An analytical look at the COVID-19 statistics for North Carolina

by Steve Murphy

North Carolina – Over the past week, a lot has changed. For example, North Carolina has started to release death statistics and cases broken down by Congregate (nursing home, residential facility, prison) and Non-Congregate (general population). Also, we have seen significant outbreaks in the Congregate facilities that has increased the percentage of people over the age of 65 dying.

I have attached several graphs that show what is happening over time (I have maintained time-series data every day) and many of these now include a 7-day moving average trend line. I chose seven days, due to the unevenness in the release of data by the NCDHHS and apparent lags after each weekend. Some good news. North Carolina has not seen a spike or severe rise in cases and deaths. North Carolina is likely to see more of a sustained leveling than a spike like other states have seen.

IHME Model Tracking:

I have been tracking every version of the IHME model (Washington model used by the Federal task force and many states) and comparing its projections for mean daily deaths against the actual daily deaths. As you can see from the attached graph, the actual deaths are tracking close to the 4/21 version and this has been the most accurate version (closest to actuals) that IHME has produced. As I pointed out in my last post, based on the projections, North Carolina has never been close to the healthcare capacities for hospital beds, ICU beds, and ventilators. Also, I should point out that all of these models assumed social distancing, so this was not the cause of the difference. It was based fundamentally on a lack of good data early on to produce accurate forecasts. As the data has improved and we have learned more about how the virus progresses, the models have improved.

Cases:

The next graph I have included is a plot of daily new cases. I do maintain a cumulative cases graph, but it is not something you should really focus on. Several news channels still like to report cumulative cases, but it is not worth looking at. We will continue to see increasing cases for at least a year and a half and likely longer (will provide more info on this later). You will notice in the plots that the last eight days includes a split of Congregate and Non-Congregate daily new cases. This helps you see the effect of the rise in nursing home cases on North Carolina’s overall case rates. When I last posted, I noted that case rates were starting to flatten, but right after this post, we saw large numbers of outbreaks in congregate facilities throughout North Carolina. This is actually a horrible event which I will discuss below. For the past seven days, we have averaged 370 new cases a day.

One of the causes for a rise in Congregate care facilities as it relates to prisons appears to be related the policy NC has that has allowed prisoners on work-release to continue to leave the prison for jobs. They have been leaving to work at fast-good restaurants and other businesses, becoming infected, and then returning to the prison, only to infect other prisoners. Quite frankly, this is the wrong policy. All Congregate facilities need to be locked down.

Deaths:

For this update, I am providing the death statistics by age in a different way – by showing the percentage of people that survive having the virus (based on NCDHHS updates):

1-17 years old = 100%
18-24 years old = 100%
25-49 years old = 99.7%
50-64 years old = 98.8%
65+ years old = 88%

These percentages are based on the number of lab-verified cases and lab-verified deaths. One thing that has changed from my last update is that the 86% of the deaths are now people 65 and older. At the time of my last update, it was 80%. This is definitely being driven up by the increase in the deaths coming from nursing homes.

I have included two graphs showing the trends on deaths. The first graph shows all deaths and shows the Congregate and Non-Congregate deaths as stacked bars. There is another graph that shows only Non-Congregate deaths (general population) and has you can see from this graph, deaths for the general population have declined sharply. The average deaths per day for the past eight days breaks down as follows:

Congregate Deaths = 12 deaths/day
Non-Congregate Deaths = 5 deaths/day

One piece of news out of Mecklinburg County today is that of their 43 deaths, 40 of these deaths had other pre-existing health conditions that contributed to their death.

Fatality Rates (CFR):

There are still questions about the true CFA (Case Fatality Rate) for the virus and this estimation is complicated by the fact that many people have had the virus, but their cases have not been counted in the official count. Based on some recent anti-body studies out of NY and Miami, it appears as many as 6% (Miami) to 14% (NY, not NYC) of the population may have been infected. If you make an assumption that cases are double the official count (18,000 cases) for NC, you would get the following CFR’s:

1-17 years old = 0%
18-24 years old = 0%
25-49 years old = 0.17% <== Flu is 0.14% (2017-2018)
50-64 years old = 0.62%
65+ years old = 6.00%

Double the number of cases is not out of the question, considering many people were told to not bother being tested due to mild symptoms or they were asymptomatic the whole time.

Hospitalizations:

The number of people in the hospital is trending up slightly, but the average over the past week is 458 people. The rate of change had flattened out until the increase in cases in the Congregate facilities. Since this time, hospitalizations has bumped up. If the Congregate facility cases stabilize, I expect hospitalizations will begin to decline.

Lock-down Effectiveness:

I am certain lock-downs and their effectiveness will be discussed for years. We all know that the lock-down has been devastating to the state’s and nation’s economy and it will take months, if not years to recover. We know some countries like Sweden chose to keep their economy open and only try to protect those people most at risk – people with pre-existing conditions and the elderly. I have seen mixed reports on the effectiveness and it may be some time before we know if this was a better alternative. As of today, Sweden’s mortality rate is similar to the mortality rate seen in the US, but it will be a few more months before we know if this stays the same. If it does, it may provide a roadmap for how we proceed in the future.

photo by Sandie Clarke

Since I have been maintaining time-series data, I can look at the cases and deaths that came before and after the lock-down in NC. Based on information indicating that symptoms show up 5-10 days after exposure, I estimate 5,400 people have been infected AFTER the stay-at-home orders were issued for NC. If you assume someone is sick for 20-25 days (used 25 days), it means the deaths occurring now were all people who were infected after the stay-at-home orders were put in place.

photo by Fernando Zhiminaicela

Testing:

According to the Federal task force in an update a couple of weeks ago, North Carolina has enough physical capacity to test 500,000 to 999,000 people per month. As of yesterday, they indicated they will be able to supply enough testing supplies to test two percent (2%) of the population. Testing does not need to test everyone. It only needs to test enough people to provide for surveillance of the population. A couple of weeks ago, the state’s health director indicated they need to be able to double daily testing, so this would be approximately 7,000 tests per day. The key to test are:

  • 1. Workers and residents of Congregate facilities with at-risk populations.
  • 2. Workers in hospitals
  • 3. Workers in the food chain supply (NC is finally doing more of this)
  • 4. People presenting with symptoms

Additionally, we need anti-body testing to determine the spread. There is currently no approved anti-body test, but there are trials underway, so we should have this testing soon. According to Dr. Birx, it would also help if we had an antigen test, but these are very hard to develop and it will take a breakthrough. These types of tests are not quite as accurate as an RNA test (testing we are doing now), but it would be faster and accurate enough for daily screening.

Also, need contact tracing capabilities and this is coming. The state health director indicated today that NC will immediately begin hiring 500 people across the state to do this function.

Summary:

As I mentioned in my last post, it is important to remember the stay-at-home orders were put in place to flatten the curve and to limit the demand on our healthcare capacity. Based on the results so far (and the latest IHME model), North Carolina has accomplished this goal. The stay-at-home orders were not put in place to eliminate the virus or to insure there would be no future cases and deaths. As such, I strongly believe North Carolina can begin to open up in a couple of weeks, at the latest.

photo by Edwin Hopper

Of course, we know we will need a vaccine and everyone is hopeful we will have one in a year. I would caution everyone to hope for this, but to expect it to take longer. Typically, it takes five to ten years to develop a virus and in some cases, there are virus we still have no vaccines (TB is an example). Additionally, manufacturing vaccines in large quantities is problematic and it may take a couple of years (estimates say 2-3 years) after we have a vaccine to manufacture enough for everyone in just the US.

One thing that is not evident from these graphs is how much cases and deaths differ across North Carolina. There are some counties and even regions of the state that have seen limited (less than 10 deaths, less than 50 cases) impact from the virus. Other areas, such as Charlotte and the surrounding counties have seen significant numbers of cases and deaths. As such, there may be areas of the state that can begin to open up more quickly than other areas of the state.

I hope you find this information helpful. All of the charts and death data come from the NCDHHS website.

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