The steep rise in COVID-19 cases that began in July could peak on Labor Day and begin a two-month decline, according to a new state report.

The COVID-19 forecast released Thursday by the Oregon Health & Science University in Portland included an updated “Census Forecast Primary Scenario” of hospitalizations.

“The forecast shows a peak census level of 1,197 on 9/6,” wrote Dr. Peter Graven, the chief COVID-19 analyst at OHSU.

Hospitalizations would make a painful retreat with earlier low levels of COVID-19 hospitalizations unlikely until late October — just before Halloween.

Graven said the toll on the state has been heavy and will continue for weeks ahead with levels of cases remaining high as the virus retreats. Oregon is currently experiencing the highest rate of COVID-19 cases of the 18-month pandemic.

The rapid influx of unvaccinated people arriving with severe infections has pushed the state’s network of medical centers to the breaking point.

“We’re seeing the number of people hospitalized going up at rates we’ve never seen before,” Graven said.

Gov. Kate Brown’s order for mandatory mask-wearing at public gatherings and events inside has not shown to have dented the arc of infections.

“We had hoped to see the new statewide masking mandate make a difference in flattening the rate of infection, but we’re not seeing that yet,” Graven said.

Beginning Friday, Aug. 27, the mandated mask order has been extended to include outside public spaces where people congregate in close proximity. Any impact of that action won’t show up until future forecasts.

While there is now hope that the spike driven by the highly contagious delta variant could be slowing its rocket-like trajectory, there will be a long, costly fall back to levels seen before the spike.

COVID-19 hospitalizations could fall to about 200 patients around Oct. 23. The decline would continue until reaching pre-spike levels around Nov. 6. The forecast shows hospitalizations could continue to near zero by Dec. 25.

The Oregon Health Authority has reported that 95% of hospitalizations and deaths during the last two months have been among unvaccinated people.

Among vaccinated people with “breakthrough cases,” 5.5% have been hospitalized and 0.9% have died. The median age of the vaccinated people who died was 83.

OHA reported 2,057 new COVID-19 cases and nine new deaths Thursday. Oregon has reported 265,210 cases and 3,095 deaths during the pandemic.

Nationwide, over 38.3 million cases have been reported, along with 633,451 deaths, according to the Johns Hopkins Coronavirus Resource Center. Worldwide, 214.5 million cases have been reported and just over 4.47 million killed by the virus.

The latest surge in COVID-19 infections has been driven by the highly contagious delta variant. It was first discovered in India in May and swept across the United States in June and July.

It hit hardest in areas with large populations of people who were unvaccinated since the COVID-19 virus was first reported at the end of December 2019 in Wuhan, China.

Dr. Renee Edwards, OHSU’s chief medical officer, speaking Wednesday during a media briefing prior to the official release of the report, said the current crisis remains dire.

Hospitals reported over 92% of all adult staffed beds were occupied. Intensive care unit beds often had even fewer openings. Reports of patients backing up into emergency rooms and ambulances unable to bring in new patients came from around the state.

The death of a patient in Douglas County waiting in an emergency room because of not enough intensive care unit beds being available made international news.

Edwards said a graphic of the spike showed a roughly symmetrical rise and fall, with the increase from early July mirroring the projected drop over a similar period.

”The downward angle looks kind of exactly like the upward angle, that the path back down would look just as steep and long as the path up,” Edwards said.

OHSU scientists underlined that the forecast peak was not the end, but the middle of the current crisis. An equal number of unvaccinated people are expected to get sick during the next two months.

The 218 deaths in August so far are the fourth highest monthly total of the 18 months recorded by OHA, with the final total for the month unknown until midnight Tuesday.

Progress toward improvement could stall if residents get “COVID fatigue” and become complacent about masking, getting vaccinated and other safeguards. The delta variant has increased cases 12-fold since early July.

Unvaccinated people are also a potential breeding ground for new variants, which could be even more contagious and virulent than the delta variant.

OHSU reported Thursday that just over 63% of all Oregon residents are vaccinated. That includes children under 12, for whom there is currently no federally approved vaccine. Oregon ranks 19th in the nation for overall vaccination rate.

Edwards said that until most of the world is immune, variants could come from the next city or from around the world.

”That’s what viruses do,” Edwards said. “Viruses are constantly changing and mutating and looking for their best opportunity to spread.”

Oregon could approach herd immunity — in which the total number of people who are either vaccinated or been exposed to the COVID-19 through transmission slows or stalls the ability of the virus to spread.

Edwards said Wednesday that Graven’s forecasts have shown reaching herd immunity is possible — but at a much greater human cost than through vaccination.

”Dr. Graven said we are getting to herd immunity, but through mass infection, which is not the way to get there because too many people get sick, too many people die and it overwhelms our health care system,” she said.

The OHSU forecast is an estimate. The Aug. 18 report forecast hospitalizations peaking at 1,075 on Sept. 3. However, hospitalizations hit 1,080 on Aug. 25.

The World Health Organization said Wednesday that the worldwide spike caused by the delta variant had appeared to be peaking, with the United States timeline lagging due to a later onset, vaccination level and infection transmission patterns.

The current spike was dubbed the “Fifth Wave” as cases climbed for a fifth time in the state since the first infection was reported in late February 2020. Lulls in cases have come during periods of business and event restrictions, high mask requirements and beginning late last December, the arrival of vaccines.

COVID-19 cases have risen for eight weeks, shortly after Brown lifted most pandemic restrictions on June 30. The move came as the Centers for Disease Control said that vaccination efforts across the country had made it possible to lift most limits on social interaction.

But the delta variant soon changed that narrative as it tore across the country.

On July 18, OHA reported 120 COVID-19 cases. The daily case count hit 1,025 on July 26. It was 1,560 on Aug. 2, then 2,302 on Aug. 9. The record 2,957 cases were reported on Aug. 19. The less volatile 7-day average crossed an average of 500 daily cases on July 26 to over 1,000 cases on Aug. 4 to 2,000 cases on Aug. 18. Thursday it hit 2,194.

Brown has sent 1,500 Oregon National Guard troops to hospitals around the state, primarily for non-medical support of civilian staff.

Brown on Wednesday said she had approved contracts worth up of up to $120 million with companies in California and Colorado to send about 560 out of state nurses and other medical personnel to hospitals operating at or near crisis proportions.

The temporary staffing will fan out to key medical centers, including the St. Charles Medical System hospitals in Bend and Redmond, as well as hospitals in Roseburg and other areas with high case loads of severe COVID-19 patients.

OHSU had forecast early in August that the state could be especially hard hit by the delta variant because of a unique combination of conditions in Oregon.

Under and “Immunity Index” developed at OHSU, Oregon ranked in the top 10% of states in vulnerability to a surge in cases this summer.

One one hand, Oregon had acted swiftly after the first COVID-19 case in the United States was reported at the end of January in adjacent Washington State.

Brown moved to swiftly put restrictions in place that kept infection levels low as the virus hit the state at the end of February.

Differing levels of COVID-19 infections and deaths were reported as states took differing approaches to the virus — some shuttering while others made decisions to keep businesses open and limit restrictions such as mandatory masking. The states with fewer restrictions overall saw higher levels of illness and fatalities in the first wave of infections.

But the exposure also increased the percentage of people who developed an uncertain level of natural immunity to the original virus.

When vaccines arrived at the end of the year, Oregon was among the five states with the lowest levels of cases during the pandemic and ranked low on total deaths.

Brown had hoped the situation would be maintained by a rapid rollout of vaccinations that would keep infection levels low and give Oregon one of the top overall outcomes when the pandemic subsided.

At first, the plan seemed to work. By April, up to 50,000 people a day were getting shots — mostly the two dose Moderna and Pfizer vaccines that gave strong immunity after about six weeks from the first shot.

But vaccinations in Oregon went from overwhelming demand in March to overstocked by May as the number of people eager for shots gave way to a large pool of residents who were either vaccine hesitant or, in some cases, “vaccine belligerent,” as OHA Director Pat Allen told the legislature during a spring hearing.

Vaccination rates for eligible adults were uneven across Oregon’s 36 counties, ranging from 70% in the Portland area to 40% and below in some vaccine resistant strongholds in eastern and southwestern Oregon.

The highly contagious delta variant of COVID-19 had been discovered in India in May, and was spreading through the United States in June. When it hit Oregon, it ravaged unvaccinated communities with record infections and hospitalizations.