4th April, 20207 min read

Why and how should we test for the coronavirus?

Why and how should we test for the coronavirus?
Medically reviewed

Public health experts have made it clear that testing people for coronavirus is vital if the pandemic is to be brought under control.

By testing everyone who thinks they may have COVID-19, the illness caused by the coronavirus, authorities will know exactly who is and isn’t infected - and have a better picture of where the virus is spreading.

If someone tests positive for COVID-19, they can self-isolate and the people they’ve been in contact with can be traced and tested, and can self-isolate as well.

The more you do this, the more you stop the virus from spreading - the World Health Organization (WHO) has stressed this since the beginning of the pandemic.

But testing everyone isn’t as easy as it may sound.

How useful is testing in controlling the virus?

Testing, tracing and isolating people is the basis of any outbreak response - and a few countries have proved that it works for the coronavirus.

South Korea was one of the first countries outside China to be affected by the coronavirus back in February. It saw thousands of cases in only a few weeks. But the government quickly rolled out testing and contact tracing, and put people under quarantine, which quickly helped to reduce the number of new cases.

More than 620,000 tests have been done to date and more than 1,400 people have been put in quarantine. South Korea is now reporting under 5 new cases each day - and even fewer deaths - while other countries continue to report thousands of new cases.

Hong Kong took a similar approach, testing everyone who had symptoms, but also asking anyone who had been in contact with someone who tested positive to quarantine for 14 days - the maximum amount of time it usually takes to develop symptoms. Authorities even set up special camps to send people to.

To date, Hong Kong has reported a little over 1,000 cases.

Germany has been testing hundreds of thousands of people each week, resulting in the number of new cases reported falling since early April.

But the success seen in these countries comes down to their overall approach.

A recent report by Imperial College London found that tracing contacts and putting people with symptoms in quarantine were more effective at controlling the spread of the coronavirus than testing alone. Other studies have found the same.

Many countries that didn’t test for coronavirus early in the pandemic are now under pressure. That’s why a range of new tests are being developed to help meet the demand.

If they become available, many experts believe they will be key to controlling the outbreak and letting people out of lockdown - especially until a treatment or vaccine becomes available.

Swab test for coronavirus

How do the main tests work?

The main test being used worldwide is one that looks for the genetic part of the virus, called RNA.

The test involves using a long cotton bud to take a sample (swab) of fluids from your nose or throat, as these are areas the virus infects. The samples are then sent to a lab to check for the virus’ genetic material. If it’s present, you’re said to have tested positive -- though accuracy depends on whether swabs were taken properly.

It takes just a few hours to check a sample for the virus’ genes, but it can take a few days for your sample to reach the lab and for your results to come back.

The availability of tests is also limited as each test needs lots of parts and chemicals and needs skilled lab staff.

Antibody test

What other tests are available?

Another way to test for coronavirus is to look for antibodies in a person’s blood.

When a virus or any other bug infects you, your immune system develops antibodies to fight the infection. These antibodies stay in your blood, meaning you can look for them in blood samples and know if someone has been infected.

This is a simpler test than looking for coronavirus genes, and it can be done on a larger scale. You only need a drop of blood to search for antibodies, so antibody tests can be carried out by trained healthcare staff or potentially done at home using a portable test.

Home tests already exist, but they aren’t all accurate.

Public Health England (PHE) has advised against using these tests in the community at the moment, but many companies are working to make them more effective and it’s hoped the tests will eventually become available for anyone to use.

In the meantime, PHE has begun large studies in the UK testing people using both throat and nose swabs, and blood samples to track how the virus is spreading.

The Centers for Disease Control and Prevention (CDC) in the US started using antibody blood tests at the end of March to get a better idea of who has been infected in the wider population.

Immunity passports for COVID-19

Immunity passports

A key goal behind using antibody tests is to potentially identify who has already been infected. Doing so could help people to safely start returning to work -- an idea known as an ‘immunity passport’. This would help authorities slowly end lockdowns.

But the WHO says this isn’t a good idea until we know more about the virus, how it infects people how our immune system reacts to it, and if you can get COVID-19 more than once.

For now, countries are looking into it as they explore how we can come out of lockdown and slowly return to regular life.


If you think you may have coronavirus, you can use our COVID-19 Symptom Mapper to check your symptoms and compare them with others around the world.

This should give you a better understanding of how the illness is affecting you and will help us to map the spread of the outbreak.


References:

WHO Director-General's opening remarks at the media briefing on COVID-19 - 16 March 2020 [Internet]. Who.int. 2020 [cited 7 April 2020]. Available here.

Ministry of Health and Welfare C. Coronavirus disease 19(COVID-19) [Internet]. Coronavirus disease 19(COVID-19). 2020 [cited 1 May 2020]. Available here.

Who.int. 2020 [cited 1 May 2020]. Available here.

Rki.de. 2020 [cited 1 May 2020]. Available here.

RKI - Coronavirus SARS-CoV-2 - Situation report - 27 Apr 2020 [Internet]. Rki.de. 2020 [cited 1 May 2020]. Available here.

Cowling B, Ali S, Ng T, Tsang T, Li J, Fong M et al. Impact assessment of non-pharmaceutical interventions against coronavirus disease 2019 and influenza in Hong Kong: an observational study. 2020.

COVID-19 Thematic Website, Together, We Fight the Virus, Home [Internet]. Coronavirus.gov.hk. 2020 [cited 1 May 2020]. Available here.

Briefing: Coronavirus (COVID-19) testing [Internet]. Abpi.org.uk. 2020 [cited 1 May 2020]. Available here.

Guidance on coronavirus (COVID-19) tests and testing kits [Internet]. GOV.UK. 2020 [cited 1 May 2020]. Available here.

Coronavirus Disease 2019 (COVID-19) [Internet]. Centers for Disease Control and Prevention. 2020 [cited 1 May 2020]. Available here.

Government begins large-scale virus infection and antibody test study [Internet]. GOV.UK. 2020 [cited 1 May 2020]. Available here.

"Immunity passports" in the context of COVID-19 [Internet]. Who.int. 2020 [cited 1 May 2020]. Available here.

Who.int. 2020 [cited 1 May 2020]. Available here.

Updates C, London I, Campus S. Report 16 - Role of testing in COVID-19 control [Internet]. Imperial College London. 2020 [cited 1 May 2020]. Available here.

Ministry of Health and Welfare C. Coronavirus disease 19(COVID-19) [Internet]. Coronavirus disease 19(COVID-19). 2020 [cited 1 May 2020]. Available here.

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