Covid Testing; Everything you need to know

Thursday 25th Mar 2021 |

When travel is reopened, what part will testing play? 

Currently, most countries say they will require holidaymakers to have a negative COVID-19 test no more than 72 hours before they travel. Most countries say this must be a PCR test, which can detect COVID-19 at an earlier stage as it is more sensitive than other tests, allowing greater confidence.

Will holidaymakers who have been vaccinated need to take a COVID-19 test?

The WHO has indicated that vaccines do not rule out current COVID-19 safety measures, such as mask wearing and testing. We don’t yet know whether vaccines stop people getting or transmitting COVID-19, so PCR testing is the most effective way of ensuring a holidaymaker is not carrying COVID-19 when they travel. 

Will I need a vaccine passport?

When it comes to travel, the concept of ‘vaccine passports’ has become a hot topic. Desperate for a return to normality, many countries are contemplating endorsing ‘vaccine passports’ as part of their plans to reignite international travel over the coming months. Many are unhappy with the idea of ‘vaccine passports’ however, due to their concern that vaccine passports could lead to discrimination against those who have not been vaccinated for cultural or medical reasons, or because they are not on the government’s priority list. In response to this unrest, the EU is expected to draw up plans for ‘Green Digital Certificates’, which would show whether EU citizens have had the vaccine, a negative COVID-19 test, or have previously had COVID-19. This Vaccine certificate is consistent with the WHO’s recommendations.  

Does the EU’s Digital Green Certificate remove the need for testing?

No. According to the EU’s launch announcement the certificate will be given to any EU citizen who can provide evidence that they have been vaccinated, have recently tested negative or have acquired antibodies after recovering from the virus. Around 24m people in Britain won’t receive their second vaccination until late summer and autumn, including many of those aged between 18 to 40 who are in the lowest risk groups, so testing is essential for them to travel abroad this summer. In addition, the WHO has made it clear that being vaccinated in itself does not fully mitigate the risk and COVID-19 safety measures will have to be retained. 

What are the different types of COVID-19 tests?

Broadly, there are two different types of testing. One to find out if a person currently has COVID-19 and the other determines whether they have previously had the virus, been vaccinated and built-up immunity (antibodies).

PCR 

PCR (Polymerise Chain Reaction) is currently the most common form of testing in the UK and at 99% accuracy, is seen as the most reliable test for viral carriage. If you have been tested by the NHS in a testing centre, or have been sent an NHS test in the post, this will have been a PCR test. A swab is used to collect a sample from the patient’s tonsils and inside their nose and this is then sent to a laboratory to test for genetic material called RNA. Bioscientists can then see whether the SARS-CoV-2 virus (the virus that causes COVID-19) is present.  

Lateral Flow

A rapid antigen test, also known as a lateral flow test, detects proteins on the surface of the virus, called antigens. Inserted into the nose or throat, the swab is then inserted into a tube of liquid. The liquid is then dropped onto a small strip, which will show two lines if it is positive, one line on the top if it is negative or one line on the bottom if the test is invalid. Lateral flow tests use similar technology to a pregnancy test. These tests are the cheapest option and return results within 30 minutes, but are less accurate than PCR tests, as they can only detect a high load of the COVID-19 virus so they can miss up to one third of positive cases. In addition, because of the low prevalence of COVID-19 in the population at present, they are also likely to have a high level of false positives. Antigen tests are therefore most accurate when used within a few days of the start of your symptoms, when there is a higher viral load present in your body. SAGE, the government’s scientific advisory group, has warned that with mass testing using lateral flow tests, false positives and false negatives could have ‘critical implications’ for effectiveness, so follow-up confirmatory tests are extremely important with lateral flow positive results. Given SAGE’s advice, lateral flow can only be considered a red light rather than a green light indication, meaning that facemasks, social distancing and viral hygiene will still be necessary. 

LAMP 

A similar process to PCR testing, LAMP (loop-mediated isothermal amplification) tests are the least common. They require a swab from the nose and throat and give results within 90 minutes. Similarly to lateral flow tests, LAMP tests can only detect a high load of COVID-19 virus, so they can miss people in the early stages of infection. Samples can be processed on-site and are analysed to confirm the presence or not of SARS-CoV-2 RNA.

Antibody 

Antibody testing looks at whether your body has produced any antibodies to fight against the virus. This is done via a blood test and must be taken from a COVID-19 patient whose symptoms ended three to four weeks before. This test then determines whether any antibodies are present. Currently, there are tests in development which would allow a person to submit their own blood test from home. 

Which test will holidaymakers need to travel?

For a definitive list of testing requirements, travellers should visit the official Gov.uk website (https://www.gov.uk/foreign-travel-advice/). It is important that holidaymakers check the rules for the destination they are visiting as it will be their responsibility to take the right tests. 

What about returning to the UK?

The UK has a testing process that is even more rigorous than the departures process as it requires arrivals to isolate for 10 days and have negative PCR tests on or before day 2, and on day 8 of their entry into the UK. 

Why are testing rules different by destination?

These are political decisions based on countries own experiences of COVID-19, the need to get their tourism industry up and running, and the safety procedures they already have in place. 

How much do tests cost?

PCR tests cost from around £80 per person for departures from most airports in the UK, with tests from Cignpost ExpressTest from £60 at Gatwick. 

The two-test procedure for arrivals into the UK currently costs from £190, as there is a different requirement for analysing the results. 

The current testing regime, as set out by the UK Government, is overly onerous and will require multiple tests for any families wishing to take a holiday. 

Are the testing rules likely to change?

We hope that the UK will simplify its own testing procedures for returning holidaymakers, to reduce both the cost and the inconvenience. The travel industry desperately needs this support, especially as concerns over new variants require the most accurate testing technology.

PCR testing is the only way to ensure the safety of people travelling, so it seems likely that testing will remain in place for some time yet.

How can tests be used to open up travel?

A combination of testing and vaccinations will provide the pathway out of the current crisis. The use of lateral flow tests have become more commonplace in recent months and there are some clear benefits to these tests. Results can usually be read within 30 minutes and they are a much faster indicator of infection than PCR tests, meaning positive cases can isolate immediately, breaking chains of transmission. However, they are also less accurate than PCR tests, which can detect COVID-19 even if only present in the smallest of traces.

Challenges on testing going forward

One of the biggest hurdles to the reopening of society will be one of confidence, as both consumers and the government must have complete faith in the accuracy of the tests taken to open up all sectors of society safely. Lateral flow tests are fast acting and cheap, but also miss a significant proportion of positive cases. In comparison, gold standard PCR tests, whilst costlier, produce significantly more accurate results. This has initiated a debate around how the government finds a balance between protecting lives and the cost effectiveness of their testing strategy, one which I suspect will continue to rage on until the end of the pandemic. 

Is a combined approach the solution? 

It’s clear COVID-19 testing is going to become a normal part of life, at the very least until the UK’s vaccination programme is complete. There are advantages and disadvantages to every type of test, so now, the challenge is to determine the most effective combination of testing. In my view, as long as people understand the limitations of lateral flow testing, using a combination of the different technologies available to us is the best solution.  

Denis Kinane, Chief Medical Officer at Cignpost Diagnostics