August 16, 2021 – What direction are infection rates and deaths headed in the United States? The outlook is cloudy.
This much is certain. Hospitals will admit more Covid patients this week than last. More Covid patients will occupy hospital beds next week than this week. More persons will die with Covid the first week of September than did in any week in August.
Will this Delta wave continue surging? Or will it crest soon?
Experts disagree.
The ensemble forecast, published by the Centers for Disease Control and Prevention (CDC) on August 11, anticipates rising new cases for this and the next three weeks. By early September, new daily infections will be nearly double what they were last week.
The Institute for Health Metrics and Evaluation (IHME) paints a more optimistic outlook. IHME’s latest model (dated August 6) forecasts that new cases peaked as early as yesterday. Even then, IHME model demonstrates the latency between cases, hospitalizations, and deaths. IHME’s expects COVID hospital admissions to peak in ten days, hospital census to peak just before Labor Day, and COVID deaths to peak another week later.
Perhaps the forces underlying the surge (a highly transmissible variant and large numbers of unvaccinated persons) are battling ever-stronger counter forces (a shrinking pool of vulnerable targets for the variant, improved personal behaviors (masking, social distancing), and increasing vaccinations).
We have been tracking the virus every day since March 2020. We maintain a rich trove of daily cases, hospitalizations, testing results, and deaths by the municipality, state, and country. We have tracked each of the infection waves in the United States. By doing so, we have observed a consistent pattern: early in each wave, the rate of change (the algebraic first derivative) turns positive. More telling, the second derivative also turns positive – meaning that the rate of increase begins increasing. This ever-worsening pattern is what we expect from a highly transmissible variant.
We also observed that this exponential growth does not or cannot continue too long. About midway through the wave, both the rate (first derivative) and acceleration (second derivative) of new cases slow then turn negative. Acceleration turns negative first (deceleration), then the rate goes negative. A negative growth rate is the same as declining new cases or a crest in the infection wave.
It is typically weeks between deceleration and the onset of declining cases.
New cases have now been decelerating for two-and-a-half weeks. The rate of case growth has fallen by two-thirds in that time.
A few additional factors point to an impending slowdown. First, testing results have improved in the past week. Since the beginning of the surge, the test-positivity rate had spiked. However, this rate stabilized two weeks ago and began falling last week.
Second, more people are getting vaccinated each day than at the beginning of the surge. Forty percent more people are vaccinated each day now than were in early July. The most significant impact is among 18–49-year-olds. This age group now accounts for 40% of hospitalized COVID patients.
In the past six weeks, the number of fully vaccinated persons in this age group has increased 10%. Nearly 70% of this age group has received at least one dose.
If (and that’s a big if) this pattern continues, the United States could see declining new cases in a week or two.
Relief cannot come soon enough. Hospitals in many parts of the country are straining. Our healthcare providers are exhausted.
Even if new cases start to decline, it will take another week for hospital census to peak and an additional week or two for deaths to recede.
Contributing writer:
Mark A. Van Sumeren, strategic advisor, Medical Devices & Integrated Delivery Networks
Health Industry Advisor LLC, provides a regular report on COVID-19 numbers for the health care industry.
For more information, or to sign up for the report, contact Mark at Mark.VanSumeren@HealthIndustryAdvisor.com; or visit www.HealthIndustryAdvisor.com.