Sunday, July 3, 2022

New Covid-19 model: 750,000 possible NC cases, restrictions might be needed for two months [Free read]

NHRMC staff donning face masks guard the main entrance of the 17th Street hospital in late March, allowing only a limited number of support personnel who are free of symptoms. (Port City Daily photo/Mark Darrough)

NORTH CAROLINA — A team of epidemiologists and data scientists from the state’s top universities and research institutions have released new models forecasting a large spike in Covid-19 cases across the state — and a 50% likelihood that demand for hospital beds will exceed supply — if social distancing restrictions are lifted at the end of April.

The three independent models used composite estimates to indicate roughly 750,000 people across the state may be infected by the novel coronavirus by June 1 “if the social distancing policies are fully lifted at the end of April and are not replaced by other policies with equal assumed effectiveness to reduce transmission,” according to a brief released by the experts.

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“COVID-19-related hospital caseloads are growing but currently manageable. However, considering how COVID-19 has impacted other jurisdictions (for example, Italy, New York, Massachusetts), there are concerns that North Carolina may not have sufficient hospital capacity to meet potential health care needs resulting from the COVID-19 epidemic,” the brief, released Monday, states.

In one scenario, the team predicted a 50% chance that a surge in the number of acute care hospital beds needed for Covid-19 patients throughout the state will exceed supply if those policies are fully lifted and not replaced by equally effective policies to reduce the spread of infection transmission. (The report clarifies that these estimates and forecasts consider the state as a whole and that probabilities will likely vary by region; it also notes that predictions do not forecast an absolute outcome but rather the likelihood that certain outcomes will occur.)

Composite estimates across three independent models show the probability that demand for acute hospital beds will exceed available supply in North Carolina. (Graph courtesy “COVID-19 in North Carolina” report)

Alternatively, if the state maintains social distancing restrictions with similar effectiveness, the experts predict “the peak stress on available acute care capacity will likely occur in mid-to-late May,” but the likelihood of supply exceeding demand would be halved.

“At that time, we estimate a roughly 1-in-4 chance that acute care bed capacity will be insufficient to meet growing COVID–19-related demand,” according to the brief.

Estimates for the availability of ICU beds are similar to those for acute care beds, but with a slightly higher chance that Covid-19-related demand “will outstrip available ICU bed supply in the same time frame (mid-to-late May 2020).”

“These findings suggest that social distancing may ‘flatten the curve’ — thereby spreading COVID-19 incidence over a longer time period, allowing the health care system to better absorb the influx of patients.”

The team estimated that if the state lifts all social distancing guidelines by the end of April, causing an immediate return to the rates of transmission prior to the restrictions, “stress on hospitals to cope with rising demand from Covid-19 patients could begin as soon as Memorial Day.”

The “weather forecasting” modeling was developed by epidemiologists and scientists at University of North Carolina, Duke University, Blue Cross and Blue Shield, NoviSci, and RTI International.

Social distancing measures crucial

“We have life-changing decisions before us and North Carolina is fortunate to have world-class experts who can help our state as we continue battling the coronavirus,” Governor Roy Cooper said in a Monday afternoon release. “Modeling is one tool that helps us prepare for this fight and it shows we will save lives if we stay home and keep our social distance right now.”

The report also noted that social distancing will slow transmission only if communities “adhere to and support them.”

In addition to increasing or maintaining social distancing requirements to minimize the possibility of a hospital bed shortage, the experts recommended the state also increase capacity of the health care system for a possible surge.

By summarizing the group’s preliminary results “of work in progress,” using data as current as April 4, the purpose of releasing the brief is to inform legislators and other policy decision-makers in coming months. The 12 experts collaborating on the project plan to continually add new data to the analyses, according to the report.

Because an insufficient time had passed since the state implemented the stay-at-home order and other social distancing measures, the group assessed potential impacts of those policies by observing jurisdictions where the outbreak has spread sooner than in North Carolina.

The models were compiled with an assumption that hospitals across the state have decreased occupancy by 45%, due to well-documented evidence that hospitals across the state are decreasing elective procedures to reduce occupancy while planning for a surge in needed beds, according to the brief. Using this methodology, the experts estimated there are currently 16,055 hospital beds in the state; 20,843 beds would be needed with a 20% surge and 28,026 beds would be needed with a 50% surge.

“Under current policies, our models suggest that the volume of available acute care beds throughout the state will be sufficient to handle growing COVID-19-related case volume in the next few weeks,” according to the brief.

The data suggests there is now a relatively low probability (10%) that demand for acute care beds will outstrip supply if the policies are maintained, but will likely increase by mid-April.

“In May, the situation likely changes. Our medium-term estimates assume that current policies remain in effect through April 2020. In early May 2020, we see a divergence in estimated probabilities depending on the two social distancing scenarios.”

The experts also predicted that while expanding hospital capacity does lower the probability of a shortage, “the effect is small in relation to the reduced probabilities estimated for social distancing.”

Although expanding bed capacity and adding healthcare workers to staff those beds is crucial, the experts argue that such an expansion alone — without social distancing measures in place — will likely not be a sufficient solution to the estimated demand surge.

The bottom line, according to the brief, is that “[b]oth will need to be addressed: demand for beds (by reducing infectious spread) and supply of beds (by flexing health care capacity and the associated workforce.”

“Put simply, our analysis suggests that in the absence of sufficient social distancing, we cannot ‘surge’ our hospital capacity to the extent we may need.”

Read the full brief below:

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