Influenza vs COVID

I am seeing repeated claims that the death rate for our SARS CoV2 virus is not so bad, that we have been mislead. "Really, it is no worse than influenza." “What is the big deal?” “Did we really need to shut down society?” I have been trying to think about this critically and have dug into some of the published numbers. Here are some of my thoughts on the matter.

1. Influenza comparisons. I understand the desire to compare these two viruses. Influenza is the virus with which we are more familiar and with which we have a history of pandemics. The 1918 pandemic had a far higher mortality than what we are seeing now. These is no comparison. It was felt that 40 million people died world wide from that disease. Historians looking back on that pandemic theorize that the vast majority of deaths occured due to secondary bacterial infections. It was in the days before antibiotics. Likely, if that same disease were to strike again, much fewer would die due to our enhanced ability to fight those secondary infections effectively.

That said, the comparisons being made now are not with the pandemic years but with influenza from recent years. Overall, the mortality rate from influenza has improved markedly through the 1900's due to the factors stated above. Widespread use of the influenza vaccine began in the 1980's. Repeatedly, studies have consistently shown that the vaccines save lives. I spend a considerable amount of energy every year encouraging my patients to get vaccinated.

Three years ago, the vaccine that was developed was not a good match for the strain of influenza that hit our communities. It was a busy year. Our hospitals were full. I lost at least 10 patients that year, all of which were elderly. My colleagues had similar experiences. It was not usually a direct effect of the influenza but if someone was weak from other chronic conditions such as heart disease, lung disease, etc they weren't able to have enough reserves to recover. It was a hard year. My point is that influenza should be taken seriously also.

The COVID-19 disease is not the same disease. The potential for secondary infections is present but has not been seen nearly as much. The respiratory failure that we see comes as a toxic effects from the virus itself as well as an overactive immune response that is generated. Decompensation can be precipitous.

2. Death Rates. Yes, the published death rate from COVID-19 is decreasing. This comes as no surprise at all. In the beginning of our surge in this country our testing capability was extremely limited. Only the sickest patients were being checked. As such the death rate will appear artificially high. It is now estimated that up to 20% of those infected have no symptoms at all. The more we test, the larger the denominator and the lower the mortality rate will go. This does not diminish the number of patients that flooded the hospitals in New York and nearly overwhelmed their capacity. Death rate is not the same as total number of deaths. 

Our current mortality (death) rate in the US is 25.7/100,000 people. Belgium is the worse at 77/100,00. Two countries with some of the lowest rates are South Korea and Taiwan. Their rates are 0.5/100,00 and 0.03/100,000 respectively. That is a huge difference. It is interesting that neither country completely locked down their societies. What they did do was to aggressively test, contact trace and enforce strict isolation on positive results. China too has been aggressive.  Just yesterday it was reported that Wuhan had an “outbreak” of six new cases. The government response is to test 4 million people in that region. These countries show us the way out of our mess. Unfortunately, I fear that our inferior infrastructure and our unwillingness to give up civil liberties will hinder our ability to do so.

3. "Only the good die young." Death rates vary by age. In Italy, those above 90 years old with COVID had a 10% chance of dying. Those younger than 50 have a much lower rate of death. The number of deaths reflects how heavily a certain population is infected as well. In Bergamo Italy it is estimated that 66% of the entire population has been infected with the virus. It has taken a huge toll on their elderly population. Since such a large proportion of their population has been affected they are starting to develop "herd immunity" which protects those who have yet to be exposed. In New York City, by contrast, there have been many more infections in younger people. The reason is that their population is younger. Even with a low death rate the number is high because of the high number of people in that cohort. If New York’s population were older, their situation would be even worse. Both New York and Italy stand in stark contrast to other cities, such as Los Angeles, which is estimated to only have 2% of the population infected.

It does look like the death rate for COVID-19 is higher than influenza. It certainly has a higher capacity to cause critical illness.  Even if younger people live through their illness, they may need to be hospitalized and ventilated for weeks. Personally, though I am concerned for both influenza and COVID-19, if it is left to run rampant in high risk populations, SARS CoV2 has the potential to overrun our health care systems, overwhelm our public health workers and max out the morgues. Influenza hasn't done that for a very long time.

I do agree that we can’t stay in lock down forever. The bottom line is that we can and should relax restrictions safely. Ideally it should be done in the manner we have seen in Taiwan and South Korea. We must protect the most vulnerable. Nursing homes are especially dangerous places and we will need strict guidelines for isolation for a very long time. Multigenerational homes are another potential hazard. How families act that have children and grandparents living in the same place will be crucial. As we lift restrictions we must protect ourselves and all those around us by continuing to maintain a six foot radius, liberally cleansing our hands and using masks. These measures will help regardless of which infection we are dealing with.