Inge van der Heijden, who was forced to miss the Dutch Championships road race in Drenthe on Saturday due to a positive test for COVID-19, announced on Instagram (opens in new tab) that the retest was negative, raising questions about the reliability of PCR testing

"The first time I saw the test, it was negative.

"Confirmed negative last Friday.

"I tested negative last Friday and had no symptoms of infection, but to my great dismay, I suddenly tested positive on Wednesday. We discussed it and decided to add a PCR test yesterday. It was as expected.

Now the U23 cyclocross world champion respects the quarantine but has concerns about the rest of the season.

"This relates to the road national championships, which is not the most important thing for me as a cyclist, but as far as the next 'cross season, I'm worried about the classification races.

For riders competing in the upcoming Tour de France, the stakes are even higher. There is a convention that if two riders from the same team test positive, the entire team is forced to withdraw.

PCR testing is generally considered very reliable, with a low false positive rate (confirming that someone is infected with the virus when they are not actually infected). However, because the test amplifies trace amounts of genetic material from the virus, false positives can occur due to cross-contamination during sample collection and processing.

A negative follow-up test result would corroborate a false positive from a previous test.

PCR testing can also lead to missed infections and false-negative results if Van der Heijden says he has no symptoms, even though he has not yet produced enough detectable viral particles in the early stages of infection.

Due to Wednesday's positive test, Van der Heijden's teammates Yara Castellain and Anique van Alphen withdrew from the championships because they did a reconnaissance ride with Van der Heijden.

Similarly, Team Ineos withdrew from the Italian Championships after Leonardo Basso, who was on a reconnaissance ride with teammates Filippo Ganna, Gianni Moscon, and Salvatore Puccio, tested positive for the virus.

Van der Heiden is not the first cyclist to test false positive: Omer Goldstein (Israel Startup Nation) tested positive for coronavirus, and he and two teammates withdrew from the Vuelta a Burgos in July.

Other players who tested positive for COVID-19 without symptoms include Hugo Uhl (Astana), Larry Warbas, and Sylvain Dillier (AG2R La Mondiale).

Dillier tested negative in subsequent tests, questioned the coronavirus protocol, and told the Swiss newspaper Blick that he was "the healthiest person on earth" and that what happened to him was "not right."