COVID 19: Shelter at Home. Yes, for how long??

Mar 18, 2020

The Harper Health team recommends that everyone perform at “Shelter at Home” strategy. As I mentioned in previous posts, aggressive quarantine measures can stem the tide of growth of the virus in communities. The difference between St. Louis and Philadelphia in the Spanish Flu epidemic of the early twentieth century is dramatic. We’re seeing the same level of impact in different areas of Italy. The shut down seems to be working there. We should be aiming to flatten the curve so our communities will have the resources to care for the sick.

The community of Harper Health can’t do it alone. It is my hope that Mayor Lightfoot follows the lead of London Breed, the mayor of San Francisco, and puts the city on lockdown. Yes, we’re much, much larger than SF, but we need to protect our citizens. If you’re not in Chicago, wherever you are I hope the same for your community. Does this mean that SF residents or cities on lockdown won’t get the virus? No. My hope is that during the time of social isolation and Shelter at Home we can:

  1. Build up supplies that are desperately needed. This includes SARS-CoV-2 testing, personal protective equipment for those on the front line, extra ventilators in the event of a local epidemic, and the trained staff to handle all of this

  2. Create a better and more comprehensive containment strategy. We’re learning that people can have the virus and be minimally symptomatic. That doesn’t mean they are minimally infectious. So, how do we identify people who are infected and isolate them from people at highest risk? Whom do we test? When do we test? How do we enforce isolation? Let’s figure this out

  3. Delay our community’s impact until a vaccine is available. This is unlikely since the first test of a vaccine began in Washington state a few days ago. It may take another year

  4. Develop successful treatments. The sacrifice of the early sufferers of this illness may be repaid in the novel treatments that are being studied. Whether it be something new such as remdesivir or something old, a malaria treatment called chloroquine, or an even older drug called thalidomide, there are really smart people on the case. If we give them time, there may be hope for future patients who get ill. PLEASE do not go out and buy chloroquine, thalidomide and remdesivir. Do not make them the new Charmin. We do not have outpatient protocols for any of these medications: who to treat, when to treat, how much to use, etc. Remember, 80% of folks who get infected (and probably more given the low testing rates) do well with just mild to moderate symptoms. Let the experts give guidance - we will keep up on the research. 

  5. Establish herd immunity. You may have heard of this concept before and I’ll try and explain it. In a population of people, once a certain number of people have gotten the disease and developed immunity, the virus no longer is able to find a susceptible host. Right now, no one has immunity to SARS-CoV-2, so if a person is susceptible and exposed, they’ll get infected. That person, if not properly isolated, will spread their infection to the R0 (R naught) number of people, for SARS-CoV-2 we think the R0 is somewhere around 2.3 (For Measles the R0 is 18!). With an R0 of 2.3, once 60% of the population develops immunity because they’ve been infected (or due to vaccination) the infected person has fewer potential people to spread it to. So, instead of the R0 being 2, it would now be lower. When the R0 drops below 1, any infection will die out.

In a simple model of an outbreak, each case infects two more, creating an exponential increase in disease. But once half the population is immune, an outbreak no longer grows in size. Image from:

So, one theory is to let the older adult population and those with existing illnesses hunker down and let the younger people get sick until 60% of the population gets immunity, and then the vulnerable population would be protected by herd immunity. This was an initial strategy that the UK was going to employ, but abandoned. Why? If the illness were relatively benign, this might be a good strategy. However, even young people can get really sick because no one has any protection against this virus. Even young people are dying. And if the rate of infection in the young, healthy population goes up too fast, we’ll overwhelm the system. Plus, there’s no guarantee that the young, healthy but now infected people don’t live with mom, dad, grandpa, Uncle Joe on dialysis, etc. leading these vulnerable people to be exposed, too.

That’s why we’re recommending a “Shelter at Home” strategy. Stay at home and severely limit your contact with other, potentially infected people. You can’t get sick if no one around you is sick. But the question remains, for how long? If everyone in SF (and in the Harper Health ecosystem) is at home and no one is getting infected then herd immunity can’t occur. Keep in mind, though, we actually don’t know how many people in SF and other communities are already infected and not yet symptomatic or have minimal symptoms. Maybe it’s a greater percentage than we know? Maybe we’re a bit further along in the herd immunity process? Probably not. In some ravaged communities in Washington state and New York this could be true, but are there walls around these communities?

The government of China built walls, though. (No, not that one.) In the Hubei province they shut everything down, kept people from coming in or going out, kept people in their homes, and the R0 in that community plummeted. They snuffed it out in that province. Is it possible that it could rage again in Shanghai or Beijing? Well, now China can employ a containment strategy, where infected people are quickly identified, tested and isolated, as are their contacts. If employed properly, an effective containment strategy can work until a vaccine is developed. It’s working in Singapore, Hong Kong and Taiwan.

Maybe we can learn from the Chinese here. In places where the infection rate and death rate is low, perhaps when the initial phase of illness passes and people poke their heads out of their apartments, the Trump Administration will have a containment strategy that can be applied to communities not yet hard hit by the illness. Perhaps.

So, unless something changes on the herd immunity front, and we don’t have a good containment strategy for after the current wave comes through, we will be holed up for a while. Between you and me, let’s just take this week by week.

And selfishly, our main focus is on you, the Harper Health community. If you all are in your bunkers as the bombs are going off outside, at least you’ll be safe.

So, stay at home, wash your hands frequently if you need to go out, and let us know if you have any questions or are feeling unwell.

More to come.

Dr. Will

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