As you know if you’ve been following this blog throughput the pandemic, Joe Gerald, MD, PhD had been publishing weekly epidemiology and hospital capacity reports to help inform public health policy. He suspended those updates a couple of months ago- but wrote a supplemental report today owing to the impact that the Delta Variant is having in Arizona given our relatively anemic vaccination rates. From Dr. Gerald:

Given increasing COVID-19 rates and greater prevalence of the more transmissible Delta variant, I thought it appropriate to provide another update. Like my May update, Arizona continues to chug along with COVID-19 case rates of about 50 cases per 100,000 residents per week after making some progress. The major difference being that Mohave County, not Maricopa County, is behaving badly this month.

My best guess is that much of the recent increase in cases and hospitalizations is attributable to the July 4th holiday (short-term) overlaid on greater transmission pressure due to the Delta variant, waning individual precautions, and continued absence of any effective state mitigation efforts (long-term).

Nevertheless, reasonable levels of vaccination supplemented by a relatively large number previously infected but recovered individuals is providing sufficient population immunity to prevent a substantial resurgence like last summer. Basically, keeping a lid on things. I don’t think the pool of remaining susceptibles is large enough to facilitate sustained, large increases. Instead, transmission is more likely to hover 50 cases per 100K residents per week for the next month or so.

Our priority must be continued vaccination of adolescents/working-age adults to slow transmission and vaccination of older adults to prevent hospitalizations/deaths even though this latter group has already achieved 75%+ vaccination levels. While it ain’t going to happen, imposing mask mandates would drive transmission rates to even lower levels prior to school re-openings this fall.

As I mention in my update, the CDC erred when it tied mask recommendation to individual risk rather than population risk. That mistake has allowed COVID-19 to hang around at higher levels than it should have.

My ASU, NAU, and UA colleagues and I continue to monitor the outbreak and will alert you if conditions meaningfully worsen. We have experienced a tremendous collective trauma these past 18 months, and it is only natural to fear the other shoe is going to drop any minute. However, I convinced both shoes have already fallen with one grinding our face in the dirt this past January. In that spirit, I’m trying to tamp down my hyper-vigilance and heightened anxiety to new COVID-19 stimuli.


Except for small oscillations around 50 cases per 100K residents per week, viral transmission has not changed much since April of this year. Moderate levels of transmission are expected through the summer. Continued normalization of behaviors along with more transmissible variants (e.g., delta) will be mostly balanced by immunity from vaccination and recovery from past infection.

As of July 7th, new cases were being diagnosed at a rate of 56 cases per 100,000 residents per week. Over the next several weeks, rates can be expected to change relatively slowly, +/- 5 – 10 cases per 100,000 residents per week, as we continue to hover around Rt values of 1.

The emergence of another large wave of cases and hospitalizations seems unlikely despite the increasing prevalence of the Delta variant. While Arizona has not achieved herd immunity, total immunity is high enough to prevent a repeat of the past two outbreaks. However, unvaccinated, partially vaccinated, and immunocompromised individuals will remain at risk of severe infection as community transmission is expected to persist at moderate levels. o Vaccination remains the most important public health priority to reduce viral transmission among everyone and severe illness among those at greatest risk.

While not expected, mask mandates would lead to faster disease reduction by decreasing transmission in public settings. In retrospect, mask mandates should have been tied to population case rates (e.g., <10 cases per 100K residents per week) or some population vaccination goal (e.g., 80% fully vaccinated) instead of being lifted based on risk of infection to the individual. This was, and continues to be, a significant policy failure/error at the state and federal level.

With inadequate vaccination uptake, eliminating COVID-19 is no longer a plausible public health policy goal. COVID-19 is almost certain to become an endemic disease with varying temporal and geographic implications. Fortunately, vaccination will remain a viable disease control strategy offering a high degree of protection to those willing to accept them.

• Hospital COVID-19 occupancy is holding steady in the ward and ICU at 5 – 10% of occupancy. Access to care remains somewhat restricted as overall occupancy remains unseasonably high at 85%.

• Arizona Covid-19 fatality counts are now <50 deaths per week should remain below that level unless case rates meaningfully increase.

• According to the CDC, 54% of Arizona adults have received at least 2-doses of vaccine while another 8% have received 1-dose. Arizona passed peak vaccination rates in early April and these rates continue to erode. We are unlikely to achieve 70+% vaccination of our eligible population and should be prepared to adjust to COVID-19 as persistent risk. o Despite evidence of limited immune escape to the Delta variant, especially before completion of the full vaccination sequence, vaccination continues to provide extraordinarily high levels of protection from infection and severe illness.