By Ramesh Shankar, Associate Professor, University of Connecticut.

How can Covid-19 spread?

The Coronavirus (formally, SARS-Cov-2 virus) which causes Covid-19 illness, spreads very easily from person to person. Each infected person typically infects between 2 and 3 other people, according to various scientific studies published so far. This rate of contagion is extremely high and dangerous. About 3 in 100 people who get the illness may die. About 10 to 15 of 100 people who get the illness may require hospitalization for pneumonia. It is of the utmost importance to practice social distancing to slow its spread, and to protect ourselves.

Respiratory droplets: coughs, sneezes

The virus spreads through cough or sneeze droplets from infected people. If you are at a wedding or social gathering, and someone sneezes or coughs, they are releasing millions of small droplets into the air. You are likely to inhale some of those droplets and catch Covid-19.

Remedy: always cover your cough or sneeze with your elbow. To prevent droplets from entering your nose, wear an N-95 mask when you are with people. If you have a cold or cough, please don’t step out, and always wear a mask - a simple surgical mask will be enough. If you don’t get a surgical mask, you can make a simple mask with a handkerchief and thread or wire.

Human contact

The virus spreads through handshakes, hugs and other human-to-human contact. If your friend is infected and they shake hands with you, you too will be infected.

Remedy: Frequently apply hand-sanitizer to your hands, or wash your hands with soap for 3 minutes. If you shook hands with someone, if you touched public surfaces such as toilet doors, restaurant doors, chairs in malls and other public places, or handles in buses or trains, be very aware that your hands could be having the Coronavirus. Do not touch your face, and at the earliest opportunity, wash your hands with soap for 3 minutes or apply hand-sanitizer.

Ask everyone in your house to frequently wash their hands with soap, including domestic help, cooks, drivers, and others who are in close proximity to your family.

Commonly touched surfaces

The virus lives on surfaces for a relatively long period: door handles, mobile phones, restaurant tables and chairs, kitchen surfaces, cardboard boxes used for e-commerce or food deliveries. It stays alive on plastic and stainless steel for upto 72 hours, on cardboard for upto 24 hours, and on copper for upto 4 hours.

Remedy: Wear gloves and clean frequently used surfaces with either (a) diluted bleach (one-and-a-half table spoons per liter of water), or (b) alcohol based cleaners with at least 70% alcohol, or (c) hydrogen peroxide based cleaning agents. Use a paper towel or cloth towel to rub the surfaces with the cleaning liquid. Let the surfaces become wet, and let it dry off - don’t wipe it with water.

The following is a list of products that are “expected to be effective against Covid-19” by the US Environmental Protection Agency:

https://www.epa.gov/pesticide-registration/list-n-disinfectants-use-against-sars-cov-2 }

Asymptomatic spread

To add to this complication, your friend could be infected for upto 5 to 10 days, and not show any symptoms (no cold, no cough, no fever) - and still infect you if you shake their hand or touch a door handle they touched. They could be standing close to you and talking, and one or two drops of their saliva may fall on your nose or mouth, and you can get infected. If you attend a wedding reception, and no one sneezes or coughs, are you going to be OK? Probably not, because someone in that wedding crowd may have Covid-19, and they may touch a chair, and you may touch that chair, and then scratch your nose. That is sufficient to infect you.

Remedy: Practice social distancing.

You have to assume that everyone may be infected, and you will not know who is or who is not infected, and they can infect you. So, avoid crowded places - restaurants, trains, buses, even grocery stores that are crowded. Avoid gyms, bars, and public parks. If possible, work from home. Stay at home, and go out only to buy groceries or essentials. If you do go out, wear a face mask and if possible wear gloves. Do not touch your face when you are outdoors.

Social distancing is extremely important in slowing the spread of Covid-19

Fig.1

Fig.1: If people go about as usual without social distancing, that causes a high rate of infection, overwhelming hospitals and leading to many deaths.

Fig.2

Fig.2: If people can practice high level of social distancing, that slows the rate of infection, so that hospital capacity is not overwhelmed, everyone can get treated and eventually we will develop “herd immunity” – most people in the population will eventually develop resistance to this disease. (Source: Based on a 2007 paper by CDC, the above illustration is by New Zealand microbiologist Siouxsie Wiles and drawn by illustrator Toby Morris.)

Flattening the curve

In practicing social distancing, we are trying to “flatten the curve” of the spread of the illness. If everyone goes about as usual (fig.1(a)), too many people will get infected in a short period of time - maybe in a month or two months from now, and that will flood our hospitals. People with pneumonia or other complications from Covid-19 will need to be put on ventilators for one or two weeks (or longer) to survive.

On the other hand, if we practice strict social distancing, we can slow down the rate at which the disease infects people (fig.1(b)): people will get infected at a slower rate (over several months), and that will give our hospitals a chance to heal everyone. Over time, the population as a whole will develop immunity to this disease, and we can prevent many deaths and suffering.

In conclusion

Stay at home. Avoid crowds, avoid buses and trains, markets, restaurants, hotels, and other public places. Clean frequently touched surfaces often. Do not touch your face. Frequently wash your hands.