Coronavirus Q&A: HSE expert answers your questions
‘We expect most people who are contacts do not have infection,’ says microbiologist
Prof Martin Cormican, microbiologist and disease expert at NUI Galway and the HSE, at a media briefing on Covid-19 at the HSE in Dublin. Photograph: Gareth Chaney/Collins
If someone in my household is a contact and is advised to stay at home, how is it safe for the rest of the family to go about as normal?
The person who is a contact may have become infected with the virus. If they are infected with the virus, it has to grow in them for at least some days before it can pass on to you or anyone else in the house.
Experience so far shows that the virus does not generally spread from a person who has the infection until the person starts to have some symptoms. So we expect most people who are contacts do not have infection. We also expect any contact who turns out to have infection is most unlikely to spread the virus to you before they get sick. If they do spread the virus to you, you can’t pass it on until it has grown in you for at least some days.
Therefore, the risk that you could spread infection is so low that it is reasonable to live your life as normal.
Why don’t you just test everybody?
The test for the virus involves swabbing the throat and nose. The lab checks for virus genes on the swab. If there are enough virus genes, the test gives a signal (virus detected). If there are not enough virus genes, the test gives no signal (virus not detected).
So no signal means there are no virus genes, or there aren’t enough to give a signal. “Virus not detected” is not proof there is no virus.
The test works well for finding the virus in a person who has symptoms and who is shedding a lot of virus. If someone gets infected, the virus has to grow in them for some days before the test can detect it. We know the test works well by the time the person gets sick (because there is enough virus).
We do not know enough about how well it works before the person gets sick. Testing contacts too early – before they get sick – can give false reassurance.
Neither is it the best use of the testing capacity that we have at the National Virus Reference Laboratory.
What if someone in the house with a contact is already sick with something else?
The steps to reduce the risk of infection are the same for a person who is already sick. If a person with lung or heart disease or a problem with their immune system catches the virus, the infection may be more severe. There is no drug or vaccine that offers additional protection. If it is practical, they could decide to live elsewhere for the 14 days. Public health do not recommend this as necessary but some people do decide to do this if they can.
Can contacts in isolation go outside ?
Yes. They can go out for a run or a walk outside if they avoid contact with other people. Two people who are contacts in the same household could walk or kick a ball about together, outside in a place away from other people.
The important point is to do everything possible to keep contacts 1 metre or more away from anyone who is not in the household and to keep them away from places where virus in their cough or sneeze might settle on something that anyone else will touch soon afterwards.
Is there a risk for me if I live in a house with someone who is a contact?
Yes, a person living with a contact will become a contact if that person becomes ill, so there is some risk in being in the same house as a contact.
The risk can be greatly reduced by keeping distance as much as possible and by ensuring proper hand hygiene as much as possible.
Keeping things clean is very important, particularly if the contact is a partner or child.
This risk is something you may accept so you can support those you care about. You may not have much choice if you have no other place to live.
How can we stop respiratory viruses spreading?
Minimise unnecessary contact. Keep your hands to yourself and learn how to clean hands properly.
Protect your mucous membranes. Keep your hands away from face, eyes, nose and mouth. Respiratory viruses like influenza and coronavirus have to get on to mucous membranes; they can’t get through skin.
Keep your distance from sneezes and coughs (more than 1 metre where possible).
Use respiratory hygiene and cough etiquette. Use tissues and bin them afterwards, or use the crook of the elbow.