Why getting tested quickly matters so much
30 April 2020
Opinion: Even after weeks of lockdown, people are still testing positive. Associate Professor Siouxsie Wiles explains why that is – and why getting tested swiftly if you have symptoms is really important.
For days now, the numbers of new confirmed and probable cases of Covid-19 in Aotearoa New Zealand have been in single figures. But they haven’t been zero. Lots of people have noticed and have started asking me why, after all the weeks we’ve spent in lockdown, we still have people testing positive for the virus.
It’s a good question and I can think of several reasons. But before I get into that, a quick reminder. Here in New Zealand we test for the genetic material of the virus. The test is very sensitive and reliable. It can detect very small amounts of the virus, and it can detect both viable infectious virus as well as bits of broken-down virus that are no longer infectious.
When someone has symptoms and tests positive for the virus, that likely means they picked up the virus at some point in the previous two weeks. But if someone no longer has symptoms, they can still test positive for the virus. This doesn’t necessarily mean they are still infectious.
So why do the cases keep coming?
People have still been flying back to New Zealand from overseas
While our borders are basically shut, in the last weeks we’ve continued to see people returning to New Zealand from overseas. For as long as the virus is infecting people in other countries there is the chance someone will arrive here with it. That’s why at the moment people coming from overseas are being put straight into managed isolation or, if they display symptoms, quarantine proper.
People are being tested who had the virus a few weeks ago
An interesting case was confirmed on the weekend in Taranaki. A woman returned from France in mid-March but didn’t test positive until late April. This has led some people to ask whether this means the incubation period was more than 14 days.
Dr Jonathan Jarman who is the medical officer of health for the Taranaki District Health Board has shed some light on this case. He is quoted as saying, “this is quite an unusual situation where the person with the infection has returned home in mid-March after travelling through Europe, and had mild symptoms a few days later.” He added that the person has “lived symptom-free until just this week when she decided to get tested for Covid-19 because she had a runny nose”.
This is quite an unusual situation where the person with the infection
has returned home in mid-March after travelling through Europe, and had
mild symptoms a few days later.
That suggests that the person involved had a mild case of Covid-19 related to their travel in France. They recovered from that but maybe came down with a cold which prompted them to get tested. That test was positive. There is plenty of data showing that people can still test positive for weeks after they have had Covid-19. As I explained earlier, the genetic test for the virus is very sensitive and can detect bits of broken-down virus. This is likely what has happened in this case.
People are catching the virus from someone in their bubble
Because we aren’t all self-isolating within our bubbles, some of the cases we’ve seen will be from links to known clusters that are spreading within bubbles. That’s why we were asked to keep our bubbles as small as possible. It means, the potential spread is substantially contained. It’s why we also might see more cases as people expand their bubbles in level three.
People are catching the virus from someone outside their bubble
It can be so easy for the virus to spread through our bubbles if people engage in a spot of bubble-breaking. I’ve seen lots of pictures of this from the first day of alert level three. Hopefully this bubble-breaking was just a one-off but if it becomes the norm then we are in trouble. Because the more people don’t stick to the rules of alert level three, the more likely we are to see cases rise. And because of the incubation period of the virus we may not see that for a week or two – just as the point we are all starting to get excited by the prospect of potentially going in to alert level two. Wouldn’t be absolutely heart-breaking to have to go back to level four instead?
Please get tested if you have any of the symptoms of Covid-19
As you know, we are now at alert level three. Keeping our bubbles small and making sure we keep up with physical distancing and hand washing are the main way we can make sure the virus doesn’t start spreading between people. You could also wear a cloth mask while out in public. But make sure you know how to wear it properly. Masks are about protecting others in case you have the virus.
Level three does mean though that some people are extending their bubbles and others are perhaps inadvertently having their bubbles broken. So one thing that’s really, really, really important to remember, is that if you have any symptoms at all that could be Covid-19, go and get tested. Please don’t delay. Even if you think it’s probably just a cold. Every day you wait to be sure your symptoms are really Covid-19 is valuable time lost by our contact tracers.
If you need reminding what the symptoms may be
Some new symptoms have been added recently so they now include a dry cough, fever, breathlessness, as well as a runny nose, sore throat, headache, body aches, sore muscles, fatigue, sneezing, chills, diarrhoea, and a loss of smell. Remember, don’t delay!
Associate Professor Siouxsie Wiles is a microbiologist from the Department of Molecular Medicine and Pathology in the Faculty of Medical and Health Sciences' School of Medical Sciences.
This article reflects the opinion of the author and not necessarily the views of the University of Auckland.
Used with permission from The Spinoff, Siouxsie Wiles & Toby Morris: Why getting tested quickly matters so much, 30 April 2020
Gilbert Wong | Research Communications Manager
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