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Delta variant fueling increased Covid-19 infections

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TUCSON (KVOA) - Last week the Centers for Disease Control announced new mask guidance, recommending vaccinated people mask up inside. This comes as the Delta variant, which first emerged last year in India, becomes the dominant strain of Covid-19 in Arizona and the United States.

The Delta variant is definitely a game changer for the vaccinated and the unvaccinated.

"Infections overall have been increasing, And we know that breakthrough infections are bound to occur even with highly effective vaccines out there. so we are seeing and hearing of more examples of breakthrough infections," said epidemiologist Dr. Kate Ellingson, an assistant professor with the University of Arizona's College of Public Health.

For many vaccinated Americans, the pandemic was over. Most mask restrictions had been lifted and people were returning to pre-pandemic life. But the Delta strain is causing a pandemic whiplash. "Delta is so much easier to catch because it the virus just spreads out in the air so easily and the virus latches onto your cells inside your body more quickly which makes it more likely a person can become infected," said Will Humble, Executive Director of the Arizona Public Health Association.

Many studies are looking at just how much Delta is turning the pandemic on its head. The viral load is 1000 times higher in people infected with Delta than previous strains, according to one Chinese study.

Researchers say the incubation period is also shorter, four days in Delta compared to six in the original strain. And another study found mutations in the spike protein which could help it dodge the immune response. Ellingson said this highly transmissible Delta variant, coupled with a society that is returning to normal but not yet fully vaccinated is behind the increase we are now seeing in covid cases.

Infections have increased in Arizona over the past six weeks. The Pima County Health Department said 522 breakthrough infections have been reported since July 19. There were 17 hospitalizations and two deaths. This is out of 544,962 fully vaccinated people.

Researchers are trying to determine who is at a greater risk for breakthrough infections. "We don't know entirely why some people have break through infections and some don't," said Dr. Jeff Burgess, Professor and Associate Dean for Research at the Mel and Enid Zuckerman College for Public Health at the U of A. "But we're seeing breakthrough infections in other individuals that don't clearly have immune suppression," he said.

Burgess is also leading studies with AZ Heroes. It's a two-year research project funded by the Centers for Disease Control and Prevention. Researchers are now enrolling kids, ages four months to 17 years in the AZ Heroes Kids Study.  Researchers will look at SARS-CoV-2 infection in children and teenagers and how well the COVID-19 vaccine protects from infection.

While this new wave comes as Arizona had thought it was leaving the pandemic behind, health experts say vaccines still offer a high level of protection against severe illness and death, even with the Delta variant. "If you are fully vaccinated and you get the illness you are 700% less likely to need to be hospitalized, 2000% less likely to die," Humble said.

Shelle Jackson

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