CDC study: COVID-19 vaccines remain highly effective, especially against hospitalization and death

We at ADHS are pleased to have contributed to a recent Centers for Disease Control and Prevention (CDC) report offering a new and very useful way to look at the effectiveness of COVID-19 vaccines in light of rare breakthrough cases among the fully vaccinated.

A key takeaway from this report in the CDC’s Morbidity and Mortality Weekly Report: COVID-19 vaccination has continued to provide robust protection against hospitalization and death even after the highly contagious Delta variant became the dominant variant in late June. If you aren’t fully vaccinated and get COVID-19, your risk of being hospitalized or dying is more than 10X higher than that of someone who is fully vaccinated.

Analyzing information from Arizona and 12 other states, the report examines the difference between unvaccinated and fully vaccinated individuals ages 18 and older when it comes to COVID-19 cases, hospitalizations, and deaths. It uses rates of each outcome among each group to develop a ratio of how much more likely one group is to have that outcome. The public health term for this comparison is incidence rate ratio (IRR).

The report also examines these ratios before and after late June, when the highly contagious variant known as Delta became the overwhelmingly dominant COVID-19 variant.

In a nutshell, here’s what it found:

Before late June, those who weren’t fully vaccinated were 11.1 times more likely to get COVID-19 than fully vaccinated individuals. After late June, when Delta was the dominant variant, those who weren’t fully vaccinated were 4.6 times more likely to get COVID-19.
Before late June, those who weren’t fully vaccinated were 13.3 times more likely to be hospitalized than fully vaccinated individuals. After late June, those who weren’t fully vaccinated were 10.4 times more likely to be hospitalized from COVID-19.
Before late June, those who weren’t vaccinated were 16.6 times more likely to die from COVID-19 than those who were fully vaccinated. After late June, they were 11.3 times more likely to die from COVID-19 than those who were fully vaccinated.

If you think that means vaccines aren’t protective, think again. As with the flu vaccine, the COVID-19 vaccines protect against serious illness and death while reducing the transmission of disease. These findings are consistent with other recent studies showing decreased vaccine protection against confirmed COVID-19 infection, when the Delta variant has predominated and immunity from the vaccine may be waning in the population. But they also suggest that vaccines continue to offer stable, strong protection against hospitalization and death.

As with every analysis, there are limitations. But the results are consistent with other studies and what public health has been saying about the continuing effectiveness of the safe, free, and widely available COVID-19 vaccines. They are still achieving their purpose of protecting people against COVID-19, especially severe illness and death .

We strongly urge you to roll up your sleeve and get vaccinated today at one of the hundreds of providers around Arizona. The vaccine is our best line of defense against COVID-19. It protects you, those you love, and your community.

By Jessica Rigler|2021-09-10T12:22:16-07:00September 10th, 2021|Preparedness|Comments Off

About the Author: Jessica Rigler

Jessica Rigler, an Arizona native, began her public health career more than 15 years ago, serving in varied roles with local, state, federal, and international public health agencies. Jessica has been with the Arizona Department of Health Services for over 12 years, supporting evaluation activities with the state immunization program, serving as the state’s first Healthcare Associated Infections Coordinator, and leading the Bureau of Epidemiology and Disease Control. She is currently an Assistant Director overseeing the Division of Public Health Preparedness at ADHS, which spans the areas of Epidemiology and Disease Control, Emergency Medical Services, Public Health Statistics, Public Health Emergency Preparedness and the Arizona State Public Health Laboratory. In recent years, Jessica has worked with the ADHS team to lead critical public health responses including opioids and COVID-19. Jessica holds Bachelor’s degrees in biochemistry and human development from the University of California, San Diego, and a Master’s degree in public health from Emory University. She is a Certified Health Education Specialist and certified in infection control.