July 15, 2024

False positive

With complicated and ever-changing testing rules still in place for many destinations and unsuspecting business travellers getting caught out, we spoke to two experts from World Travel Protection

The industry breathed a sigh of relief when the UK relaxed its entry requirements for fully-vaccinated travellers but many other destinations still have Covid testing regimes in place.

Rules vary depending on the vaccination status of the traveller, the destination they are travelling to or from, and where they might be stopping on the way.

To further muddy the waters, it’s not uncommon for a PCR test to throw up a false positive and there are several different interpretations about what ‘fully-vaccinated’ actually means.

We asked two experts at World Travel Protection – Dr Neil Slabbert, Regional Chief Medical Officer, Asia Pacific, and Dr Joel Lockwood, Regional Chief Medical Officer, UK and Americas – to throw some light on some of the complexities.

Is a positive PCR result a reliable indicator of whether someone is infectious?

Dr Neil Slabbert

Dr Neil Slabbert: “The international consensus on how long someone remains infectious after a positive Covid test has decreased over the last few months in the changed Covid landscape due to Omicron. Depending on where you are in the world and on your vaccination status, you can return to work anywhere from 5 to 14 days after a positive Covid test, however, repeat PCR tests can remain positive for up to eight weeks post-infection. The PCR swab tests for viral genetic material but can’t differentiate live virus from particles of dead virus, which is normal to shed after you’ve cleared Covid. Hence, you could have recovered from Covid for some time but still be shedding dead virus, not be contagious, and have a false positive PCR result.”

Dr Joel Lockwood

Dr Joel Lockwood, Regional Chief Medical Officer, UK and Americas, World Travel Protection, adds: “At the very beginning of Covid, we required negative tests for healthcare staff to return to work and came across the problem Dr Slabbert outlined where staff who felt fine had recurrent positive tests often lasting months. Eventually, a non-tested base clearance strategy was then used. This isn’t as objective as a PCR test, which is either negative or positive as it relies on you recovering from a recent infection. For that reason, situations like travel where airlines have to check passengers still require PCR testing. Governments at the destination site often require evidence of negative PCR tests and departing airports and airlines also require this in many jurisdictions.”

So, what about those travellers who get a false positive because of a previous infection?

Dr Neil Slabbert “Because PCR tests are giving false positives, many airlines have introduced a Certificate of Recovery where one can fly with a positive PCR if seven days has elapsed since your positive test and you have had no fever or Covid respiratory symptoms in the preceding 72 hours. Another potential issue, however, are those people who have no idea they have actually had Covid at all because they have been asymptomatic, and therefore can’t provide a Certificate of Recovery since they have no previous positive result to date their infection.”

Dr Joel Lockwood: “Currently a limited number of locations are accepting proof of recent infection as evidence of immunity and typically this is legislated. But while an end destination such as UK might not require testing, transit countries like Singapore will.”

Is it an airline’s responsibility to verify the PCR test results or is it down to the authorities in the destinations they fly to?

Dr Joel Lockwood: “Governments at the destination site require evidence of negative PCR tests and departing airports and airlines also require this in many jurisdictions. It is important for travellers to check local guidelines as the requirements are frequently changing.”

Dr Neil Slabbert: “As Dr Lockwood has mentioned, pre-travel Covid testing is country specific. While the end destination countries like UK might not require a test, transit countries like Qatar or Singapore might. Airlines board passengers according to the rules of the country they are flying to, which might not be the traveller’s end destination, even if flying on the same airline.”

Apart from the UK, which other countries have now scrapped the PCR requirement for arrivals and are others likely to follow?

Dr Joel Lockwood: “Entry requirements for each country vary depending on a number of factors (where one is travelling from, vaccination status, other countries recently visited) and change frequently. Travel managers should research the requirements for testing and quarantine prior to departure.”

Dr Neil Slabbert: “Countries will scrap Covid testing requirements with time for vaccinated travellers as Covid is now seen as endemic. However this may change if another variant of concern emerges or if a massive spike in case numbers occurs. The challenge for countries is how they respond to unvaccinated travellers.”

What would your advice be for travel managers responsible for ensuring their travellers meet the requirements?

Dr Joel Lockwood: “Ensure employees are following up to date and reliable information regarding Covid testing and vaccination prior to travelling and quarantine requirements during travel. Since the requirements are so complex and change frequently, we recommend travel managers consult their government’s webpage for the most accurate information.”

Dr Neil Slabbert: “I agree, I have nothing to add.”

Is it getting easier?

Dr Joel Lockwood: “While the information is confusing at times, travellers have grown accustomed to the dynamic landscape and challenges that travelling in the time of Covid brings.”

Dr Neil Slabbert: “Uncertaintly has decreased as over the last two years as reliable sources of information have become available and travellers have increasingly become familiar with this new reality. Information output and timing has also improved from government health departments.“

Are there many cases of people having to cancel a business trip at the last minute because they are still testing positive despite having had recovered from Covid?

Dr Joel Lockwood: “Yes. This is most commonly seen in areas of high Covid infection.”

Dr Neil Slabbert: “Some countries and their airlines do not recognise Certificates of Recovery. Travellers might also change their travel plans if a country is experiencing high Covid case numbers, such as is currently happening in Hong Kong.”

The term ‘fully-vaccinated’ seems to be different depending on the country and what stage it has reached with its vaccination programme. Is that true?

Dr Neil Slabbert: “An issue certainly is – what is ‘fully vaccinated’? There seems to be a move toward fully vaccinated including a third or fourth vaccine dose if you’re in a vulnerable group, as recent studies have shown immunity to Omicron decreases at 10 weeks. Pfizer has also started developing an Omicron-specific vaccine, to be ready late March. Anthony Fauci, Chief Medical Advisor to the President of the US, says it’s probably not necessary but prudent, but who knows with a new Omicron subvariant BA.2 that is currently being monitored. BA.1 is the original Omicron strain. BA.2 shares 32 mutations with the original Omicron, but BA.2 also has 28 mutations which are different.”

Dr Joel Lockwood: “Many countries including Canada and Israel have introduced third and even fourth vaccine doses, especially for those in vulnerable patient groups. Other developing nations are struggling to even get first doses for their citizens.”

What is the future for Covid testing and travel?

Dr Joel Lockwood: “In the setting of a pandemic, it is difficult for governments and local health authorities to maintain policy that reflects current best science and evidence. Travel and testing restrictions placed where case counts are rising should be re-evaluated when cases fall. It will be interesting to see if there is a delay re-evaluating these policies as the Omicron wave subsides.”

Dr Neil Slabbert adds: “I believe the world will soon follow the UK and drop all PCR travel testing requirements for the vaccinated as Covid is now truly endemic. However, the unvaccinated is where the conundrum lies.”