The Delta Spread: Variant driving new wave of COVID cases in AZ

Gerd Altmann, Pixabay

With more than 2,000 COVID cases reported daily in Arizona in recent weeks, health officials are predicting an outbreak similar to at least the last summer and potentially as serious as the wave of winter 2021.

In his latest weekly COVID-19 forecast released Friday, Aug 6, Dr. Joe Gerald, an epidemiologist with the UA Zuckerman School of Public Health, recapped yet another week of bad news, as Arizona saw a 38% increase in positive COVID-19 cases from last week, with 14,188 Arizonans diagnosed with COVID-19 for the week ending Aug. 1. Further, Arizona is experiencing 50 deaths per week and Gerald predicts deaths will increase in the coming weeks, exceeding 100 per week by the end of August.

Gerald said another wave of cases and hospitalization is certain, due to the prevalence of the Delta variant, which accounts for more than 75% of the cases in Arizona.

As the cases rise, the Tucson Unified School District is requiring all students, teachers, staff and visitors to campuses to wear face coverings in defiance of Gov. Doug Ducey and the Arizona Legislature, which passed a law banning mask mandates in schools and universities.

TUSD is the only school district in Pima County that has decided to outright ignore the state's restrictions on mask mandates, with the TUSD board voting 4-0 to require everyone to wear a mask on TUSD property at an emergency meeting last Wednesday, Aug. 4.

The vote was motivated by the outbreaks seen in the Vail School District and with the growing number of pediatric cases. As of Aug. 5, the Pima County Health Department received reports of 212 positive COVID cases in K-12 schools. In an updated Public Health Advisory, PCHD notes an increase in pediatric admission and ER visits since July 29.

The CDC reports the Delta variant is "more than two times as transmissible as the original strains circulating at the start of the pandemic and is causing large, rapid increases in infections."

Emerging data also suggests lower effectiveness of the vaccine against confirmed infection and symptomatic disease caused by the Delta variant, according to the CDC's brief on vaccinations updated on July 27.

"This outbreak will almost certainly be as big as the one experienced in summer of 2020," said Gerald in his report. "While I am optimistic it will not reach the levels seen in the winter of 2021, the experience of other similar states (e.g., Louisiana, Florida, and Texas) suggests this could be wishful thinking."

Last summer, cases peaked at around 5,500 cases per day of COVID-19, while the winter saw a peak of 12,000 cases per day. Gerald finds the current outbreak is most similar to the winter surge, with both beginning at a rate of 40 cases per 100,000 residents per week. Sixty-five days later, the rates for the winter 2020 and summer 2021 outbreaks were 220 and 195 cases per 100,000 residents per week, respectively.

"While these two curves may diverge, it would be prudent to assume they won't unless we intervene to slow transmission," said Gerald. "Unfortunately, we are squandering the efforts of the vaccinated and ignoring the sacrifices of the previously ill and dead, to party like it was 1999."

Gerald also noted that despite a higher degree of vaccination for those 65 and older the current community transmission is impacting hospitals similarly to how it did last winter.

"Because herd immunity applies to populations not age groups, high vaccination rates among those >65 years doesn't provide any protection to those who interact with unvaccinated adults who have much lower levels of vaccination," said Gerald. "So, we should not hold a false sense of security that this outbreak will necessarily have less impact on our already overburdened hospital system."

At an Aug. 3 press briefing, Banner Health's Chief Clinical Officer Dr. Marjorie Bessel said since July 1, COVID hospitalizations have increased by 95% and ventilator usage has increased by 300%.

According to Gerald, hospitals should be prepared for greater than 15% to 20% COVID-19 occupancy with the high level of transmission.

However, the Arizona Legislature and Gov. Doug Ducey have limited the ability of local jurisdictions and schools to respond to the rise in cases.

Ducey was critical of updated CDC guidance released July 27, recommending individuals mask in public indoor spaces, regardless of vaccination in areas of high or substantial transmission.

"Arizona does not allow mask mandates, vaccine mandates, vaccine passports or discrimination in schools based on who is or isn't vaccinated. We've passed all of this into law, and it will not change," said Ducey in a July 27 press release. "The CDC today is recommending that we wear masks in school and indoors, regardless of our vaccination status. This is just another example of the Biden-Harris administration's inability to effectively confront the COVID-19 pandemic."

But the Arizona Department of Health Services and local health departments updated their guidance alongside the CDC recommendations.

Matching CDC language, Pima County Health Department's updated Public Health Advisory "strongly recommends that all teachers, staff, students, and visitors to K-12 schools wear masks indoors at all times during school regardless of vaccination status."

While children's cases make up about 15% of the cases, an increase from 10% in the winter, Gerald notes that this outbreak, like previous outbreaks, is driven primarily by adolescents and working-age adults.

"Incomplete vaccination among older adults, but particularly among working-age adults, means that hospitals remain at risk of being overwhelmed and a substantial number of deaths can once again accrue," said Gerald.

Despite the dreary forecast, Gerald continues to advocate for vaccinations as the most important public health priority.

In Arizona, 53% of residents have received at least one dose and of those 47% have been fully vaccinated as of this week. In her blog on Friday, Aug. 6, Arizona Department of Health Services Dr. Cara Christ said nearly all cases (89% in July) and almost all hospitalizations and deaths are occurring among adults who haven't been fully vaccinated, or vaccinated at all, in most cases.

"COVID-19 is now a pandemic of the unvaccinated. If you are basing your decision to not be vaccinated on social media claims, I urge you to seek your doctor's advice," pleaded Christ. "I don't want to see more people get seriously ill, go into the hospital or die from COVID-19. In almost every case today, it is preventable with vaccination."

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