This appears to be the “over the hump” week for much of the World. This is not a single global epidemic, but a series of linked regional epidemics. Each region is affected differently based on multiple factors including:
- The number of infected individuals initially entering the area
- The demographics of the region especially including age and common diseases
- The degree to which social distancing and other measures were put in place and the timing of their implementation
It is increasingly appearing that the primary affect of the various control measures has been to limit the height of the peak of deaths and resource requirements, but has had less effect on the overall duration. In other words, it does not appear to have pancaked the curve, just simply lowered it. Right now, most places are at about the half way point for deaths and a couple weeks past the half way point for new infections.
- Just about everywhere has seen about a 3 week run up in number of deaths to the peak, and it’s looking like this will be followed by about a 3-4 week decrease back to near baseline.
- The biggest concern is since the peak number of cases was not as high as in an unmanaged epidemic, will this be enough to keep from having a resurgence in the future.
Much of the world is turning to how to reopen their economies without creating a second wave of infections and deaths. In many circles, this has been termed to moving from “the hammer” to “the dance.”
The hammer was the relatively blunt instrument of more or less heavily restricting interpersonal contacts through mandated closures and placing “stay-home” orders. The dance is aptly named because it will involve a period of forwards and backwards adjustments in these social distancing guidelines. The keys, however are straightforward:
- Wait until the incidence of new cases is small enough to manage
- This is the biggest importance of serology testing: What is the true rate of infection in the community. We simply do not know this yet.
- Keep the rate of new infections low enough that classical public health measures can be used to limit the spread. These measures include:
- Ways to rapidly and effectively identify almost every new case. This means both educating the populace and having easily accessible rapid testing for the presence of virus – which some areas, including most of Asia, and some of Europe have, but other parts of Europe and most of the US do not.
- An adequate public health workforce, combined with workplace policies and guidance to effectively identify and manage close contacts of infected individuals so as to decrease the chance they have transmitted to someone else.
This is a tight window. Since the average time from infection to symptoms is 5 days, and a person appears to be infectious for 2 days before symptoms develop, that means that to be effective, same day test results are critical to be able to identify and quarantine the next link in the chain before they become infectious.
- Person 1 infected on day 0; develops symptoms on day 5
- They were infectious on day 3
- Person 2 infected on day 3; would develop symptoms on day 8
- They were infectious 2 days before that on day 6.
- If person 1 gets tested on day 5, person 2 needs to be identified by the next day to minimize chance of continuing the chain.
Have confidence that the existing healthcare system is adequately robust to handle any upticks in the number of cases as social distancing measures are dialed back.With this in mind, both World Health and CDC are looking at communities in three broad groups:
- Low mitigation requirements: Communities that never had major circulation or have nearly eliminated community circulation. As their peak passes, and the measures just reviewed are accounted form these communities can decrease protective measures. This process will start in the next couple of weeks in some areas
- Medium mitigation requirements: Former hot spots that have infections on on a downward trend and capturing most new cases. This will be rolling, likely beginning in June and will include removing stay-home orders and reopening in a rolling manner:
- Retail and food service
- Schools (although likely leave schools closed through the summer)
- Significant mitigation requirements: Anywhere cases are not being controlled or that do not have adequate healthcare resources to handle inevitable blips in cases.
- Stay at or return to “the hammer”
In all of these categories, prevention measures will have to continue until enough members of the community are immune to the disease through either exposure or immunization. Prevention measures include:
- Social distancing
- Potentially limits on inter-regional and international travel especially between different transmission categories. This is all called the dance, because communities may need to change categories a few times until we have the adequate community immunity established.
- Workplace, shopping area, and public transportation population density limits. This means continued encouragement of:
- Shift working
- Limitation on face to face meetings / conferences