Social Distancing Calculator - Coronavirus

Since coronavirus has become a major part of all of our lives, you should already be familiar with all the details about it. Nevertheless, let us recall some essential facts about coronavirus for the sake of clarity.

The novel coronavirus disease 2019 (COVID-19) is a respiratory disease that was first detected in China in December 2019 and became pandemic on 11th March 2020. Its most likely origin is as a bat disease, which was transmitted to another animal and then to a human, and the rest is history. The size of the infected population has grown exponentially, with a growth factor of about 1.

COVID-19 seems to be spreading quickly among humans. We still don't know exactly how it spreads, but the potential ways of transmission are by:

• respiratory droplets: coughing or sneezing,
• fomites: infected clothes, furniture, skin, door handle, etc. The virus may persist on surfaces for 9 days (or even for up to 27 days on some surfaces),
• airborne: the virus is mixed with air particles which can float, covering long distances.

COVID-19 symptoms may appear 2 to 14 days after initial infection. That's why people who believe that they have the disease should have some level of restricted movement for two weeks. The typical symptoms are initially flu-like and usually include:

• Fever;
• Dry cough;
• Shortness of breath after about a week (20% of patients require hospital treatment).

These symptoms can further develop into pneumonia (with chest tightness and chest pain). We rarely observe a runny nose, sneezing, or sore throat in a COVID-19 infection (only in 5% of cases). If you are exhibiting these symptoms, you likely have a cold. Symptoms in confirmed cases are usually mild (80% of cases), meaning that they can recover at home, while some are severe (13.8%), requiring hospitalization, critical (4.7%) requiring an intensive care unit (ICU), and even fatal (2%).

To make it easier to diagnose the illness, we summarized and compared the symptoms of COVID-19, flu, and cold in the picture below:

The pandemic of novel coronavirus remains a hot topic on both social and traditional media, and there can sometimes be two extreme camps:

1. Negligence: we don't need to worry much; COVID-19 is another flu with a mortality rate of only 2 percent
2. Panic: coronavirus outbreak is the biggest danger since the Spanish flu (which killed up to 100 million people), and may lead to the extinction of humanity;

Of course, both approaches don't reflect the real situation. Yes, COVID-19 is a new and dangerous flu that we can't neglect, but no, we won't all die.

The main problem with the coronavirus outbreak is that the reproduction number, R₀, (expected number of cases directly generated by one case) is large; recent studies on COVID-19 show that it could be between 1.4 and 3.8, or potentially even higher. Seasonal flu has an R₀ of 1.28. Therefore there is a risk that the number of sick people will snowball so quickly that healthcare services and infrastructure will run out of space for the newly infected.

Since the coronavirus incubation period can be between 2 & 14 days (5.1 days on average), infected people can spread the disease before they begin to show symptoms (some don't show any signs of infection for the entire duration of their infection). This fact, combined with a high reproduction number, makes it likely that the disease will spread to the whole world.

As of 3rd March, the WHO director-general stated that the mortality rate of COVID-19 is about 3.4% globally, compared to less than 1% for the seasonal flu. However, the fatality rate may change depending on the age group, sex, and pre-existing medical conditions of those infected. Among young, healthy women, some could be at risk due to early pregnancy, learn more about the first symptoms with the pregnancy test calculator and hCGlevels calculator. Remember that this mortality rate assumes that people receive proper medical assistance! Nobody knows how high it could be if hospitals become overwhelmed.

However, bear in mind that these mortality rates are calculated relative to confirmed cases of COVID-19. Nobody knows the total number of cases, because patients who have none or very mild symptoms may not be tested, and thus remain unidentified. In consequence, they are not taken into account when calculating the mortality rate.

So far, all strategies towards the containment of COVID-19 have only slowed the spreading of the virus. Meanwhile, many companies and academic institutions around the world are in constant pursuit of a vaccine to finally end the pandemic. They already have some promising candidates that are currently being tested on animals (and soon also on humans), but we probably won't get it until 2021, and even then, healthcare professionals will get it first.

So what can we do now? The Center for Disease Control and Prevention gives detailed instructions on How to Protect Yourself, and at the very beginning, we read that "The best way to prevent illness is to avoid being exposed to this virus". It sounds simple, but this is essential! A pandemic isn't the best time to travel or to meet friends outside. Instead, try to isolate yourself and stay at home any time it's possible.

Remember, you're responsible for not only your health but for that of the whole community. Living in isolation isn't easy (tens of millions of Chinese citizens have been in lockdown for over a month!), so prepare yourself by getting the books you always wanted to read or finally plan the project you've been procrastinating on for months. You could also start the new diet you always planned to (check our calorie deficit calculator and body fat calculator).

In their recent paper, Feasibility of controlling COVID-19 outbreaks by isolation of cases and contacts, scientists at the Centre for Mathematical Modelling of Infectious Diseases, at the London School of Hygiene & Tropical Medicine in the UK, found that the probability of controlling an outbreak drastically increases when we increase the amount of contact tracing and case isolation. As a result, we can reduce the effective reproduction number to less than one (R₀ < 1)!

It turns out that staying at home really does help! Use this social distancing calculator to explore their results and hopefully gain a better understanding of why staying at home is so important.

Picture from the Feasibility of controlling COVID-19 outbreaks by isolation of cases and contacts paper.

The social distancing calculator is a tool designed to improve public awareness about the importance of staying at home and isolating during the pandemic. It is based on the simulations made by scientists described in the paper we mentioned in the previous section. But how to use the social distancing calculator?

We simulate 1,000 outbreaks with seven parameters that are directly connected to the virus itself, the actions taken by the government, and your own decisions. You can specify these to your liking. We treat an outbreak as controlled if the number of cumulative cases is below 5,000, and there are no new infections 12 weeks after the initial cases. You can set:

• Initial cases - number of people in the newly detected outbreak. For COVID-19, the number of infected people at the Wuhan market was about 20.
• Reproduction number R₀ - the expected number of people directly infected by one case. For COVID-19, it's probably between 1.4 and 3.8.
• Asymptomatic cases - the probability that a person has been infected but won't have any symptoms at all. The virus can still be spread! For COVID-19, it's believed to be more than 10%.
• Transmission before symptoms - the percentage of infected people that can still spread the disease even though they don't have any symptoms yet due to the incubation period of a virus. For COVID-19, more that 10% of patients are infected by somebody who has the virus but does not yet have symptoms.
• Delay in isolation process - the time between symptom onset and isolation of the person by the government. You can choose between a short delay (2 - 5 days), estimated from the late stages of the 2003 SARS outbreak in Singapore, or a long delay (5 - 11 days), from the early phase of the COVID-19 outbreak in Wuhan.
• Careful with traced contacts? - if yes, then people that had contact with the infected person are isolated immediately after the infected person's symptoms manifested. If no, they might still infect other people due to the isolation delay.
• Isolation level - to what extent are you ready to isolate yourself from the community? Input value a between 0% - 100%, where 0% - you don't care about the pandemic at all and live as before; 100% - you're doing everything to prevent the spread of the virus by almost total isolation.

As a result, you can see four graphs in total (two in the simple mode and two in the advanced mode):

• Isolation impact on the number of people infected - shows how many people you would protect from infection and death (assuming the death rate of 3.4% for COVID-19) by just sitting at home;

• Isolation impact on the effective reproduction number R₀ - the effective reproduction number is an expected number of people directly infected by one person after making the decision to remain indoors. You can compare the obtained effective reproduction number after your self-isolation with the reproduction number of the seasonal flu.

• Outbreaks controlled vs. contact tracing level (advanced mode) - shows what percentage of simulated outbreaks have been controlled after tracing x% of contacts (in our calculator, we equate isolation level with contacts tracing - see the disclaimer below). The first point is the probability of outbreak control with no contact tracing, and the last point is with 100% contact tracing.

• Outbreaks controlled vs. reproduction number R₀ (advanced mode) - shows the same thing as the previous graph but as a function of reproduction number instead.

Try our social isolation calculator with different combinations of parameters (we simulated nearly 600 of them!) to see how self-isolation may increase the chances of stopping a disease.

WHO urged countries to hire additional thousands of contact tracers who can find and isolate anyone who may be infected. Let's work together and help our government end this pandemic. All you need to do is stay at home!

Disclaimer: Although in the original study, the authors performed the simulations as a function of the efficiency of COVID-19 contacts tracing, we decided to use isolation level instead. We believe that self-isolation might lead to similar or even better results.

There are many available sources of information about COVID-19 pandemic. Here we provide you with a few we like the most:

• Centers for Disease Control and Prevention - guidelines for protection and steps to follow when you're sick.
• Coronavirus COVID-19 Global Cases Map by CSSE at JHU - an interactive map for cumulative confirmed and active cases of the COVID-19
• NY Times Coronavirus Map - the World, United States, Asia, and Europe coronavirus tracking maps
• Coronavirus Cases by Worldometer - comprehensive and updated statistics about the COVID-19