Covid is a highly contagious virus that spreads and lingers in the air, and we have athletes in close quarters without any virus control procedures [1] (other than the Olympic organizers providing hand sanitizer [2], which is an odd choice for airborne virus prevention).
Given lack of testing and that many countries (including European countries) are seeing Covid surges right now, I think it's highly likely that most competitors are competing with either current or recent Covid infections affecting their peak performance capacity.
Edit: I wouldn't suggest it's the sole cause of performance issues. But for an entire article on the topic of swim performance to completely ignore multiple reports of viral infection from top performers seems a glaring omission.
To be clear, there is no scientific consensus on the term "surge". It is purely editorial, in my view. Iff you believe KFF.org, there trend lines show a sharp fall in the last six months here: https://www.kff.org/coronavirus-covid-19/issue-brief/global-...
Sidestepping nomenclature bikeshedding, healthcare organizations are seeing an increase in patient load which seems like a reasonably tactical datapoint that there's a meaningful increase over the last couple months.
Google is your friend; this [1] is but one France-specific example of coverage. You can find many similar articles in jurisdictions across Western Europe raising concern specifically in the last month or two.
Edit:
Many jurisdictions stopped collecting and/or sharing robust datasets in 2023 (KFF even calls attention to this). This often means digging through opaque reports to get useful data.
Here's an example [2] from the UK government, in PDF format, but bottom of Page 10 looks pretty "surge-y" to me over the last couple months and not yet at peak.
Edit:
Another example of good data horrible to access. Scotland wastewater monitoring [3] I can't provide a direct link; have to click on "Respiratory pathogens" and the first chart is wastewater monitoring; July 2024 shows the highest "surge" in levels since 2022.
Given lack of testing and that many countries (including European countries) are seeing Covid surges right now, I think it's highly likely that most competitors are competing with either current or recent Covid infections affecting their peak performance capacity.
Edit: I wouldn't suggest it's the sole cause of performance issues. But for an entire article on the topic of swim performance to completely ignore multiple reports of viral infection from top performers seems a glaring omission.
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1: "The 29-year-old does not have to isolate from other athletes and does not have to test negative before competing again": https://www.espn.com/olympics/story/_/id/40672610/olympics-2...
2: "For now, nothing has been put into place by the organizing committee … but hand sanitizer is available in its clinics and restaurants.": https://www.cbsnews.com/news/2024-paris-olympics-covid-cases...