It’s true that some people have tested positive for the coronavirus even after getting a vaccine, but that is no indication the vaccines don’t work. On the contrary, public health experts say the evidence is overwhelming that the shots dramatically reduce your chances of severe illness and death. “I lose infinitely more sleep over the fact that we have such large numbers of unvaccinated people who are at a tremendous risk of developing severe disease,” Janko Nikolich-Žugich, MD, PhD, an immunologist and professor of medicine at the College of Medicine – Tucson, told NBC News. “We shouldn’t be complacent or cavalier about it, but it pales in comparison to the question of how we get as many people as possible vaccinated.”

Public health experts say the evidence is overwhelming that the shots are doing exactly what they are supposed to do. They dramatically reduce your chances of severe illness and death. “I lose infinitely more sleep over the fact that we have such large numbers of unvaccinated people who are at a tremendous risk of developing severe disease,” Janko Nikolich-Žugich, MD, PhD, an immunologist and professor of medicine at the College of Medicine – Tucson, told NBC News. “We shouldn’t be complacent or cavalier about it, but it pales in comparison to the question of how we get as many people as possible vaccinated.”

The new CDC guidelines recommend a return to indoor masking — this time for vaccinated people as well as the unvaccinated. Saskia Popescu, PhD, MPH, MA, an infectious disease epidemiologist and adjunct professor at the Mel and Enid Zuckerman College of Public Health, discusses the updated guidelines and whether this is an indication of a step backward in terms of curbing the spread of COVID-19.

According to Deepta Bhattacharya, PhD, an immunologist at the College of Medicine – Tucson, the virus must overcome "backup layer after backup layer" of defenses. So even if a virus continues to spread through a person's body, "each stage it has to get past takes a bigger chunk" out of it, Bhattacharya said.

The CDC reversed its mask guidance Tuesday and is now recommending the use of masks indoors in areas of high or substantial transmission, as well as masking for everyone in K-12 schools. "Two things with the delta variant: One is that it's much more infectious than previous variants. And two, vaccinated people can actually spread it to other people," said Shad Marvasti, MD, director of public health and prevention at the College of Medicine – Phoenix.

Banner Health is now requiring all employees to receive the COVID-19 vaccine by Nov. 1, 2021.

Dr. Lorraine Martin-Plank says the pandemic revealed multiple improvements that can be made to help older adults in nursing homes stay engaged and healthy.

With the rise of the über-transmissible delta variant, experts are saying you’re either going to get vaccinated, or going to get the coronavirus. For some people—a decent number of us, actually—it’s going to be both. Coronavirus infections are happening among vaccinated people. To understand the anatomy of a breakthrough case, it’s helpful to think of the human body as a castle. Deepta Bhattacharya, PhD, an immunologist at the College of Medicine – Tucson, compares immunization to reinforcing such a stronghold against assault.