San Antonio Update, 7/12/20
In which I try to give context to Dashboard Data. This is going to be a data dump, so pick your topic and follow along. All data are for Bexar County only.
Epi Curve
We see the daily case reports. Since early June, daily case counts have been up dramatically. Due to backlogs from the labs and delay in reporting, noting the day of report can be misleading.
As you can see in the graph below, the daily lab reports are all over the place. So a drop one day or even over a few days can give a false sense of security. Due to the fluctuation in lab reports, we’ll use the 21 day average, as shown by the red line. Cases are continuing to increase, even if we have a drop for a few days.
This is because the more people are infected, the more people will get infected. Yes, that seems obvious, but is easy to forget. It’s why the numbers increase exponentially. This graphs tells us where we are today.
The graph below helps us to determine where we’ve been. This uses data from the first day a person developed symptoms or the date they were tested. Knowing this helps us to determine a likely exposure date. While the graph above shows numbers starting to jump consistently around June 7–9, the graph below shows that the increase really started around June 1st or 2nd. Given the median 5-day incubation period, that means that the exposures leading to this increase were most likely around may 25–27. It’s not precise, we work on estimates, but this information helps us to predict future spikes.
Alas, it also looks like cases are dropping, which we know is not true from the above graph. These data are inputted after the fact. A lab report that arrives today and gets counted today, could be added to the following graph for 2 weeks prior. That’s why it doesn’t go all the way until today, we don’t have complete data for the past 1–2 weeks yet. The red line again shows the 21 day average, which suggests a continued increase.
Who is getting infected?
Young people, mostly. We’ve heard that this is a disease of the elderly and health-compromised. And the worst outcomes typically happen in those groups, but that doesn’t meant the young and healthy aren’t affected (or infected).
The above graph shows the percent of cases in each group. The black bar is the percentage of people in Bexar County who fall into that age group. Unfortunately we don’t have disaggregated data for 0–19, so can’t say if those are small kids or teens. What we do know, is that since May 1, cases in people under 20 have increased dramatically.
People aged 20–60 form a disproportionate number of cases. That is, a higher percentage of people in that age group have COVID than exist in our population. As cases continue to rise in the younger population, cases in the older population continue to fall. That’s hopeful, since they’re the most likely to have complications. That could be because older people are taking more precautions to limit exposure. Unfortunately, many still see their children and grandchildren who are infected.
The graph below is another way of looking at the above data. For each month, you can see the percent of new cases in each group. So, in May, less than 10% of new cases were in 0–19 year olds.But in the past 10 days, almost 15% have been in that age group.
Is there a Racial/Ethnic Disparity?
Yes. Again, the black bar represents the percent of people in that group in our population. The orange bar reflects the proportion of cases for each group since the beginning of the pandemic. As of 7/11/20, if you’re white, you’re far less likely to be infected. The infection rate in the Black and Asian populations are just under the overall percentage in the community. However Hispanics, who make up 60% of the Bexar county population make up 75% of the cases and 33% of the deaths. We don’t have a breakdown of age and race/ethnicity.
The case-fatality rate is still highest in the Black community. It’s possible that many of the Hispanic cases are younger, because the survival rate for children and young adults is higher and that more elderly Black/African Americans are getting infected. But we don’t have the data to show that for sure. We also don’t know who is getting tested.
We do know that of the new cases each month, most have been in the Hispanic community. Fewer Black/African-American and White residents are being reported to have COVID. Again, we don’t know if that is a bias in testing. The Asian and Native American populations do have cases, but very small populations in San Antonio and case numbers have remained fairly low and consistent so far. However, it’s important to note that an outbreak in such populations could be easily overlooked because the initial numbers are small compared to the rest of the county. We need to pay close attention to all populations.
Are we testing enough?
The rate of positive tests is one of the indicators we use. If we’re testing a broad cross-section of the population, including asymptomatics and pre-symptomatics, we expect a relatively low positive test rate. If we are only testing those who are very sick, we expect a high positive rate. Throughout June the rate of positivity was already increasing.
In addition to diagnostics, the goal of testing is to identify those who are infected and isolate them immediately, ideally before they’re contagious. The other goal is to identify their contacts before that group is contagious. The percent of people testing positive is increasing because there is more COVID out there.
How sick are people getting?
Very. Hospitals are nearing capacity. The blue bars here show the percent of cases hospitalized. In May, we generally stayed under 8% of people being sick enough to require hospitalization. Since June, that percent has increased to as high as 14%. So we’re not just seeing more hospitalizations because we have more cases, the percent of people who are very sick is increasing as well. The orange line shows the current number of hospitalized cases. This is as important as the rate, because this is what we look at to know our capacity.
Who is getting hospitalized?
It’s not just the elderly. These data are from the month of June. The black bar again shows the percent of people in the population for each age group. The grey bar shows the percent of hospitalizations for each age group.
If you’re “young and healthy,” we would expect all the other bars to be lower than the black bar. That holds true for those under 40.
A critical factor in our overall hospital capacity is availability of staffed ICU beds. These data are current as of July 11. Generally, if you’re under 40, you’re less likely to be in ICU, less likely to require a ventilator, and less likely to die. Once you hit 40, you may still have a better chance of survival but may have to spend time in ICU or on a ventilator, and long term recovery is more challenging.
Phew! Right? I mean, if you’re young and healthy.
Hold on. Let’s look at the yellow bar in the graph below. That is the percent of hospitalizations with NO co-morbidities in the month of June. During that month, more than 60% of the hospitalizations for the under 20 and almost 50% of 20–29 year olds were in those with NO underlying conditions. You’re still more likely to die if you’re over 40. But that doesn’t mean you escape serious illness. And being healthy may help you survive long term, but you still risk hospitalization and serious consequences.
Is it all doom and gloom?
Well, it’s pretty bad right now. The risk of something really bad happening is higher when hospitals are full. Even if you don’t need a hospital for COVID, you could have a car accident and have nowhere to be treated because ERs are full. Or appendicitis, or any number of “usual” ailments.
But we’re not just tired of quarantine. Humans crave social contact. We need each other. That’s not a bad thing. But we need to be creative and re-think HOW we interact. The Population Health Advisory Committee offered ways to gather without increasing risks. I’ve written about risk-reduction In The Time Of COVID.
We need to start practicing #SafeSix (thanks to Atlanta Beltline for that one). Stay six feet or more apart.
Limit groups to a few friends practicing the same guidelines. Don’t be afraid to ask others if they’re practicing the same steps:
“If you really want to make sure your partner uses a condom, you have to express why it’s important to you and why it’s aligned with your values and why that’s something that you need from them,” says Julia Feldman, who runs the sex education consultancy Giving the Talk. Similarly, she says, “If you want your mom to wear a mask when you see her, you need to explain why it’s important to you and why it’s aligned with your values.”
#MaskUp
All data taken from the City of San Antonio’s Dashboard.
