I have a Peanuts coffee cup which quotes the ever morose Charlie Brown as saying “Just when you think things can’t get worse, they get worse.” Los Angeles County is experiencing an unprecedented, asymptotic rise in cases (Figure 1 below). In one month, incident rates have gone from 12.54 new daily cases per 100,000 population to 45.14. The rise has been so dramatic that my trusty epidemic curve now needs a whole new axis, having blown past the previous July 14th high of 29.59. Don’t be reassured by the apparent flattening of the curve in the last week, no doubt there exists a tremendous backlog of cases from the Thanksgiving Holiday.
Deaths, too are rising (Figure 2). And, again, don’t be fooled by the apparent dip this week as reports are most likely delayed from the Holiday.
So here is what is strange – the last case I have seen in my clinic was on August 28th and we have tested hundreds of samples since that time. This is all the more perplexing because we experienced the same rise in cases in March/April and then the same July peak as the rest of Los Angeles (and the country). But I have not seen the increase in cases after Labor Day, the much maligned championships of the Lakers and Dodgers and the massive upswing we are now experiencing. So why is that?
First off, my practice does skew towards those that are older – about 30% of the practice are patients over the age of 65 years. And this is a group who are, undoubtedly, redoubling their precautions given higher risk and the very real prospect of a vaccine around the corner. When looking at LA County’s cumulative rates, those 18-49 years of age do contribute more cases relative to their total population. Those 65 years and above contribute fewer cases than would be proportionately expected from their population size (Link: http://dashboard.publichealth.lacounty.gov/covid19…/).
Location wise, the majority of patients in our clinic (based in Santa Monica) are from the Westside of Los Angeles. And while Santa Monica (274 cases per 100,000 population in the past 14 days) and Pacific Palisades (230.1 cases) are clearly visible on the LA Times’ plot of cases by neighborhood (Link: https://www.latimes.com/…/californi…/los-angeles-county/), these numbers are far lower than Athens Village (1490 cases) and Duarte (2213 cases).Los Angeles County has been non-communicative about the specific activities implicated in this current surge. A thorough search of their available data is essentially non-revealing, although their abysmal contact tracing percentages (60.3% in 7 days) would leave any data nearly useless because of missing information.
However, a recent study (Chang, S et a. Nature 2020: https://doi.org/10.1038/s41586-020-2923-3) of mobility networks based on cell phone data from 98 million US residents does give us significant insight into those setting which disproportionately drive additional infections. These are:
- Full service restaurants
- Gyms and fitness centers
- Cafes and snack bars
- Hotels and motels
- Limited service restaurants
- Religious organizations
- Physician offices
- Grocery stores