In this paper, we present the results of a comprehensive COVID-19 survey of aquatic athletes who participated in the FINA 19th World Championship, which was the first world aquatic championship after major COVID-19 waves subsided. The principal findings of this paper include a high SARS-CoV-2 infection rate in athletes, with a higher incidence in team sports. The symptoms were mostly mild; however, long COVID syndrome was detected in 10% of the athletes. High symptom counts predicted a higher burden of long COVID syndrome. The second SARS-CoV-2 infection was mostly reported to be milder, with fewer symptoms and fewer missed training days than the first. The vaccination rate among this athlete population was high (92%), predominantly reporting mild post-vaccination symptoms. Mood changes and subjective drop in performance were important in the athletes’ overall pandemic experience.
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Infection rates and clinical characteristics
The COVID-19 disease and its sequelae have affected all levels of society, including the field of professional sports. The course of infection, combined with quarantine and confinement requirements, took a toll on the quality of life of athletes during the period of the pandemic. Reduced physical activity, impaired sleep quality, altered daily activity, increased anxiety, diminished cardiorespiratory fitness, and less desirable nutritional habits were among the reported consequences26,27,28,29,30. The infection affected 8–10% of the overall population, which proved more frequent in athletes31. One of the largest longitudinal studies from 2020, which summarised the results of almost 10,000 athletes from 13 universities, and found a SARS-CoV-2 infection rate of 30.4%, with a 2.3% prevalence of myocarditis32. In this study, the overall COVID-19 infection rate was 49.4%, with 3% of severe cases requiring hospitalisation.
The higher perceived infection rate may have been due to an extended observational period and more rigorous screening of athletes. Vigorous training may also impair immune function rendering athletes more susceptible to infections with post-exercise immunosuppression through an altered helper T-cell response and elevated stress hormone levels33,34. This has distinct application to a cohort of elite aquatic athletes preparing for world championships.
We concluded that close physical contact is one key factor driving the increased SARS-CoV-2 infection rates, particularly among athletes in team sports. Indeed, in this study, the occurrence of infection was the highest among water polo players and artistic swimmers while the lowest among open water swimmers. This aligns with reports of higher transmission of SARS-CoV-2 infection in team sports35,36.
In a Swiss COVID-19 survey assessing the prevalence and symptoms of the infection in elite athletes, the disease prevalence was less than 20%, with a male predominance35. Interestingly, in our cohort, female athletes had higher rates of SARS-CoV-2 transmission, but symptom severity did not differ between the sexes. Other authors suggest that young female athletes have a lower risk of severe symptoms and remain dominantly asymptomatic37,38.
Similarly, most studies have reported mild to moderate COVID-19 symptoms in athletes32,35,39,40,41. In our findings, the main symptoms were headache, fever and cough. Different SARS-CoV-2 variants have been linked to distinct symptom profiles and diseases. In a prospective registry of collegiate athletes, the most common symptoms detected between September and December 2020 were loss of taste or smell, headache, muscle pain, cough, fatigue and fever, similar to our data gained about the second half of the year 202039.
However, the exact missed training time interval is scarcely reported in athletes and may be dependent on several factors. In our findings, most athletes missed 1–2 weeks of training which might involve the role of quarantine, symptom severity, and closure of training sites, among others. According to Krzywanski et al.’s findings, COVID-19’s impact has been higher than other respiratory tract infections regarding missed training. The surveyed elite Polish athletes (n = 1073) reported that 12–13% lost training days due to COVID-19, which is expressly lower than what the multinational aquatic athletes showed42. Schwellnus et al. associated symptom clustering with different return-to-play times and compared COVID-19 with other acute respiratory illnesses. They found that return-to-play after COVID-19 was significantly longer than in the other group (IQRs 16–40 vs 7–22 days) and, generally, symptom cluster is associated with prolonged missed training times with excess fatigue in particular43.
Long COVID
Our study detected long COVID syndrome in 10% of the athletes. A systematic review and meta-analysis of 43 studies covering 11,518 athletes reported a long COVID syndrome rate of 8.3%7. A study including 4186 post-COVID patients assessed the prevalence of long COVID syndrome in the average population and found a slightly higher incidence (13.3%) of persistent (> 4 weeks) symptoms8. Our previous findings in a prospective cohort of 322 athletes showed a long COVID occurrence of 8%, highlighting differences between age groups, where adult and master athletes were more likely to develop long-standing symptoms5. We previously showed that increasing age and a worse symptom severity score predicted long COVID occurrence. Nevertheless, in this dataset, including predominantly young adults, we found that only acute symptom count was an independent predictor of developing long COVID.
Reinfection
The SARS-CoV-2 reinfection of athletes has not been extensively described in the literature, with case reports and low case number studies available44,45. Good et al. reported that the reinfection rate was as low as 0.8% in a pre-omicron (Delta wave) student-athlete cohort. In our study, the reinfection rate was 13%, with fewer and milder symptoms and fewer missed training days than the first infection. This phenomenon may be related to the different SARS-CoV-2 variants22,46,47. Another explanation might be that athletes encountered the second infection with an already primed immune system either through prior infection or vaccination. Another insight might be that vaccine roll-out helped mitigate the disease severity. In addition, our relatively high reinfection rate may be explained by the fact that most SARS-CoV-2 infections occurred in the first half of 2022 during the Omicron variant outbreak. Furthermore, elite athletes usually have strict medical control due to the pre-competition screenings and regular health check-ups; thus, it is more likely that mild or asymptomatic (re)infections are recognized. In contrast, the reinfection rate in the non-athletic population was relatively low until the Omicron era37,48.
Vaccination
Almost all (94%) of our participants had been administered at least one dose of a COVID-19 vaccine, and 92% received the second shot as well. With a high vaccination rate, the athletes reported a relatively low burden of adverse side effects and only a few major ones, similar to the general population21. The duration of side effects was generally short, lasting no more than three days. An infographic paper by Rankin et al. found that the vaccination in athletes was generally well tolerated, the majority of the side effects were mild, and the missed training period was as low as 4 days24,49. Oudjedi et al. found that 55% of the surveyed Algerian athletes (n = 273) reported side effects after COVID-19 vaccination, of which fever and local pain were the most prevalent. These findings generally align with our data. Nonetheless, for athletes with the dominant use of the upper extremities, the timing of the vaccine administration may be decisive due to the possible local side effects24.
In spite of the increasing SARS-CoV-2 vaccination rate, the number of infected cases also surged, which may reflect the lower efficacy of the vaccines against the newer Omicron variants as described in the literature47,50,51.
Psychological aspects
The COVID-19 pandemic has brought uncertainty to the lives of athletes and non-athletes, leading to stress, anxiety, depression and other mental disorders52. A study examining 310 athletes from different continents and diverse sports disciplines found that maladaptive perfectionism was related to numerous mental health indicators. They also concluded that competitive athletes showed signs of a negative emotional state during the pandemic. Even so, the anxiety, stress, and depressive symptoms were less prevalent in athletes with proper coping strategies53. Based on our results, mood changes and subjective performance drop correlated closely with the overall experience during the pandemic; 36% of the athletes reported needing psychological support. Female athletes reported slightly worse mood change scores compared to male athletes. Several studies found similar data regarding the post-COVID mental health of female athletes20,38,54,55. Notably, half of the athletes questioned did not need psychological support. However, it is not apparent whether this is reflective of adequate coping skills—such as cognitive restructuring and emotional calm—or not. Also, 17% of the surveyed athletes were unable to obtain psychological support despite their need, reflecting the importance of providing appropriate psychological help in the context of sport.
Limitations
This self-reported, retrospective study is based on a monolingual (English) survey, and the language barrier may have impacted the answers of non-native English speakers. In addition, we do not have any information about the type and methods of SARS-CoV-2 testing, nor could we confirm the validity of other reported health-related variables. Consequently, the potential lack of accuracy and incompleteness of the answer sheets may have slightly influenced the data quality. In addition, the exact date of any positive tests could not be verified through institutional medical sources.
