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Doctors and vets answer your questions on Covid-19, living in a bubble and sanitisation

Some of us live with essential workers, pets or the vulnerable. How vigilant do we need to be with cleaning surfaces? What are the guidelines around physical contact within our bubble?

By One Health Aoteaora
As New Zealanders settle into lockdown we are discovering that with each passing day we have new questions around self-isolation, sanitisation and staying safe.
Some of us are living with essential workers. Some of us are in a bubble with a senior citizen or infant. Some of us have pets. Some of us are in shared custody arrangements with a child going between two homes. How vigilant do we need to be with cleaning surfaces and physical distancing to keep ourselves and our loved ones safe?
Here, One Health Aotearoa members answer your questions.
One Health Aotearoa is a collection of experts in human, animal or environmental health who work together to provide new approaches to the management, prevention and control of infectious diseases.

Now I am in my bubble how obsessive do we need to be with cleaning surfaces and items such as door handles?

The point about isolating ourselves in our bubbles is that we know there is community transmission but we don't know who is infected but not yet showing symptoms. So, by shutting ourselves away with a small number of other people we ensure that if any of us are infected, there is a limited number of people we can infect in our turn. But it would be preferable if we actually don't infect the other people in our bubble.
So, just in case someone in your bubble has been infected but doesn't know it yet, we suggest cleaning things that everyone touches, like door handles and taps, at least once a day.
It is important to be rigorous about cleaning hands on returning to the house after being out for any reason.
If anyone in the bubble gets symptoms, isolate them in a room and clean everything they touch (door handles, bathroom taps) after they've touched it. It is, of course, a good idea to practice good personal hygiene to minimise the chances of any other viruses being shared around your bubble companions.

I live with an essential worker. What special precautions should we be taking when they come home? Should they shower, or use separate bedrooms?

There are several things in place already to stop the spread of infection. Essential workers should have measures in place at work to minimise the risk of contracting Covid-19. There is detailed information on the Ministry of Health website about this, but some examples include staggered meal breaks, flexible leave arrangements, physical distancing of staff, arranging shifts to reduce numbers on site at any one time, and ensuring access to ways of maintaining hand hygiene practices, and protective equipment.
It is important both management and other staff work as a team to make sure this happens. Essential workers should maintain physical distancing while travelling to and from work, or doing essential jobs such as shopping. Do not get tempted to ignore advice about this.
Essential workers have a responsibility to use hand hygiene before leaving work and before coming into the house. They could, for example, have an easily-accessible personal hand sanitiser in their car. Doing these things places a large barrier between the work place and the home bubble.
Some people may wish to take some further steps as extra safety measures. These might include showering and putting on fresh clothes as soon as the worker gets home. In most circumstances this should be effective and people can live as normally as possible and enjoy each other's company.

I don't understand why Covid-19 is more dangerous than the flu, which kills lots of people every year and mutates every season. How is Covid-19 different, and why are we making a bigger fuss about it?

Although many comparisons have been made between Covid-19 and the flu, it is important to appreciate they are different diseases caused by quite different viruses. Yes, some of the symptoms, such as cough and fever, are similar.
However, there are several important differences. Covid-19 is different from flu because there's no vaccine yet and no-one has had this infection before, so no-one in the population has any immunity and it could spread very widely.
The proportion of people who die or get serious illness from this virus is higher than the flu. So, with more people getting infected and a greater proportion with serious illness, there is a very real potential to overwhelm our health care system's ability to look after all the people with serious illness.
In this situation, people would die not only from Covid-19 but potentially from other conditions because the health service might not be able to provide treatment for them.

Why does the virus last different times on different surfaces? Which are most dangerous surfaces or objects?

Coronaviruses, such as the virus responsible for Covid-19, belong to a group of viruses that are surrounded by a lipid envelope. This envelope makes them more vulnerable to drying, heat, ultra violet light, detergents, disinfectants and sanitisers, when compared to viruses that don't have such an envelope, such as norovirus. Enveloped viruses tend to survive up to a few days in the environment, compared to non-enveloped viruses that can survive for weeks.

The rise of coronavirus in New Zealand

A recent study found the virus causing Covid-19 survives better on plastic and stainless steel than on copper and cardboard. In an experiment using aerosols that mimic those produced in the human respiratory tract, the virus survived for at least three days on plastic and stainless steel, whereas on copper and cardboard it was not detectable after four and 24 hours respectively.
Copper and copper alloys are known to have strong antimicrobial properties, which would explain the short survival on this material.
The surfaces and objects that are likely to be most important for transmission of the virus are those that are made of materials that support longer survival and have more contact with people's hands and nasal, cough and sneeze secretions. Examples would be toys and door handles; they are handled/touched frequently, and are likely to be made of material that allows longer virus survival.

Is there a chance Covid-19 could mutate to become more or less dangerous?

Yes, there is a chance. All viruses change small parts of their genetic code by mutating over time – it's a natural process. But it's not showing signs of mutating quickly at the moment and seems to be relatively stable compared to other viruses such as flu viruses. And there's no particular reason to expect that if it mutates it will become more dangerous.
Mutations in the virus are being tracked continuously in multiple countries around the world, including New Zealand, as the pandemic progresses. This global effort is being used to understand the movement of the virus between countries and how it is evolving following community transmission.
Scientists are carefully looking for potential changes that could affect how the virus behaves, such as whether it is picking up ways to avoid our immune system. There is no evidence of that to date, which is good news for the development of treatments and vaccines.

I've heard dogs have caught Covid-19. How do viruses spread between animals and humans? And should I be worried about my pet?

There is no evidence to suggest pets are important for spreading Covid-19 to people. Although there are reports of two dogs and one cat testing positive for the virus, this was most likely due to the animals being contaminated by their owners, and the dogs did not show signs of illness.
Animals do have other coronaviruses. For example there are vaccinations against coronaviruses that cause illness in cats and cattle, but these are different to the virus that causes Covid-19 and they do not cause disease in people. There are other viruses that spread directly from animals to people, such as avian influenza or 'bird flu', and the viruses that cause Covid-19 and SARS did initially cross over from wild animals to people, but since then spread has been human-to-human.
The coat of your animal is like any other surface and could become contaminated by hands and nasal, cough and sneeze secretions. So to minimise any risk, treat your pet as part of the same household 'bubble' and practice physical distancing as much as is practical, particularly with pets from other households.
Practice good hand hygiene, and avoid very close contact with your pets, such as kissing them, sharing food or allowing them to lick your face.

We are in lock-down for at least a month, but what's to stop the virus taking off again as soon as we come out of isolation?

The hope is all the people who are currently infected without knowing it will have their illness without infecting more people (other than, potentially, some of the members of their bubble). By the end of the period of Alert Level 4, all those 'chains of transmission' should have burned themselves out, and in principle when we come out of Alert Level 4 there could be no further infected people out in the community.
However, it's always possible that there will still be a few infected people, and once we re-open our borders it will also be impossible to completely eliminate people coming from overseas bringing the virus in with them. This could set up new waves of infection, particularly if a high proportion of the population has not been infected and become immune. This happened in New Zealand during the 1918 flu pandemic.
However, the period of lockdown should give us time to increase our capacity to test, contact trace, and isolate contacts of any new cases, so that we can keep the numbers of cases under control.
This Q&A was produced by One Health Aoteaora members. One Health Aotearoa is a collection of experts in human, animal or environmental health who work together to provide new approaches to the management, prevention and control of infectious diseases.