In planning our recovery from COVID-19, one of the most important things we need to do is learn from the painful and extremely expensive lessons of this pandemic. We need to not underestimate COVID-19 and not mistake it for the flu. COVID-19 is no flu. It is a SARS (severe acute respiratory syndrome) virus, and is much more dangerous. In two months, COVID-19 has killed nearly three times as many people as the flu killed all last year.

I emphasize this because I have heard reputable people recently saying that the virus is just another flu and not as dangerous as previously thought because the case fatality rate appears to be less than expected (“The politics of fear overwhelming us today,” Star-Advertiser, Island Voices, May 19). But this is a dangerous mistake. The case fatality rate appears to be going down simply because more people are being tested and not because the virus is less deadly.

According to the U.S. Centers for Disease Control and Prevention: Last year, in the entire last year, there were 34,200 U.S. deaths from the flu. In just the past two months alone, COVID-19 has killed more than 90,000 people in the U.S. This is with mitigating factors in place.

So how could the case-fatality rate be less than expected but have such a stunning death curve? This is because case-fatality is only one factor that makes a virus dangerous. The other major factor is how contagious it is. This is described with a contagion rating called an R0 (“R-naught”) number or “reproductive number,” which describes how contagious it is. It is a number that represents how many people will be infected by an average infected person during their infectious period.

The CDC reports that COVID19 has an R0 number of 5.7 — much more contagious than the flu, which is rated at 1.3. So we have to understand that the danger posed by a virus is not just its case-fatality rate. It is multiplied by the number of cases, which is determined by the R0 contagion rate. The reason we engage in mitigating factors is to lower the contagion rate or R0 number. In other words, the reason we wash our hands, wear masks, stay at home, and keep physical distancing and quarantine, is to lower the contagion rate. This reduces the number of people that an infected person will transmit the virus to, and thus the contagion rate will go down. If we can reduce the R0 number to below 1, the epidemic will gradually disappear.

This is how the mitigation measures flatten or “bend the curve.” We absolutely need to open the economy because a prolonged shutdown will also cause death and despair. However, if we don’t take seriously mitigation measures to reduce the contagiousness of COVID-19, the death rate will go up again and slow our recovery.

Please see the simple explanation in my short youtube video, “Don’t Make This Mistake,” at www.AskDrShintani.com. In this way, people will understand why, when we reopen business, it is still important to observe the mitigating measures suggested by the CDC and local authorities.

Let’s be akamai, and not make the deadly mistake of underestimating COVID-19.