Beware the Siren Song

 

"First you will come to the Sirens who enchant all who come near them. If anyone unwarily draws in too close and hears the singing of the Sirens, his wife and children will never welcome him home again, for they sit in a green field and warble him to death with the sweetness of their song." – Homer, The Odyssey

Ulysses was a reluctant but skillful warrior, condemned to command a sea voyage of uncertain outcome and duration. Among his challenges was an encounter with the Sirens. In calm summer seas, the sweet, irresistible song of the Sirens lured sailors causing them to dash their ships upon the rocks.

Fortunately for Ulysses, he had advanced warning of this danger, and took the sensible precaution of packing the ears of his crew with wax and ordering them to lash him securely to the mast. Like Ulysses, we are reluctant warriors in this SARS-CoV-2 battle. We are on a journey of unknown duration. Who are our Sirens?

Our COVID-19 numbers look very good, directionally the same as I reviewed last week. Our effective reproduction rate has been less than 1.0 (virus is receding) for 20 days. New cases have dipped into the 200s and approaching levels we have not seen since last April. Test positivity rate (rough prevalence estimate) has been below 5% for three weeks. New hospitalizations are trending down, albeit more slowly than I would like. We saw no Labor Day surge. Good, good, good.

We appear to be sailing on calm seas. So why do we keep hearing from so many masking and distancing nags (myself included)? Because even though things appear to be going well now – and they are – we must remain wary of our Sirens:

• Unawareness of the experience in the global community. We have recently seen a recurrent scenario play out across the world. Early in the pandemic, a city/region/country took decisive action, achieved excellent viral control, and received accolades as a model for other to follow. Recently, as those communities have started to reopen, they have seen the virus come surging back, and have been forced to re-impose substantial economic shutdowns. A common root cause of the resurgence: indoor aggregation of people in bars, and is some cases, social gatherings in homes. To replow old ground – the nature of this virus has not changed. If we let down our guard, fail to mask and distance, begin to return to crowded environments, we will see a COVID-19 resurgence. It is worth spending some time reading about the experience of others - Quebec, Israel, London, Marseilles to name a few. All the reporting highlights on how dispiriting this experience has been to people in those communities. Having lived through one major surge in Houston – having seen the health, societal and economic impact of our surge – I think most would join me in my desire to avoid another COVID-19 crisis.

• Failure to appreciate the stealthy nature of exponential growth. Our new cases in Houston look good. Hospitalizations are flat. Why worry? Because in an immunologically naïve community – absent masking and distancing – disease will spread exponentially, and this growth is insidious early on. Here is an easy means of explaining exponential growth to others, with minimal math (you do need to multiply). Assume you have an effective R-value of 2.0. One individual will, on average, infect two others (1X2=2). Those two, in turn, will infect two others (2X2=4). It helps to get a piece of paper and write this down:
  -- 1st doubling 1X2=2
  -- 2nd doubling 2X2=4
  -- 3rd doubling 2X4=8
  etc., etc.

Continue this for a total of 10 cycles, and your answer should be 1024.

So, if you look at your numbers for each doubling, early on it does not look like a big deal. Two becomes 4, 4 becomes 8. But by the 10th doubling, 512 becomes 1024, and it feels like it is exploding. That is the nature of exponential growth – it starts slow, and accelerates. It is easy to find comfort in the early part of the growth curve; by the time the steep part is apparent, the infectious horse is out of the barn. It is too late to contain.

We should be encouraged by our current flat/declining numbers – as Quebec was – but not be lulled into complacency.

• Hope we are at or approaching "herd immunity." Herd immunity is the point at which enough of the population is immune that it becomes difficult for the virus to spread. If an infected individual walks into a place of worship, school or restaurant, and no one is immune to the virus, it will spread easily to others.

On the other hand, if many or most already have immunity, the virus has difficulty finding someone to infect, and it fades for lack of new hosts (as an aside, this effect can be mimicked by effective masking and distancing). No one is sure what percentage of the population needs to have immunity to achieve this effect, but most estimates I have seen are between 50-70%. Part of the ultimate goal of vaccination is to produce herd immunity, without a lot of people actually developing the disease.

Again, let us do some simple math.

For the purposes of this exercise, I am going to make very optimistic assumptions. Reality is probably worse.

There are approximately 325 million people in the U.S. Let us assume individuals under 18 (about 75 million) cannot be infected, nor spread the virus. This is not a valid assumption, but we are being optimistic. That leaves us with a "herd" of 250 million people. If we assume the lower end of the range to reach herd immunity – 50% – 125 million people would need to be infected. The mortality rate for COVID-19 is in the range of 0.5-1.0%. We will assume the more optimistic 0.5% rate. At that rate, infection of 125 million people would result in 625,000 deaths – about three times the number of all Americans that have died so far.

There is an active debate among thoughtful and intelligent people regarding at what level we will achieve herd immunity. For an example, refer to a recent article from The Atlantic. Theories abound regarding factors that may drive the herd immunity percentage down: differential susceptibility of sub-populations, chaos theory, differential importance of cellular immunity. Perhaps our trigger is lower.

Our Siren here is the word "perhaps." However valid the theories, they are still theories and belie some actual observations of spread that occurred early in the pandemic, such as on the Diamond Princess cruise ship. Personally, I am not willing to accept the risk of larger scale death or disability when the alternative is simple – mask and distance as a bridge to the vaccine. Availability and use of an effective and safe vaccine will ensure protection, and so poses the best long-term strategy. 

Houston should pause for a moment of self-congratulation. We have pulled together as a community and done a very effective job combating SARS-CoV-2. We are in a position to begin to relax restrictions, and to incrementally resume more of our prior activities. We must all maintain our attention to proven viral control practices – masking, distancing, avoiding aggregation in crowds. We need to be thoughtful about our community priorities (I would vote for reopening schools successfully before bars).

It is time to lash ourselves to our mast, resist the allure of the Siren's song, and sail on to the end of this pandemic.

What if this is as good as it gets?

Many of you will recognize this as a movie quote. In the 1997 film “As Good as It Gets,” Jack Nicholson plays Melvin Udall, a neurotic, misanthropic character with obsessive-compulsive disorder. Early in the movie , he poses this question to a waiting room full of patients in his psychiatrist’s office.

This has been another week of good news. Our community numbers continue to improve. It looks as if we largely avoided a post-Labor Day surge. Texas Gov. Greg Abbott signed an executive order relaxing restrictions on certain services and businesses. It feels like it is time to reopen a bit.

But there is always a “but.” What about flu season? School reopening? Cold weather promoting viral spread by driving people indoors? Plenty of other nations (recently Israel, France, and the UK among others) seemed to have things well in hand, only to see second waves emerge and drive the return of restrictions. Why does our good news always need to be tempered with a warning to keep looking over our shoulder? What if this is as good as it gets?

The Houston regional numbers are unequivocally positive this week. Our calculated R(t) has been below 1.0 (virus is receding) for almost two weeks. New community cases dipped below 500 for the first time in months (our goal is less than 200 per day), and the Texas Department of State Health Services (DSHS) seems to be making real progress in correcting its well-publicized problems in reporting these data points in a timely and consistent manner. The test positivity rate for TMC-affiliated labs is 3.2%, well below our 5% goal (however, city and county positivity rates are running 4-5% higher than the TMC).

Although we ideally would like to see new admissions to TMC-affiliated hospitals declining, they are flat, and still 60% higher than the nadir in May; the fact they are not increasing is relatively good news. Moreover, hospital length of stay has improved to the point that more COVID-19 patients are being discharged than admitted, so hospital census of these patients continues to drift downward. We have ample hospital capacity. (If these monitoring concepts are unfamiliar to you, I recommend you review my prior messages).

Perhaps the best news of all, none of the numbers above reflect any Labor Day impact (although theoretically it still could still show up later this week). Thank you Houston: Masking, distancing, avoiding aggregating in crowds – it works. We cannot eradicate the virus, but we have shown we can slow its spread and decrease community viral prevelence.

The big news last week was a relaxation of restrictions in Texas. I would encourage you to read Governor Abbot’s executive order. In brief, Texas businesses, including restaurants, can operate at 75% of their total listed occupancy, including restaurants. Hair salons, barbershops, massage parlors and other personal care service businesses have no occupancy restrictions as long as their workstations are spaced at least six feet apart. Outdoor gatherings of more than 10 people still require approval of city or county government.

We want to avoid reliving our May reopening experience, which led to a very large June/July surge. Reasonable people may respectfully disagree on whether the new executive order goes too far, or not far enough. Thankfully, Houston still seems to be populated by mostly reasonable people. Those who believe the virus must be maximally controlled to avoid preventable death probably think it goes too far. Those who are concerned about protecting the economic livelihood of members of our community probably think it does not go far enough. On balance, the order is a logical, reasonable next step. It is not perfect, but perfect recommendations in the midst of a novel crisis are not a realistic expectation.

At the end of the day, keeping the viral prevelence low in Houston depends on most of the metroplex’s 7 million inhabitants making good daily decisions.

Last week I visited my father, whom I had not seen since the pre-COVID era. I drove back through the outer bands of Hurricane Sally, managing to skirt most of it. For the majority of the trip, the law mandated I keep my speed below 70 mph, and I set my cruise control at 76. However, when the rain came down hard, and my visibility was limited, I sensibly disengaged the cruise control and slowed down – not because this was mandated by regulation, but because I had appropriate situational awareness, and I was concerned about my safety, as well as the safety of my wife and others on the road.

So it is with our collaborative control of COVID-19 – we must maintain situational awareness to protect the health and safety of our family, friends and neighbors. I still think one of the best pieces of advice I have heard during this whole crisis came from Dr. Klotman very early in Houston’s pandemic experience: If you walk into a business/public gathering, and it feels like business as usual, turn around and walk out. It is probably not safe. Wherever people are aggregating, sincere efforts at appropriate distancing should be visible.

With Dr. Klotman’s advice in mind, as we start to relax restrictions, what are the pressure points to which you should remain alert? When do you need to take off the cruise control and slow down? A few thoughts, which reflect my opinion.

• Belief that this is “over” because the hospitals are not in danger of being overwhelmed. Gov. Abbott’s order has a safety valve built in: Reopening should not proceed if more than 15% of hospital capacity is consumed by patients with COVID-19. Currently TMC facilities are at about 6%, so we are in great shape. However, this is not the ideal metric, as it is a lagging indicator. Just like the patients with nascent heart disease who puts off preventive treatment and lifestyle changes until they experience a major heart attack, by the time our hospitals are filling up, it is too late. At that point we are already surging, and will continue to do so for weeks. A better leading indicator would be new community case numbers, but as we have discussed at length, this measure is still fraught with – improving – data reporting issues.

Tantalizingly, Baylor researchers are doing some fascinating work quantifying the presence of virus in wastewater. It appears virus in the upper respiratory tract is swallowed, and much of its antigenic material survives digestion and can be detected in human waste. If this pans out, it could provide a method to monitor a neighborhood, office building, dormitory, prison or nursing home by sampling wastewater. Preliminary data indicate we may be able to detect an increase in viral prevalence in advance of symptom development. A true leading indicator.

Advice: Do not get comfortable focusing on a signal metric – reading the speed limit signs alone is not enough.

• Settings with no capacity limits. The governor’s order allows a number of entities to operate at 100% capacity. Churches and places of worship are explicitly excluded from occupancy limits. As noted above, certain services (e.g. hair salons, barbershops) are able to function at full capacity if spaced appropriately. I am confident most (but not all) organizations will act responsibly and safely.

Advice: Ask yourself some key questions. Does this feel safe? Are others masked appropriately? Is my exposure to people outside of my household closer than six feet, and more prolonged than 15 minutes? Specific to houses of worship, keep in mind singing has been clearly established as a means of transmission, and probably results in spread of virus beyond the now famous six-foot limit. Also, avoid congregating before and after services.

• Bars. First of all, I want to stop to acknowledge the hardship the pandemic has placed on bar owners, who are mainly small, independent businesspeople trying to preserve their livelihood. Many have suffered major financial setbacks during this time, probably few more so than those running bars.

However, there is a reason bars have largely been closed. Congregating a high density of people in a contained indoor environment for extended periods of time with inconsistent mask usage is a perfect set up for viral spread. Add a little alcohol-induced social disinhibition, and viral spread is highly likely. Some establishments have creatively leveraged their food services to allow for table service (by order, at least 51% of sales must be attributable to food). But regardless of whether it is a “bar” or “restaurant,” a crowded indoor space is a crowded indoor space.

Advice: Ask Dr. Klotman’s question. Does this feel like business as usual? If the answer is yes – if there is not real evidence of compliance with good distancing practice – it is probably not safe.

So is this as good as it gets? Perhaps, but that is not necessarily a bad thing. Nicholson’s Melvin Udall was not “cured” of his neuroses, but he found meaning in human connection. We can continue to reclaim our lives, cautiously expand our economic activity, return to school, etc., if we all band together, maintain situational awareness and continue doing what we have proven works: Mask, distance, be wary of crowds – a reasonable price to pay to resume our lives while protecting each other.

 

(Note:  Between June 2020 through November 2021, I wrote weekly COVID-19 pandemic updates seen through the lens of a health sciences university.  My intent was to provide reliable information, acknowledge legitimate concerns, console, and encourage.  Each posting reflects issues our community was experiencing at that moment in time.  I have reproduced selected examples on this site).