Several months ago I wrote that as countries started requiring negative Covid-19 tests in order to travel people would start faking negative test results.
- The harder it is to get a test, the more likely faking results will be. It’s not primarily about ‘people with Covid-19 trying to travel’ as much as people looking for an easier way to get through the requirement.
- The more requirements, such as using specific test providers or specific tests, and the scarcer those tests are, the more likely faking results becomes.
A simple testing regime, where rapid antigen tests are accepted from any provider and can be offered even at the airport prior to flights is going to mean the least faked results. So even if antigen tests aren’t the ‘gold standard’ PCR tests they need to be judged against PCR tests, including faked tests. 95% of passengers on a single flight faked their tests.
- PCR tests are highly accurate they take more time and pick up very small trace amounts of viral RNA even dead virus long after someone is infectious.
It takes “weeks or months” for the debris to clear, says Mina. “The average duration people are PCR positive is about 25 to 35 days,” he says. “The average time people are infectious is between four and eight days.” Most of the people walking around with PCR-detectable viral RNA in their nasal passages are post-infectious.
- Cheap lateral flow tests can be done in half an hour, and are great for picking up those that are currently infectious. They “only return a positive result for about four to eight days in the infection cycle.”
For most purposes lateral flow tests are good enough, and give you the information you’re most interested in: can this person be around others right now? But they’re likely to miss some people who will become infectious yet still have a lower viral load. They don’t offer a guarantee for ‘test and release’ but would work better for ‘quarantine for a few days and then test’.
In other words, there are tradeoffs. Ultimately testing needs to be available to find cases and encourage people to isolate and scaling lateral flow tests is far easier than PCR tests, such that you can do more tests and do them frequently.
“I just fired up photoshop and changed the date,” wrote one man who had doctored results for an entire group of friends to Motherboard. “Fun fact, the document [test result] was in French whereas they were in Sweden the day it was supposedly made, but they didn’t see a problem in that.”
The other person took a slightly less sophisticated route and changed the date of an old test with Microsoft Paint for his vacation to Southern Europe.
In both cases it wasn’t the difficulty getting tested that was the problem, it was the cost of the tests that drove them to fake their results. That’s an argument for cheaper tests.
A negative Covid test scalper was just arrested at London Luton airport too. We can all react with shock and horror at the individual, but it points to a problem in need of solving too. If you aren’t going to shut down travel altogether, then any testing policy needs to weigh tradeoffs.