The symptoms of COVID-19, the disease caused by Coronavirus, can be tricky to distinguish from the flu’s for days. Also given the ways it spreads, it’s natural for us to assume it to be something like the flu that just pops out of the blue, and then suddenly disappears.

But COVID-19 is threateningly different from the flu. Owing to their similarities in terms of symptoms and transmission, I am going to compare these two contagions and point out the disparities between them and show what makes COVID-19 much more dangerous.

Let’s start with how infectiousness of a disease and odds of an outbreak are measured.

Measles is a highly contagious respiratory illness caused by a virus. Just one infected person is likely to pass the disease to 12 to 18 others. This estimate is called a disease’s Basic Reproduction Number, or R-naught (R0).

In more technical terms, R-naught is an epidemiologic metric used to indicate the intensity of an outbreak that an infectious disease has. So if a person is sick and goes on to infect a population that has no immunity to the virus, the number of individuals that that person, on average, would infect can be estimated using the R-naught number.

Zika is less contagious as compared to measles; it has an R-naught of 6.6. For Diphtheria, it’s about 6 to 7.  For the seasonal flu, it’s little over one. And for COVID-19, it’s about two.

When you compare the basic reproduction factor of the flu and COVID-19, the difference doesn’t seem that big; especially when you stack them up against those highly contagious diseases.

Moreover, they appear to have similar disease presentation: both can lead to fever, cough and even respiratory disease like pneumonia, which can result in death. They even share the same mode of transmission, that is – through contacts, droplets and fomites. So thinking COVID-19 is like the flu is quite natural.

Now, let’s take a closer look at R-naught numbers of the flu and COVID-19 again.

The flu has an R-naught of 1.3, which means one sick person gets to pass on the disease to either one or two other people. Then in the next cycle, these people can get to infect other three, then these three to other four and if these cycles continue for the tenth time, the number of infected people could well be over 60.

Below is an illustration of how an infected person will go on to infect other in an imagine scenario where the disease has an R-naught of 1.3.

r naught = 1.3

Now let’s direct our model to COVID-19.

COVID-19 been estimated to have an R-naught of somewhere between 2 to 2.5. This means that if one person gets to infect two other people, and these two people infect four other, then by the time it reaches the 7th cycle (as illustrated in the image below), more than 250 people would be infected, and the number multiplies by a factor of 2 with each successive cycle.

Can you figure how many cases there would be after ten cycles? That’s right, that’s more than 2000 cases.

The difference is stupendous! That’s because COVID-19 is on a whole different league.

Death Rate

Another thing to consider is the mortality rate. The mortality rate of seasonal flu is 0.1 percent, and for COVID-19, it is estimated to be ten times as that.

For comparison, the seasonal flu claims as many as 600,000 lives every year. As of April, COVID-19 has already claimed over 200,000 lives globally, and these numbers are expected to go way up by the end of the year.

Look at it; we have had this only for a few months and have not even grasped the full picture of its symptoms and severity. We can smell trouble brewing already, and if we don’t act responsibly, we are in for an ordeal of unprecedented muss upheaval.

Incubation Period

Another big difference between COVID-19 and the flu is the incubation period, that is – how long it takes for the symptoms to appear after contracting the virus.

The flu tends to have faster onset of symptoms (2 days at average) and be more severe, so there are far fewer mild and asymptomatic people walking around spreading the disease.

However, COVID-19 has a much slower symptoms onset. Although it usually takes five days before you start to feel sick after being infected, it can sometimes takes two weeks (12 to 14 days). During most of this period, you could be contagious.

 No Natural Immunity

COVID-19 is a brand new virus that we haven’t seen before. We have no immunity to it. And with no vaccine to prevent it, nearly everyone is susceptible.

As of now, nearly 30 percent of people who have tested positive for COVID-90 have been hospitalized, but these numbers are expected to grow in coming months.

For the flu, only 2 percent of the infected people end up in the hospital. Because there’s already a number of people in the population who either have had their flu shot, or have already carried the strain.

Health experts recommend getting a flu shot every year. The idea is that if enough of us with immunity are introduced in a given population, we can keep the virus from reaching those without. This means that the more immunized people we have, the more we can protect those that are susceptible to the virus.

As indicated above, the flu has a fatality rate of 0.1 percent. For COVID-19, it is estimated to be somewhere between 1 and 3 percent. However, for older individuals, or those with preexisting conditions, it is way higher.

Remember that the COVID-19, like the flu, is highly contagious, but what makes it much more dangerous is its slower onset of symptoms. So by the time you’re infectious, you wouldn’t be bedridden; you would feel well enough to go to a mall, a theater, an airport – and be a potential spreader. Also, with no cure and no vaccines currently available, it’s thousand times worse than the flu. Experts have warned that the epidemic could spread to about 60 percent of the world’s population.

How we, as responsible citizens, can take part in controlling the pandemic.

One of the few defenses we have against COVID-19 is limiting our social interactions.  We can break the chain of transmission with aggressive social distancing. That is – by not being around anyone and staying home as much as possible. Let the government and experts handle the rest.

We can all agree that the coronavirus pandemic, which started in the city of Wuhan, China, has taken the world by surprise. It has crumbled economies and thrown millions out of work. The number of deaths attributed to it is increasing exponentially, and with this crisis comes a new, uncertain threat to humanity.

But there’s hope. There are people out there fighting this invisible enemy at the front lines. Humanity has endured crises such as this before, and this too shall pass.

 Stay Home. Save Lives.

I am the original author of this article, and it first appeared on print as well as web edition of Imphal Free Press. Content has been slightly modified for relevancy.