The idea of how and when our COVID19 pandemic will end is a big concern. A vaccine is at least a year away. There does not appear to be any “magic bullet” medicines at present. There are some promising studies underway but those take time. Time is something our healthcare systems do not have as they are being overrun.
This article builds on the research and work completed by W. Ridgway and a link to his presentation
In epidemiology we like to count things. We combine medical knowledge with public health data. We try and make predictions and good decisions. A lack of high-volume testing dramatically limits our data and thus, our ability to know what’s happening at present and what will happen in the future.
Looking at this morbid but important tracking method of COVID19 disease spread in communities allows us to explore several things. We are now able to have a simple formula to follow disease spread in the community based on prior knowledge of death rates. These death rates are carefully monitored and counted. Looking at deaths now gives us a window into how many in the community are likely disease carriers. Disease carriers will likely have immunity to the virus. That is currently under study but if SARS-CoV-2 behaves like other coronaviruses, there should be a period of immunity. This brings us to herd immunity.
Herd immunity is when enough people in the community have protection against the infection that it no longer spreads wildly. It’s a are thing to see an outbreak or cluster. Herd immunity begins when between 60-70% of the population has immunity.
Looking at this data, we can use death rate to give us an idea of how many in the community have had the SARS-CoV-2 virus. We can then use the death rate to monitor as we slowly expose the population, via relaxed social restrictions over a few days, to build herd immunity. Building herd immunity without overwhelming the healthcare system is critical. Sick people can go to the hospital for care. We can begin to care for those with disease other than COVID again.
I believe that a pulsatile fashion of loosening social restrictions for a few days, for certain individuals, then locking back down for a week or so will slowly build herd immunity. Medically fragile and elderly people should continue to stay at home. Avoiding that overwhelming burn through the community is the goal. That massive surge in patients is what overwhelms hospitals. Monitoring death rates is a tracking tool to follow and decide on when to re-tighten after the relaxation.
Get the report in PDF: COVID19 Regional Planning PDF