Today the US has almost 900,000 confirmed (this word is key) cases of CoVid 19. Below is the April 24, 2020 graph from Johns Hopkins Corona Virus Resource center. This picture can be summed up in one word: Overwhelmed. We’ve been given millions of words about this virus yet many are not offering clear evidence-based information for people of this country.
The US numbers continue to climb. So why is testing considered important in managing the progression of this aggressive virus? Two reason:
- We’ve no idea of the number of people who may be asymptomatic carriers of the virus
- COVID-19 is surprising in its aggressiveness
Test: How Many?
The US population is about 330 million people and to date we’ve tested 4,692,797. This is about 1.4 percent of the population. Obviously, a small percentage. Experts in the field of epidemiology explain the concept of Herd Immunity, when the immunity of a large number protect the remaining few that have not been infected. Vaccines have helped the world achieve Herd Immunity for many diseases in the past. But with COVID, we are far short of that goal. Germany set out with the target of testing 70 percent of their people and with that, are now slowly opening retail and other workplaces with specific guidance.
Testing allows us to identify asymptomatic people who carry the virus. Self-isolation and monitoring are a key step in slowing the spread. Those who test positive are likely to develop symptoms within 5+ days, and statistically most of those cases with be mild to moderate. If those people remain in the “at home” category eventually they will recover and have antibodies to the virus, building Herd Immunity.*
* One caveat on antibodies: scientists are not completely certain these antibodies will repel another round of infection from the virus.
This virus is significantly different from CoV1, (SARS) in that it resides in the upper respiratory tract. This allows it to spread easily compared to SARS, which inhabited the lower respiratory tract and lungs early on. SARS spread when people became symptomatic so they were isolated, usually in the hospital, quickly.
COVID 19 sits high in the respiratory tract so the cough and general malaise are early warning signs. What is emerging in the clinical reports of hospitalized people, as this article demonstrates New England Journal Of Medicine, is a very different aggressive attack, with blood clotting and lung changes in people without underlying diseases. The article from Washington Post includes a 3D model of CT scan of the lungs showing this phenomenon and underscoring that there are many unknowns with this virus.
Testing and Tracing is the mantra
Testing and tracing is the recommendation from Public Health organizations around the world. Many countries have used the “on the ground” approach to tracing to help isolate early, thereby slowing the progress of the disease. The charts and maps on the Johns Hopkins Corona Virus Resource Center provide daily updates of the global spread of the virus. Several countries used the testing and tracing approach and are managing a gradual return to business with continued monitoring.
This virus will not leave the world quickly or quietly. It is up to each one of us to follow stay-at-home orders, use social distancing, and practice exceptional hand washing all the time.