COVID-19: Stopping the spread

How to reduce the spread of infection in your home

(Healthify NZ, in partnership with Northland DHB & Ministry of Health, 2022)

How to protect yourself and others from COVID-19
To protect yourself and others from COVID infection, it’s important to: stay home if you’re sick and get a test get vaccinated as soon as you can wear a face covering use basic hygiene: regularly wash and dry your hands cough or sneeze into a disposable tissue or into your elbow clean frequently touched surfaces practise physical distancing in public when possible

The virus that causes COVID-19 is mostly spread in particles that escape from an infected person’s mouth or nose when they breathe, speak, cough, sneeze or sing.

These particles range in size. Larger and heavier particles (droplets) quickly fall to the ground or other surfaces within seconds or minutes. Smaller particles (aerosols) can remain airborne for minutes to hours.

Infection occurs in 3 main ways:

breathing in air that contains infectious particles
infectious particles landing on your mouth, nose or eyes through being coughed or sneezed on
touching your mouth, nose or eyes when your hands have been contaminated by the virus (either through direct contamination, or indirectly by touching surfaces contaminated with the virus).

The virus that causes COVID-19 is a new virus, and our understanding of how it spreads has changed over time. Spread by aerosols appears to be more important than thought at first.

Current evidence suggests that catching COVID-19 from surfaces is the least common way of catching it, but it is still important to clean surfaces to reduce the risk. The length of time the virus can survive on surfaces depends on many factors including temperature, humidity and UV or sunlight.

You can catch germs (such as viruses and bacteria) when you touch contaminated objects or surfaces and then touch your face (mouth, eyes and nose). You can spread certain germs casually by touching another person. Washing your hands properly with soap and water can remove the germs from your hands and significantly reduce their spread.

When it comes to virus-busting, soap is great at getting rid of coronaviruses such as COVID-19. Washing your hands with soap kills the virus by bursting its protective bubble.

Chemical bonds allow bacteria, viruses and grime to stick to surfaces, including your hands. Soap molecules break these bonds and lift the bugs off your skin. That is because one end of a soap molecule bonds with water and the other with fat, and the virus has a lipid (type of fat) membrane.

When you rinse your hands, all the bugs that have been damaged, trapped and killed by soap molecules are washed away.

The key thing is to know how to do it so it works:

wash your hands often
use soap
take 20 seconds
dry your hands well.

If you don’t have access to soap and water, use hand sanitiser. Make sure it contains at least 60% alcohol and rub it into your hands for at least 20 seconds to ensure full coverage. Read more about handwashing.

COVID-19 is spread by droplets. If you don't cover your cough or sneeze, the large droplets spray out and may reach other people and surfaces. They are too large to stay in the air for long, so they quickly settle on surrounding things.

If you cough or sneeze into your hand, you can then spread those droplets onto anything you touch. If you cough or sneeze into your elbow, it keeps the virus off your hands, so you won’t spread it onto things you touch. Read more about how to cough and sneeze properly.

Use a tissue not a cloth handkerchief. Put any used tissues in a bin or a bag immediately. Then wash your hands thoroughly. Then dry them. This reduces your risk of the virus staying on your hands after you have blown your nose.

Trying to not touch your eyes, nose and mouth helps because your hands touch many surfaces and can pick up viruses, including COVID-19.

Once you have the infection on your hands, you can transfer the virus to your eyes, nose or mouth whenever you touch your face. From there, the virus can enter your body and make you sick.

Current evidence suggests that catching COVID-19 from surfaces is the least common, but it is still important to clean surfaces to reduce the risk. The length of time the virus can survive on surfaces depends on many factors including temperature, humidity and UV or sunlight.

Regularly clean frequently used surfaces, such as phones, keyboards, door handles, remote controls, benches, tables, bathroom fixtures and toilets.

Use a disinfectant that is antiviral and follow instructions. Look for one that contains hypochlorite (which is the main active ingredient in bleach) or activated hydrogen peroxide (0.5%). Others may contain benzalkonium chloride, though some studies have shown this is less effective against coronaviruses.

You could also just use conventional bleach (at 0.1–0.2% available chlorine – check the back of your bottle) in water. You can also use ethanol alcohol or isopropyl alcohol.

A person is most infectious and more likely to spread the virus in the few days around the time that symptoms develop. This means that some people can be contagious before they develop symptoms.

The risk of becoming infected increases the closer you are to a person and the longer you are close to that person, especially if this contact occurs in poorly ventilated indoor spaces.

Most large droplets will fall to the ground within 2 metres. However, in some situations the virus has been transmitted to people more than 2 metres away, or to people who passed through a space soon after the infectious person left.

Things that increase the risk of this ‘long-range’ infection include:

being in enclosed spaces with poor ventilation within which fine particles containing virus can build-up
being near an infected person breathing heavily (for example, due to exercise, singing or shouting)
being exposed to these conditions for a longer period of time.

The ‘3 Cs’ are situations where spread of the virus is most likely are:

closed spaces with poor ventilation
crowded places with many people nearby
close-contact settings, especially where people have close-range conversations, singing or shouting.

The risk is highest when these factors overlap, eg, in small, poorly ventilated spaces with lots of people talking loudly or shouting. The risk is lower outside, with fewer people, if they are widely spread.

A face mask helps stop infectious droplets spreading when someone speaks, laughs, coughs or sneezes. This includes someone who has COVID-19 but feels well or has no obvious symptoms.

To prevent community spread, it is best to use a medical-grade disposable face mask as long as it fits well and is worn correctly. Recent research has found that these can be washed and worn more than once.

See this animation of how to stop the spread of COVID-19:

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(Source: The Spinoff, NZ, 2020)