A mural honors health workers at the Mission Hospital in Pasig. The daily average of new cases has gone down significantly this week. Photo by Jonathan Cellona, ABS-CBN News
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Our daily average of COVID cases says we are bending the curve—but when will we flatten it?

Based on data recorded, this week has confirmed that we are bending the curve. Our resident expert now explains how to tell if we’re finally flattening it. BY BENJAMIN CO MD
ANCX | May 23 2020

Infectious diseases and clinical pharmacology expert Dr. Benjamin Co has been thankfully breaking down coronavirus numbers in his personal blog since the outbreak started. The perspective he provides is informative, and comforting in those who are craving for a clear picture of how we are faring against the virus. Dr. Co will share daily updates and analysis of the Department of Health reported numbers with ANCX. 


There are two terms that are used complementary to one another to determine if a country has the pandemic under control. 

“Bending the curve” refers to the graphical representation that the number of daily cases is plateauing and later on sees a continuous decline in the trajectory of the curve.

Figure 1. Are we bending the curve? 

Figure 1 above illustrates the current condition of various countries based on days since the first cases reached 30/day (X axis) and the number of cases (in logarithmic scale, Y-axis). One can see that there are countries that are still on an upward trajectory while others have begun to bend their curves, whether slightly, or significantly.


Has the Philippines bent its curve?

Figure 2. Daily confirmed deaths due to COVID-19 (United States, Italy, Indonesia, the Philippines, South Korea, and Brazil)

Figure 3. Daily vs total confirmed deaths due to COVID-19 (in red is the United States). Other countries illustrated include Brazil, Italy, South Korea, Indonesia, and the Philippines. 

Figures 2 and 3 above show how we are faring. While the United States may have the most cases in the world, they have also begun to bend the death curve with less daily deaths vs total confirmed cases as well. Brazil on the other hand is the new epicenter in the world to watch out for as its death rates begin to climb staggeringly. Indonesia still has an upward trajectory for deaths (in proportion to their upward trajectory in cases, see Figure 6 below).

The other term used by epidemiologists is more commonly known as “flattening the curve.” Let me delve on this a bit as this has caused some confusion among the public.

Figure 4. Illustration of the concept of flattening the curve

Flattening a curve does not imply that it should flatten to zero. It is a misconception that a curve, in order to be called “flattened,” is pressed to the ground.

In a pandemic, the curve varies in shapes from country to country, with some countries taking a steeper climb than others. As a general rule, when a country has a steeper rise in cases (more people get infected), it will also have a steep fall (the patients either get better or die because the virus has infected a large segment of the population already). 

A steep rise in cases carries a large burden on the health system. Too many sick people overwhelm the healthcare system, and overloading beyond the capacity to treat people results in greater death rates. More people die not only because there are no more hospital beds, but the overall health system—from healthcare workers to basic supplies—are exhausted rapidly. 

The ECQ, social distancing, hygiene, wearing masks and other ways at minimizing the transmissibility of an infection from one person to another (i.e. school closure, limiting travel and work, closing borders and minimizing movements) are ways to flatten the curve. A flatter curve does not mean that we pummel the curve to the ground. (Although, wouldn’t that be great?) When we flatten the curve, we slow down the infection rate. It assumes that the same number of people eventually get infected, but over a longer period of time. Slowing down the infection de-stresses the health care system.

That’s the story of the COVID-19. 

There is currently no vaccine or drug to treat this disease and we’re all scrambling at the availability (or unavailability) of testing. The collective action of everyone in the community is needed in order to address the challenge of seeing a decline in the COVID19 cases.


Have we flattened our curve?

Figure 4 above illustrates the healthcare capacity of a country in the broken lines. Without precautions during a pandemic, the number of people infected would be disproportional to the healthcare capacity resulting in a direct collapse of the latter, indirectly leading to more deaths. The “flatter curve” (in orange) has the same area under the curve (number of patients) but spread out over a longer period of time when compared to the steeper curve (in dark pink when no precautions are observed).

Figure 5. Image from the CDC and criteria for claiming the “flattening of the curve.”

There are two major criteria (shown in figure 5) to say that the curve has flattened. One, a slow acceleration of number of cases, and two, reduction in the peak number of cases and related demands on hospitals and infrastructure. I would boldly venture on saying that the overall reduction in death rate is an ideal parameter to indicate that we’ve reduced the demand on hospitals and infrastructure.

As of May 20, 2020, the DoH reports that facility capacity of various hospitals in the Philippines is not overwhelmed. Only 34.5 percent of total ICU beds and 17.8 percent of mechanical ventilators are being used. 

The death rates have also dramatically dropped weekly. From April 26 to May 2, the average deaths was 16/day. May 3 to May 9 showed an average of 15/day. May 10 to May 16, an average of 16/day. May 17 to May 23 show a dramatic drop to six/day.

Number of new confirmed cases are also on the decline. The last four weeks (since April 26) saw a seven-day average of 240 cases/day. To say that we’re slowing the acceleration of cases is to see a conservative decline by at least 10 percent from the average of the previous week. We ended last week with an average of 242 cases/day. I wanted to test the threshold of 225 cases/day for the week. The seven-day average for the week of May 17 to 23 is 210!

With this new seven-day average for last week, we now test the threshold of 190 cases/day for the coming week. If this is sustained in spite of latent data, then we can confidently say that we have not only begun to, but we have flattened the curve. (This has to be something consistently seen over a 4 week period.)

Figure 6. Daily vs Total confirmed COVID-19 cases (US, Italy, Philippines, Indonesia, South Korea, and Brazil)

Figure 6 above shows the Philippines and the United States plateauing on cases, with Brazil now in an upward trajectory. A plateauing of cases means a slowing down in the trajectory (shifting the curve to the right). If we sustain the 10 percent decline of the weekly threshold, we will have similar bending curves as South Korea and Italy. While Indonesia may have lower death rates compared to the Philippines, its cases remain on an upward trajectory and have not plateaued yet. 


Statistics for the day

The world is now at 5,328,548 confirmed cases with 340,425 deaths (6.39 percent case fatality rate) and 2,175,290 recoveries (40.8 percent case recovery rates). The ratio of recoveries to deaths is higher at 6.4:1.

Back home in the Philippines, the Department of Health has publicly announced 180 new cases, 85 new recoveries, and 6 new deaths.

Our case fatality rate has improved and is now down to 6.26 percent with recovery rates up at 23.06 percent. Globally, we rank now lower in recovery rates at 140 (out of 165 countries), and are doing much better at number 30 (from number 29) in death rates. 

The Department of Health website has not updated the Data Drop files as of this writing but reported that of the 180 new cases today, 114 (63 percent) are from the NCR while the remaining 66 (36 percent) are from others. The NCR remains to be a hotspot contributing to more than 60 percent of the daily cases reported in the Philippines. 


Testing Capacity

As of May 22, 2020, a total of 287,294 tests have been done among 265,061 individuals with 20,264 testing positive (7.6 percent positivity rate). There were a total of 9,504 tests done yesterday alone (6 percent of who were positive). As of yesterday, there are 7,128 samples in the backlog. 

Disclaimer: All information provided in the daily reports and updates are based on the Data Drop of the Department of Health website. The accuracy of information is dependent on the information released from the DoH. All other graphs, citations and projections are referenced appropriately. Any change in future data particularly on latency reporting may affect the overall trend cited in this post.