Ongoing Arizona Research Study Confirms COVID Vaccine Effectiveness

Aug 5, 2021

Vaccines provide a high level of protection against COVID-19. That’s one of the findings of an ongoing research study following health care workers, first responders, and other essential workers in Arizona. KNAU’s Melissa Sevigny spoke with Dr. Jeff Burgess of the University of Arizona Health Sciences about the HEROES study and why the rise of the Delta variant in Arizona is worrisome.

Credit Chris Richards/University of Arizona


Why is it critical to study the COVID vaccine in people who have been vaccinated? We know it works from the clinical trials, right?

When the initial clinical trials are done, that’s done in controlled circumstances. It’s not real world, you might say…. So for example if you’re healthcare worker, you’re getting exposed to your patients. If you’re a first responder, you’ll be exposed to the public and coworkers, and if you’re an essential worker, you’re out there right next to you a lot of people who could giving COVID to you. So it’s important to look at this in these individuals that have a particularly high level of risk of exposure.

What did you find out about breakthrough infections? I mean, how many people who have vaccine are actually getting infected?

The studies that we published on so far are pre-Delta so I think that’s really important. Things have changed a lot. But in the initial phases of the pandemic…. what we found was that if you were vaccinated with one of the messenger RNA vaccines, Pfizer or Moderna, you had a 91% protection against COVID 19. You had only a very small percentage of individuals that got an infection after vaccinated. Those we call breakthrough infections. And what we found was that in those individuals with breakthrough infections, they had shorter illnesses, less severe illnesses, and furthermore, the amount of virus that we could culture from them when they were sick was much lower than in people who got COVID without being vaccinated. They shed the virus for a much shorter period of time. Initially these vaccines were truly wonderful and they had protection very close to that which was shown in the original clinical trials.

As you continue this study, how do you anticipate the Delta variant might change things?

We’re all quite worried about the Delta variant. Now, the good news is the vaccine still provides protection. …. What is different, however, is that if you do get a breakthrough infection with the Delta variant, you, at least from—not from our study but from other studies out there that we’ve heard about so far—it appears that you don’t have a reduction in the amount of virus that’s in you. So you can now pass it on to others, where it was much less likely in the past.

Are you still recruiting for this study?

Yes, we are still recruiting. We have actually just started recruiting youth, that’s kids anywhere from 4 months up to 17 years of age…. We know the older kids are getting vaccinated now, but we anticipate this fall the vaccine will be available also for the younger kids We’ll be able to see whether we have the same level of effectiveness in the vaccine in kids as we’ve being seeing in adults.

Dr. Burgess, thank you so much for speaking with me.

Take care, Melissa, thank you.

Learn more about the study here: https://azheroes.arizona.edu/