One of the greatest threats to effective containment of an infectious disease is widespread underestimation of the disease itself. For coronavirus, this takes the form of equivalency claims between the virus and the seasonal flu.
Prior to community spread of this virus, when discussing risk assessment, public health officials stated that the seasonal flu was a greater threat to the American public. At the time, that was factual. Somehow comparisons related to risk of infection morphed into comparisons related to the disease itself. This is a dangerous progression. First let's look at why it's false; then we'll look at why it's risky.
How is coronavirus different from the flu? They are both upper respiratory infections. Both are caused by viruses. Medically, it may be easy to make a comparison between symptoms. In public health, however, the similarities essentially end there.
There are two key differences:
The basic epidemiology triad demonstrates that, for infectious disease to occur, you need an agent (coronavirus), a susceptible host (humans who are not immune to the virus), and an environment in which the agent can spread. Given enough time, infection will occur.
Over the last decade, the flu has produced an average of "9 million – 45 million illnesses, between 140,000 – 810,000 hospitalizations and between 12,000 – 61,000 deaths annually" (CDC Burden of Influenza). Compared to the coronavirus, those figures sound staggering. Tens of thousands of flu deaths make the current figure of a few dozen deaths from COVID-19 seem inconsequential.
Here's why public health officials are concerned. There are over 327 million people in the US. Each year, over 35-40% of American adults receive the flu vaccine, providing varying levels of immunity. Many more Americans have naturally occurring immunity to dominant strains of the flu because of prior infection. That only leaves about half of our citizens as susceptible hosts for the virus.
Nobody has immunity to COVID-19. There is no vaccine, not even a poor one. There is no population of individuals who have immunity from a previous infection. 100% of our population is susceptible. Anytime this happens, public health officials are concerned.
Infectious disease requires susceptible individuals for effective spread throughout a community. If someone with the flu heads out to a grocery store, only about half of their contacts are susceptible. That cuts the rate of transmission in half. When all of the contacts are susceptible, the number of individuals each infected person can infect is far larger. This allows a disease to rapidly spread throughout a community. We rely on a certain underlying level of immunity within a population to keep many infectious diseases from infecting the whole population.
The flu is not new. Over the last 8-10 decades, scientists have studied the best ways to reduce its spread, identify at-risk patients, and treat the condition. Pharmaceuticals, such as Tamiflu, are available. While we certainly have room for improvement, existing options are effective when used appropriately. Additionally, we've developed effective protocols for treatment utilizing advanced medical equipment to reduce mortality rates and to reduce the risk of long-term complications.
Most importantly, we have decades of knowledge about this virus. We know what its long term effects are. We know how long natural immunity lasts after infection. We know what warning signs to look for in a flu patient that may indicate they are more likely to have a severe case or experience complications. That knowledge forms the standard of care practiced at medical centers and hospitals around the world.
We have no such luxury with COVID-19. We are learning on the go, but do not have the luxury of time to test knowledge being generated during this outbreak sufficiently to meet scientific standards. We do not know how long immunity may last. We do not know whether or not someone can become reinfected a few months after surviving the virus. We do not know why children appear to be less likely to become infected and experience complications, or why adults with heart disease appear to be at the greatest risk. We do not yet even know if those current trends are real trends or simply what we have observed so far.
Medical history reveals that new infectious diseases are almost always more deadly than those we've experienced over time. This complete vulnerability combined with a lack of knowledge on prevention and treatment is a deadly combination.
We can expect the overall reproduction rate to decrease as containment measures are developed and herd immunity grows. We can expect the survival rate to improve as we develop better treatment strategies and identify treatments that save lives. But we can also expect those changes to occur after people have endured life-altering experiences and lost loved ones.
In epidemiology, people are data; data are people. Without data, we cannot conclude with any degree of certainty that preventive measures are effective or that treatment protocols actually work. Generating knowledge about containing infectious disease requires first experiencing the disease.
One of the greatest paradoxes of public health is that success often means unanswered questions are left on the table and the threat of widespread morbidity and mortality never manifests.
Successful containment of the coronavirus means that, like SARs and MERs, certain epidemiological questions go unanswered. Global infection never occurs. Widespread death was a mere whisper. The general public goes about their business as though nothing happened.
Successful containment of the virus would have meant that the flu was the greater threat facing our nation this spring. What constitutes the "greatest threat" can change depending on our success at containment. In early 2020, we were given months of advanced warning, allowing for preparation to fully contain the illness. That time has now passed.
Community spread is in the US. Our already failing system is being tested beyond its capacity. We do not know the extent of these effects as routine epidemiological protocols for infectious disease outbreak are not solidly in place across the country. But we have real-time examples across the globe of the pace at which this disease spreads and the effects it creates within communities and health systems.
This isn't the flu. 100% of American citizens are vulnerable (yes, even those who are not in the highest risk category of ages 60/70+), and we don't yet know how to effectively treat this disease. Therefore, the best solution is to take it seriously.
When the disease is highly contagious with an initial case fatality rate ranging from 10-60x that of the flu, public health officials need you to take it seriously.
Taking it seriously ≠ panicking. There's no need to stock up on hand sanitizers, toilet paper, or disinfecting wipes. Rather, encourage your leaders to take steps to protect your community. Wash your hands more frequently. And most importantly, place physical distance between yourself and others.
This may look like canceling in-person events, canceling vacations, and missing out on spring break activities. Many schools are embracing online platforms to reduce onsite classes. Reducing travel plays a big role. Our neighbors, loved ones, and perhaps even our own bodies will thank us.