# COVID-19 infection and return-to-play outcomes of elite athletes in Japan: a retrospective descriptive study

## TL;DR

This study examines how COVID-19 affected elite Japanese athletes and how quickly they returned to play after infection.

## Contribution

The study provides insights into the impact of the Omicron variant on elite athletes and their return-to-play timelines.

## Key findings

- Most infections occurred during the Omicron wave, with indoor athletes being more affected than outdoor athletes.
- The median return-to-play time was 10 days, with most athletes resuming within 28 days.
- Symptomatic cases were more common than asymptomatic ones, with fever being the most frequent symptom.

## Abstract

To describe the characteristics of COVID-19 among elite Japanese athletes and their return-to-play (RTP) time.

We retrospectively reviewed clinical records at the Japan Institute of Sports Sciences between June 2022 and May 2023. Elite athletes who underwent periodic health examinations were examined by a physician to confirm COVID-19 history, symptoms and the RTP time.

Of 994 athletes, 456 had a COVID-19 history (mean±SD, 23.3±4.6 years; 56% male). Most infections occurred during the sixth wave (Omicron variant), followed by the seventh and eighth waves, with 88% recorded after the fifth wave. Indoor athletes were more frequently affected than outdoor athletes (306 vs 150, p<0.05). Badminton athletes were the most commonly affected athletes (16%), followed by volleyball (10%) and handball (7%). Among those with a history of COVID-19, 89% reported symptoms, while 11% were asymptomatic. Fever was the most common symptom (80%), followed by sore throat (58%) and cough (44%). The median (IQR) RTP time was 10 (7–14) days. Overall, 472 athletes resumed play within 28 days, while 20 returned after 28 days. RTP delays were more frequent before Omicron (9/59 athletes) than after (11/433 athletes, p<0.05).

COVID-19 was more common among indoor sports athletes, primarily during the Omicron wave, with most cases being symptomatic but resolving quickly. These findings likely reflect factors such as close-contact training, immune changes during intensive training and international travel and may help characterise COVID-19 outcomes in elite athletes.