Daily COVID-19 Briefing: 4/22/20

Top news, reports and insights for today:

  1. U.S. deaths spike, set new daily high. Weekend reporting lags skew the picture
    On Tuesday, a record high 2,627 Americans died of lab-confirmed COVID-19, a rise of 7%, calling into question the trend toward declining deaths. Seventeen states matched or exceeded their previous high daily death count: Arizona (21), Colorado (37), Hawaii (2), Wyoming (4), Indiana (61), Michigan (232), Minnesota (17), Nebraska (5), Oklahoma (21), Alabama (31), Kentucky (17), Mississippi (14), North Carolina (34), Delaware (10), Maryland (68), New Jersey (376), and Pennsylvania (360). Making sense of the up-and-down of deaths continues to be especially difficult. I am now convinced that we are seeing a pattern in our reporting over the past few weeks that contributes to the confusion. I believe we are seeing a consistent lag in the reporting of deaths over weekends. Below I show you my daily death counts, but there is something new. I darkened the color of Sunday and Monday reports (darker pink). The pattern is striking. The ping-ponging in deaths may be a function of a lower ascertainment rate over the weekend. It’s not apparent on Saturday because those are deaths occurring Thursday and Fridays. Over the last month, reports issued on Sunday and Monday are dramatically lower than the rest of the week. Tuesday reports have been correspondingly spiking as administrative paper work catches up to the weekend lag. To be sure, some of the inconsistency results from states injecting new deaths as big batches of test results coming in, or reporting procedures change. If I am right about this pattern, we keep getting seduced by an apparent drop in new deaths on Sunday-Monday, only to be disappointed by a mid-week resumption of increasing deaths.
    What does it mean? It is challenging to put this unwelcome news into context. As I have said recently in this space, it is important to look not just at daily numbers but at larger trends. Let’s see if the longer term trend is flat growth in deaths or continued rise. In the meantime, we need to pay attention to those states now with elevated epidemic intensity (see lower graph). Pennsylvania, for example, has seen 87% growth in deaths over 3 days.
  1. Good news: with all this uncertainty, there is something really important that we do know
    In what I consider a deeply unfortunate and ill-timed opinion in the Los Angeles Times today, Mariel Garza opines that “everything you know about the coronavirus is wrong”. Well, she is wrong. It is true that every day, we are confronted with things we don’t know. Can I get reinfected? What’s the real case fatality rate? If I have antibodies, am I immune? When is this going to be over? Lots of uncertainty to be sure.
    The good news is that we do know something really important. I have hesitated to bring this up, because it requires some math, but I think it’s time to explain something very powerful that we do know. The topic is this: when and how will we know when we have hit peak in the US? The term peak is thrown around all the time, but what does it mean? Before I get there, consider this: we do know what the epidemic curve for this outbreak looks like. First, let me show you what that curve does not look like. Below are 3 bone-head-simple graphs of what the epi-curve could look like in theory. Figure A shows cumulative growth in new cases for the linear model. In this graph, cases grow along a straight line until there is nobody left to infect and the epidemic stops. Unless you have been under a rock, you already know that this is not the reality we are living in. Every country hit with the epidemic has seen non-linear growth of cases. It’s actually been exponential in every country at least for a time. Figure B shows what the epi-curve would look like under an exponential model of cumulative case growth. When we look at countries that were first to be impacted, like China and now Italy, we know that this isn’t our reality either. Epidemiology 101 tells us that at some point, there are not enough susceptible people left to fuel the outbreak and the rise of new cases slows and eventually stops. In nature, exponential growth of anything can’t continue indefinitely. Based on the way epidemics behave everywhere, we know that the COVID-19 outbreak is following a logistic model (Figure C). That implies three distinct phases: initial exponential growth, followed by linear growth, and then a final phase of declining growth. We have the math to describe this curve pretty accurately. The problem is that the data we have at any one point is not good at telling us where on the curve we actually are. Due to something called the “base-rate” problem, predictions based on this curve are very dangerous very early in the epidemic when the prevalence is low because the disease is still rare. That’s one reason models are so wildly variable. We know that the key thing we should be looking for is the inflection point (see Figure C) in the middle of the logistic curve where exponential growth transitions to linear growth. If we can identify that point, we know that something really important has changed. We know that we are about half way to peak in cumulative cases. We know the rate of change in new cases has peaked and the outbreak is slowing. Back to the key question: what is peak and when do we know we are there? First, peak is not the top of the cumulative case curves. That won’t happen until the epidemic is “over” (which is not likely for another 6-18 months). The peak that matters, and that we know will come, is the point at which growth in new cases shifts from exponential to linear, at which point, new cases will shift from increasing to decreasing, and the rate at which people are recovering will exceed the rate of new infections.
    So what should we look for? In order to see the inflection point, we have to look at growth-rate in cases in the logarithmic scale to see where new case change flattens. Not new cases, but new case growth. More precisely, the best thing to look at is a graph that shows log of new cases over a week plotted, against all previous cases, both expressed on the log scale. This log-log plot doesn’t use time on the X-axis for complicated reasons. The inflection point shows up very clearly as a sharp drop in the growth trajectory. The bottom graph comes from a terrific website created by Aatish Bhatia that computes this exact graph for many nations. The green line (my annotations) shows just how similar all nations are during the period of exponential growth. The green circles show the tell-tale sign of the inflection point, clearly visible in Hong Kong, China, South Korea, Australia and Taiwan.
    The bottom line: We know something very powerful about this epidemic; we know what the epidemic curve’s shape will be, because we know what “model” is underlying the epidemic. We need to look at the data the right way to know when the inflection point has happened. Peak growth in new cases means the rate of new infections has shifted. Reopening the country before this is clear will lead to an unnecessary re-ignition of infections. The figure shows the US is now wavering. The period of exponential growth is slowing and possibly nearing an end. However, it suggests peak in rate of growth in new cases has not yet occurred; there is no clear drop. The US has not yet peaked. We do, however, know what to look for moving forward.
Screen grab taken on April 21 of an interactive graph created by Aatish Bhatia in collaboration with Henry Reich at https://aatishb.com/covidtrends/. Figure based on data from Johns Hopkins CSSE and the New York Times. Green stuff are my annotations of this slide.
  1. What a difference a month makes, the pandemic moves east
    Every once in a while, I like to wind the clock back and see where we were a month ago. Yesterday I glanced back at March 21. The two figures below show just how ‘long ago’ that was. The pie graph on the left shows deaths by region yesterday. The Northeast region has been the clear epicenter of the outbreak last month with 64% of all US deaths. One month ago, the US had recorded less than 300 total deaths! Yesterday, we saw nearly 3,000 deaths in 24 hours. A month ago, the largest fraction of deaths was in Western states (43%). I doubt anyone would have predicted on March 21 that the epidemic would shift so dramatically toward the northeast. Not many believed then that we would lose 40,000 Americans in just 1 month. But, that is what happened. That itself doesn’t tell us where we will be on May 21, but it does remind us that tomorrow’s hot spot may not be the place we are focused on today.


Daily COVID-19 Briefing: 4/3/20

Top news, reports and insights for today:

  1. A tale of 5 Thursdays: what non-linear change looks like
    There were almost 29,000 new cases added yesterday. Quick, try to remember how many there were last week. One theme of my blog has been learning to think in terms of exponential change. It’s something we aren’t used to and it takes practice. It’s also vital for understanding epidemics. The figure below shows the epidemic curve for U.S. cases since March 1. This is the same figure I show every day or two. The difference here is that I have highlighted one week changes over the past 5 Thursdays. How many cases last Thursday? Answer: just over half as many (17K). Two weeks ago? Four thousand. The week before that? Four hundred. The week before that? 64. Since March 5, less than a month ago, we went from 64 new cases to 29,000, a 450-fold increase. Since that Thursday, new cases increased 6-fold, then 10-fold, then 4.3-fold, 1.8-fold.
    What does it mean? It is tempting to think that the rate of growth in new cases is slowing, that social distancing may be flattening the curve. That may partly be true. However, as I have said before, it’s also possible that we are seeing a flattening in testing capacity. Where will we be four Thursdays from now?
  1. U.S. adds record-breaking 1,075 deaths, passing 6,000
    Thursday saw a 23% rise in deaths continuing a pace of doubling every three days. Just two weeks ago, just 55 deaths were reported. States with noteworthy rises include Nevada (+45%), Florida (+42%), North Carolina (57%), Connecticut (+32%), and New Jersey, where numbers doubled in one day with 182 new deaths. New York continues to lead the nation with 2,373 deaths. The Wall Street Journal reports that the City’s crematory operators are handling triple the number of bodies as rules are suspended allowing them to operate around-the-clock. However, the fraction of all U.S. deaths in New York continues to fall slowly (now at 41%) as the pace of outbreaks accelerate in states like New Jersey, Connecticut, Massachussetts, Michigan and North Carolina. The U.S. now ranks third behind Italy (>13,000) and Spain (>10,000) with a combined total of over 6,000 COVID-19 fatalities.
  1. Concerns rise about possible airborne transmission, wider use of masks now under consideration
    Elizabeth Cohen of CNN reports yesterday that a prestigious panel of scientific experts told the White House that transmission of the virus that causes COVID-19 might be occurring through airborne routes. It had been believed that the main route of transmission was through respiratory droplets from coughs and sneezes that land of surfaces and are picked up through touch. That still may be the main way the virus spreads. However, the expert panel said that new findings “are consistent with aerosolization of virus from normal breathing“.
    What does this mean? While this question remains hotly debated, it is increasingly apparent that consideration must be given to the possibility that the virus can remain airborne and enter the body directly. This has important implications for both the general public and for health workers. Recommendations about the use of masks and respirators are now in flux. The President has indicated that new guidance on masks will be released soon. Wearing masks is still about preventing the spread of the disease to those who don’t have it. Paper or cloth masks are still likely not effective for keeping the virus out, especially if airborne transmission is confirmed.

Daily COVID-19 Briefing: 3/28/20

Top news, reports and insights for today:

  1. America grapples with the staggering pace of exponential change
    The pace of change is nearly impossible to grasp. The rise in cases and deaths in the U.S. is doubling every 2-3 days. The three images below are taken from screen captures of the Johns Hopkins COVID-19 dashboard from February 29, March 9 and yesterday. We have not seen growth like this in an infectious disease outbreak in our lifetimes. This pace is likely to continue while some national leaders remain in a state of denial about what will unfold in the next few weeks. A new study posted online from the University of Washington’s Institute for Health Metrics and Evaluation (IHME) used a statistical model to forecast the demand for hospital and ICU beds. They anticipate the peak in demand will not occur until mid-April till the end of May depending on the state. A story in the Washington Post says that studies like this are being accused of being hoaxes intended to harm the President. Few expected the work of epidemiologists to be so politicized during an epidemic, but this shows that multiple narratives are playing out. The exponential pace of change is so bewildering that it is hard for experts to be heard. This will make it harder to maintain a commitment to social distancing in the near term.
  1. U.S. deaths jump a record 432 on Friday; New York, Louisiana and Michigan hit hard
    As the graph below shows, the number of daily deaths nearly doubled from 253 on Thursday to 432 on Friday. This puts the number of total U.S. COVID-19 deaths at 1,584, a 38% jump in one day. Hospitals in numerous hard-hit states struggle to keep up amidst shortages of basic PPEs, long hours, heavy caseloads and the fear of contracting the disease on the job (see today’s top pick). New York state, which now has a third of all U.S. deaths from COVID-19, recorded 134 new deaths (a 35% jump). But New York is not the only hot spot. Kentucky saw it’s first 4 deaths in one day as cases there begin to mount. Massachusetts saw a 129% rise in total deaths with 20 recorded on Friday. Louisiana continues to battle a surge in cases, with 36 new deaths in one day (a 43% jump). Florida saw its first day of double-digit deaths with 18 (a 63% increase). With the nation’s attention is focused on New York and Louisiana, Michigan has seen a spike in deaths, adding 32, and becoming the state with the 5th highest mortality count (92), which is now higher than California’s.
  1. Scapegoating begins as President announces he may impose ‘enforceable quarantine’ on New York, New Jersey and parts of Connecticut later today
    NBC News has just reported that President Trump announced today he is considering imposing an ‘enforceable quarantine’ on hard-hit areas including New York and sections of New Jersey and Connecticut. New York Governor Cuomo says the President didn’t mention this on an earlier phone call and does not know how such an order would be enforced. The federal government does have the power to impose binding quarantine in times of emergency, but that has rarely been done and any attempt to impose it now would surely lead to a court battle and widespread confusion. Meanwhile, the Florida governor announced that visitors from impacted areas must self-quarantine for 14 days when entering the state. Officials in Dare County North Carolina are setting up roadblocks to stop visitors from entering coastal beach communities.
    Why this matters? Throughout the history of epidemics, we have seen the frequent emergence of scapegoating. This involves blaming individuals, groups and communities for a health crisis. When people believe that things are spinning out of control, there is an impulse to search for someone to blame. Despite the evidence that the epidemic is moving freely throughout the nation, with hot spots breaking out in numerous places, the tendency to scapegoat particular regions where the epidemic is more advanced are likely to continue. This has potentially terrible consequences because internal travel restrictions are not likely to keep the epidemic from traveling and because such restrictions impose stigma on the hardest hit areas and make getting needed assistance and supplies to that area more difficult.