The COVID-19 pandemic is sweeping the season. A number of riders have fallen ill this week at Paris-Nice and Tirreno-Adriatico with respiratory illnesses that appear to be unrelated to COVID.

The rate of falls in both World Tour races, especially Paris-Nice, has been alarming.

On Thursday morning, before the fifth stage of the French race, 18 riders failed to start. At least 13 of these (and probably several more) were due to illnesses such as influenza, sinusitis, and bronchitis.

In Tirreno-Adriatico, Italy, the situation was less serious, but Peter Sagan (Total Energy) left the race on Wednesday with "fever and stomach problems" and Ruben Guerriero (EF Education - Easy Post) left the race with "cold-like symptoms."

No positive cases of COVID-19 have yet been found in either race.

"Both Tirreno and Paris-Nice teams have been hit by the same old flu. Fever, chills, etc., COVID is negative," EF boss Jonathan Vaughters wrote on social media.

"I think because we've been quarantining ourselves for the last few years, we've all forgotten about the flu and are probably less resistant.

In Paris-Nice, the wave of illness hit Israel Premier Tech particularly hard, and the team left for stage 5 with just one rider.

Rudy Barbier and Mads Wurz-Schmidt left after the first stage, Guillaume Boivin left after the third stage, and now Carl Fredrik Hagen, James Piccoli, and Tom Van Asbroeck were deemed unable to continue on Thursday.

Hagen and Piccoli are suffering from "non-COVID virus symptoms" and Van Asbroeck from a "respiratory infection." According to the team, "all three have repeatedly tested negative for COVID and are in isolation."

EF Education-Easy Post was another team that lost three riders on Thursday morning, with Nielson Powles, Stefan Bissegger, and Jens Keukerer leaving. The team reported that Powles had bronchitis, but no reason was given for the other two, although it was noted on the Paris-Nice website that Bissegger was "ill."

Quick Step Alphavinir's duo of Yves Lampaert and Zdenek Stibal are also two important riders in the Belgian team's quest for the spring classics. Lampaert has been suffering from a sinus infection, while as for Stibal's retirement, "Take care: 'Take care, Zdenek.' [A few days after Barlain Victorious' teammate Sonny Colbrelli left with bronchitis, Gino Mader left with a fever. Meanwhile, Nils Pollitt (Bora-Hansgrohe) has sinusitis and Clément Champoussin (AG2R Citroën) has the flu.

Kevin Vermaquet (DSM) and Amaury Capio (Arkea Samsic) will miss stage 5 due to unspecified health problems, and the Alpecin Phoenix trio of Jay Wein, Cristian Sbaralli, and Jonas Ricart have so far received no team not received an explanation.

On top of that, Matteo Trentin (UAE Team Emirates) and Dylan Groenewegen (BikeExchange-Jayco) did not start stage 5, although this was due to a crash early in the race.

The string of abandonments brought the number of early eliminations in Paris-Nice to 28. Defending champion Max Schachmann (Bora-Hansgrohe) and Ben O'Connor (AG2R Citroen) were among the big names who pulled out early in the race due to illness.