lethality reduction is more appreciable than for kids.


Fig. 4. CFR for 50-64 Age Group.

 Fig. 5. CFR for 65+ Age Group.

 Graphically in Figs. 1 to 5 there is an appreciable reduction in lethality for the vaccinated people and more for the boosted people with respect to the unvaccinated group (this analysis would be even more telling if there were data for people who had been previously infected, so as to compare vaccine effectiveness against the natural immunity).We calculated the relative change in CFR for each group to put a number on the observations, and also performed a t-test to determine if the difference between CFR is statistically significant.

Table with the summary of results:

t-Test on CFR by Vax. Status per Age Range in Winter 21-22:
                                     12-17      18-49      50-64        65+
CFR Unvaxxed (%)                    0.0062    0.09501   0.962456   5.779413
CFR Vaxxed (%)                    0.003122   0.027892   0.321796   3.349548
CFR Boosted (%)                        0.0    0.01347     0.1576    1.42223
CFR Reduction Vax-Unvax (%)      49.648033  70.642958  66.565154  42.043468
CFR Reduction Boosted-Unvax (%)      100.0   85.82297  83.625256  75.391441
p-value Vax-Unvax                 0.429324   0.047613   0.056727   0.037261
Significant Vax-Unvax                   No        Yes         No        Yes
p-value Vax-Boosted               0.258723   0.259471    0.20088   0.004133
Significant Vax-Boosted                 No         No         No        Yes


Analysis Code:

GitHub Repository:


[1] Rates of COVID-19 Cases or Deaths by Age Group and Vaccination Status and Booster Dose.

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