Impact of COVID Vaccination on COVID Hospitalisations in the USA.
Are they lower as would be expected if the vaccine was effective at reducing serious illness?
Data from The Coronavirus Disease 2019 (COVID-19)-Associated Hospitalization Surveillance Network (COVID-NET), which conducts population-based surveillance for laboratory-confirmed COVID-19-associated hospitalizations in children (persons younger than 18 years) and adults.
The current network covers nearly 100 counties in the 10 Emerging Infections Program (EIP) states (CA, CO, CT, GA, MD, MN, NM, NY, OR, and TN) and four additional states through the Influenza Hospitalization Surveillance Project (IA, MI, OH, and UT).
The network represents approximately 10% of US population (~32 million people).
I have scaled the data up ten-fold to approximate the nationwide picture and plotted the cumulative series broken into three sections:
Pre-vax (Mar 2020 to Oct 2020)
Winter surge (Nov 2020 to Feb 2021)
Post-vax (Mar 2021 to Oct 2021)
In the post-vax period, the fully vaccinated population rose from 5% to 60% so we should observe a related concavity in the slope, as well as a lower overall hospitalisation rate.
I examine this by fitting a simple, linear regression through the pre-vax and post-vax data respectively. Subsequently, we can compare the slopes and also test for concavity (the post-vax slope should curve down and under the linear trend).
In the over 65s, the post-vax hospitalisation rate is 18% lower than pre-vax but does not appear to exhibit any concavity.
In the 18 to 64 year olds, the post-vax hospitalisation rate is 11% higher than before the introduction of the experimental mRNA therapeutic. Inevitably, there is no concavity either.
In the under 18s, the post-vax hospitalisation rate is a massive 74% higher and since the summer, there is apparent convexity rather than concavity.