On the eve of another mandatory stay at home order, with cases skyrocketing to new daily highs and ICUs reaching their breaking point here in Los Angeles County – an otherwise quiet Saturday seems to be a good day for some reflection.
In my Introduction to Epidemiology course (which I took in the Fall of 1993), we were presented with a standard epidemiologic curve which shows progression of illnesses in an outbreak over time. It looks something like Figure 1 below.
My professor wryly noted that it was best that an epidemiologist arrive as the outbreak was on its downward slope. This served two purposes – the first to ensure that the outbreak did not propagate further and,the second, to make it appear as if you had actually done something. In fact, for many outbreaks, they would have tapered off on their own.
The epidemic curve of COVID-19 in Los Angeles County today looks like this:
So by this point in time, we’ve had a couple of go rounds at this epidemic. From the first wave, to the mid-July surge and now in the current mess we find ourselves – far outpacing our prior peaks. So what have we done wrong? Why are we not learning anything?
The first shelter-in-place order occurred on 3/23/2020 when the new daily case rate was – wait for it – 2.29. Restrictions were lifted on 6/12/2020 when the rate was 12.86. Does anybody notice a problem already? Cases increased 6 fold but we’ve decided to go ahead and open up.
Statewide closure of all indoor activities occurred on 7/13/2020 when the case rate had (predictably) risen to 29.59. Closure of gyms, indoor dining, bars, movie theaters, and museums was re-imposed, this after most indoor businesses, including bars, restaurants, wineries, and movie theaters had already been shut down two weeks earlier. Case rates began to decline thereafter.
On 8/28/2020, Governor Newsom unveiled a new set of guidelines for lifting restrictions, titled a “Blueprint for a Safer Economy” and cases were down to 11.95 ultimately dropping to a new low of 7.8 the week of 9/8/2020
On 10/1/2020 Los Angeles County Public Health announced their timeline for sector reopenings within the rubric of the Governor’s blueprint. Except by that point, our case rates had crept back up to 9.61 and, you guess it,, rose even further as restrictions were loosened making a steady upward march and then a rocket-like acceleration to the current rate of 45.14.
All I have done so far is describe what has happened in Los Angeles, without going into any of the details of sector restrictions or the myriad of questions that ensue. Questions like: If nail salons can be open, how full can they be? Can we dine indoors or outdoors or only have take out? Are parks opened or closed? Can we go to the beach? Can we hike? Can I work out with a trainer outdoors? Can I take an indoors exercise class? Can I go to choir practice? Can I practice my faith indoors or outdoors? Drive in movies? What about trick or treating? Basketball? Tennis? Swimming? Griffith Observatory? Are golf courses open? Can I go bowling? Is the entertainment industry an essential business? Do I need to disinfect my groceries? Can I go to the farmers market? Can I visit my neighbors in their home? In their backyard? Can my kids go back to school? Can I have a drink at my local bar? Can I go dancing? Are preschools open? Can I visit a family member in the hospital? In a skilled nursing facility? In a residential care facility?
Let’s break this down as if we were students in a first year epidemiology course… not only does it matter what you do, it matters when you do it.
You can ask a paragraph of specific questions or you can leave the public with the simple truth – your risk of becoming infected with COVID-19 is a function of three factors: prevalence, proximity and duration. The more people infected in the population – the more likely you are to catch it. The closer you are to an infected individual – the more likely you are to catch it. The longer you are around an infected individual – the more likely you are to catch it.
At every single point we ‘reopened’ the County, cases were rising. So the specifics of what we did were overridden by ill considered timing. The same way that a rising tide lifts all boats, a rising prevalence rate increases your chances of becoming infected. We reopened into the tide of rising cases in June and again in October. When we have closed, we never had the patience to stay closed or never had the capacity to identify and shut down specific locations of where cases were transmitting, even at a low level. When we had COVID-19 pinned down in September, we all went away for Labor Day holiday and spread the smoldering embers around again.
So, to our public health officials, this isn’t rocket science. You want to show up and do something, anything, when cases are decreasing. You want to keep people away from one another and, if that is not feasible, limit the time that they interact. If you cannot limit the time that they interact (say like in their place of employment), then you need to provide them with daily testing. If people need to eat, they need to do so by taking their food away from the establishment that serves it. If people need to party, they should do so outdoors. If they need to sing, they can sing in the shower.
The public instead has been worn down by the minutiae of how many households can gather in an empty field and the nonsensical closure of parks and outdoor recreational facilities. Quite frankly, we don’t have the stamina for it anymore.
So practically, what can you as an individual do to limit your risk as we stagger towards a vaccine? It’s a simple three part answer.
- Know the population prevalence. You can’t do much to influence this other than not becoming part of the problem. With case rates hitting historic highs, that should be a cue to be even more vigilant than before. If you’re asking yourself “is it too much that I am spraying the groceries I have delivered with 10% bleach?” – right now, it’s probably not a bad idea and it certainly can’t hurt.
- Proximity. How close am I to people I don’t know? If the guy behind you in Peet’s seems a bit too close for comfort, tell him to back off. Better yet, make your coffee at home.
- Duration. Am I in an enclosed space or in a situation where I cannot physically distance for a long time? Honestly, I’d be thinking in seconds rather than minutes. Can I be out of here in 30 seconds? For what it is worth, I don’t ride the elevator at work. If you need to shop at a grocery store, be sure to keep moving while you are there – grab what you need and move on. Preferably stores should have a one way pathway through the store. If not, shop elsewhere.
Prevalence, Proximity and Duration. Everything else is just window dressing.
That’s the blog post.