Why are people freaking out about Covid-19 more than flu?
Each person infected with seasonal influenza may infect approximately 1.3 other people. For SARS-CoV-2 (the virus that causes Covid-19), it is estimated to infect about three times as many people (estimated at two to four). This number is called the reproductive factor — or R0, sometimes pronounced “R-naught” — and you may see it referred to that way. A higher reproductive factor means Covid-19 will lead to many, many more cases very quickly and may overwhelm an already burdened medical system.
Even if you are not at high risk yourself, we still all have a public health obligation to take interventions that will prevent its spread.
Why should I even care if I get it? It doesn’t seem that lethal.
It’s true that for healthy people under age 50, it’s not especially lethal — the mortality rate is quite low, though still up to 20 times higher than flu. But it becomes more lethal for older patients. The chart below gives good estimates for mortality rate by age bracket compared to flu.
The WHO estimates an average mortality rate of 3.4%, which is around 100 times higher than flu — but do note that average is across age brackets.
Current evidence suggests that the fatality rate from Covid-19 ranges from 9% to 19% for older individuals, as well as for people with conditions such as cardiovascular disease, diabetes, and cancer and those who are immunocompromised.
Even if you are not at high risk yourself, we still all have a public health obligation to take interventions that will prevent spread that could overwhelm the health care system, as is happening now in Italy.
In case it occurs, what do I do?
Don’t be the person who takes up medical resources that someone else needs more than you do. This is our ethical North Star with this disease. The goal should be to minimize spread so that as health resources (diagnostics, treatments, ventilators, oxygen concentrators, etc.) are needed, they are available to the people who need them most. The graphic below explains exactly why this is important.
If we can slow down the spread, we have more time to react and make the necessary preparations. A slower spread will save many lives because an overwhelmed health care system will not be able to provide care to all who need it.
Health care experts call this “flattening the curve,” and it’s perhaps our best and only strategy for mitigating this situation.
The issue isn’t the lethality of Covid-19 as much as the overall impact of the outbreak. While these other diseases may be more lethal, the combination of reproductive factor (R0), receptivity in the population (susceptibility), and immunity may make them much more manageable. SARS-CoV-2 (the virus that causes Covid-19) is totally new to the population, so no one is immune.
Each year, people are already immune to the flu because of exposure to prior variants or because of annual vaccination. There is no vaccine available yet for SARS-CoV-2.
We should expect it will be at least Q1 2021 before a tested vaccine is widely available. In the meantime, everyone is likely vulnerable, so we should expect that an extremely large number of people will be infected.
Is it so serious despite the alternative medicines we have in hand?
Yes, it is a really big deal. Because there are no real barriers to spread and the reproductive factor (R0) is so high, it is possible and indeed likely that 20% to 70% of the global population will be infected.
That is 1.5 billion to 5 billion people. With an estimated mortality rate of about 2%, that is 30 million to 100 million deaths globally.
In the United States, we might expect 66 million to 231 million people will be infected, with as many as 1.2 million to 4.6 million dead, possibly more. That may well also be an overestimate; we don’t know a “true” mortality rate yet, but the WHO estimates it may be as high as 3.4%.
But the mortality rate isn’t as important as the fact that the medical system will be overwhelmed, because this will all happen really fast. And yes, many people will die. We just don’t know how many yet.
But we can limit the total number of people infected if we take serious containment measures early on. That will save lives.
How quickly will it spread?
We don’t know, but the rate of doubling of known cases seems to be every few days — with the caveat that reported numbers are likely undercounting actual cases. This means that without major interventions, this infection will reach much of the world’s population in a matter of weeks or a few months. This could be as many as 1.5 billion to 5 billion people, as mentioned above.