key: cord-0907108-gl3nadcu authors: Schumacher, Y. O.; Tabben, M.; Hassoun, K.; Al Marwani, A.; Al Hussein, I.; Coyle, P.; Abassi, A. K.; Ballan, H. T.; Al Kuwari, A. J.; Chamari, K.; Bahr, R. title: Resuming professional football during the Covid-19 pandemic in a country with high infection ratesA prospective cohort study date: 2020-11-18 journal: nan DOI: 10.1101/2020.11.17.20233023 sha: 3e9c3dea3101efaf6bc33e9f21b7b9e5448abf0c doc_id: 907108 cord_uid: gl3nadcu Objectives: The risk of viral transmission associated with contact sports such as Football during the COVID-19 pandemic is unknown. The aim of this study was to describe the development of infective and immune status of professional football players, team staff and league officials over a truncated football season resumed at the height of the Covid-19 pandemic in a country with high infection rates and to investigate the clinical symptoms related to Covid-19 infection in professional football players. Methods: Prospective cohort study of 1337 football players, staff and officials during a truncated football season (9 weeks) with a tailored infection control program based on preventive measures and regular SarS-CoV-2 PCR swab testing (every 3-5 days) combined with serology testing for immunity (every 4 weeks). Clinical symptoms in positive participants were recorded using a 26-item, Likert-scale-based scoring system. Results: During the study period, 85 subjects returned positive (cycle threshold (cT)<30) or reactive (301.5 m of another player for the vast majority of the game (8) and encounters are brief (tackling and heading duels). Still, the heavy, unprotected breathing during exercise generates more droplets than normal respiration, increasing the risk of exposure (9). Meyer et al. (10) have recently described the successful reopening of the German professional league, but in a situation where the risk of viral transmission was low, with only about 5 new cases per 100 000 inhabitants per week in Germany. We wanted to describe the development of infective and immune status of professional football players, team staff and league officials over a truncated football season resumed at All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint 3 the height of the Covid-19 pandemic in a country with high transmission risk, as well as describe the clinical symptoms related to Covid-19 infection in professional football players. Such data are critical when planning for major sports events during a pandemic. All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. To allow resumption of the football league, the QSL decided in May 2020 to implement a return-to-competition protocol to complete the season (11) . The mainstays of this protocol were strict hygiene measures and regular testing. All players, staff and referees signed written commitments to adhere to these measures; breaches were subject to fines. The protocol included an initial two-week hotel quarantine period, where the teams trained without physical contact. Upon completion and for the rest of the season, players and staff were allowed to live their normal life with a signed pledge to adhere to home quarantine when not training or playing and limit social contacts whenever possible. Violations were subject to fines from the league. Other country-wide measures implemented by the Ministry of Public Health of Qatar also applied, such as temperature checks, social distancing, wearing a mask outside training and matches, frequent hand hygiene. Club facilities such as showers and recovery areas were closed; players were advised not to use changing rooms and change and shower at home. Indoor activities such as team meetings or gym sessions were limited to the necessary. After the quarantine period, teams resumed playing matches, first 1-3 friendly matches, then the final official matches needed to complete the season, with the last match on August 21 st . All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint 5 Covid-19 testing protocol Before entering and on the day of exiting the quarantine period, players and staff members were submitted to a polymerase chain reaction (PCR) nasopharyngeal swab test (one nasal swab, one pharyngeal swab), performed by a team of specifically trained, experienced nurses using flocked swabs in 3 ml universal transport medium. This was repeated every 3-5 days until the end of the season, scheduled two days before every match. When exiting the hotel quarantine and then approximately every 4 weeks, serum samples were collected for SARS-CoV-2-specific antibody analyses using standard equipment and procedures. The timeline and testing schedule are illustrated in figure 2. We report test results from two phases, the quarantine phase (entry and exit) and the training and match phase (after exit until the first test done during the week after the last match on August 21 st ). 30), reactive (cT >30 and <40), negative or inconclusive. Reactive was added as a category to identify cases where the likelihood of transmission was deemed low and being in recovery high for most subjects (12-All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. Results were communicated automatically to the tested person through the national Covid-19 tracking phone application (mandatory for all inhabitants of Qatar) and, in addition, through their team physicians. If a subject returned a positive or reactive PCR test, he was immediately removed from his team and underwent an isolation protocol implemented by the Ministry of Public Health of Qatar, consisting of 14 days of quarantine for positive cases and 7 days for reactive cases. Upon completion of the quarantine, subjects returned to their normal function within the team and did not have to undergo any further PCR testing (15), but still underwent regular serology testing. Inconclusive samples did not result in any consequences; subjects were just retested on the next scheduled testing date. Contact tracing was performed by the research team for each case to identify the potential source of infection and other possibly contaminated subjects. Symptoms were scored for each positive or reactive player using a 26-item symptom score, where symptoms were grouped in three categories: 1) Nose and throat symptoms, 2) Chest and other head/neck symptoms and 3) Whole-body symptoms. The list of specific symptoms is shown in Table 2 . Players were asked to rate, on average, how severe any symptom All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint 7 reported was, using a 7-point Likert scale where 1 was "very mild", 3 "mild", 5 "moderate" and 7 "severe", as well as for how many days each symptom lasted. They could also report "other symptoms". An overall symptom score was generated as the sum of the scores for each of the three categories. Forms were completed by team physicians with the player present, when he was asymptomatic and had returned to play. Test results were transferred from the central laboratory to a database adhering to local data safety protocols and analyzed using Tableau Prep Builder 2020 and Tableau Desktop 2020 (Seattle, USA). Population reference data were obtained from the daily Covid-19 numbers officially communicated by the Ministry of Public Health in Qatar throughout the pandemic. We estimated the national incidence of Covid-19 cases in Qatar as the number of PCRpositive or -reactive samples per 100 000 residents per week based on a population of 2.8 million (16) . For players, we calculated incidence per 100 000 players per week based on the number of players tested during the study period. Participating players and staff were not involved in the planning of this research study. The study was approved by the Institutional Review Board of Aspire Zone Foundation (Application number E202009011). All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint As shown in Figure 1 , the daily number of new PCR-confirmed cases in Qatar was 47 per 100 000 persons on the first day of the study (June 8 th , 2020), receding gradually during the study period to 17 cases per 100 000 on September 1st. The same was the case for the proportion of positives or reactives among PCR samples taken nationally, declining from 29% to 4%. All 12 Division-1 teams and 5 Division-2 teams were included in the study (player age: 26.3±5.3 years (mean ± standard deviation); 54 nationalities). Teams were quarantined for 21±3 days and they resumed inter-team match play 9±6 days after leaving quarantine. Division 1 teams played 102 matches, corresponding to 9±0.5 matches per team; Division 2 teams played 29 matches, 6±2 per team. A total of 757 persons were tested at entry into the quarantine period, with 3.6% positive (N=23) or reactive (N=4) samples, including 7 positive tests among 434 players (1.6%) ( Table 1 ). The exit tests from quarantine, where 719 individuals where tested, revealed an additional 9 positive or reactive samples (1.3%). Of these, 5 were players (1.2%). During the match phase, between the quarantine exit test and the first test after the final match, 1 167 individuals were tested, with 4.2% positive or reactive tests. Of these, there were 24 positive or reactive tests among the 549 players tested (4.4%). This means that during the study period, excluding the entry screening tests, there were 29 positive or reactive cases among players, corresponding to 457 cases per 100 000 players per week. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint 9 Contact tracing revealed that, of the 36 players with positive or reactive PCR tests during the observation period, 20 did not know where or through whom they might have become infected. For 5 players, the infection could be traced to positive family members, 9 had social interactions (dinner, celebrations) with friends who subsequently returned positive tests. One semi-professional player was infected by a colleague at his workplace. The only confirmed transmission in a football team setting occurred from a physiotherapist (likely infected by his wife who works in the public health sector as a nurse), who subsequently infected one of the players he was treating (other players treated by the same physiotherapist returned negative tests). Of the 36 infected players, 15 reported having been symptomatic, mainly with mild symptoms lasting <1 week ( Table 2) . None of the 85 individuals (players, staff and referees) testing positive or reactive at any time during the study required hospital admission or medical attention other than limited symptomatic treatment. All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint Our study is the first to investigate the risks associated with Covid-19 infection from resuming professional football during the peak of the pandemic in a country with high infection rates. The data show that, with the return-to-competition protocol instituted, the season was completed with low risk to player health. The infection rate did not exceed what was expected given the viral transmission risk in Qatar at the time, we did not find any evidence for SARS-CoV-2 transmission during training or matches, symptoms were absent or mild in infected players and staff and there were no hospitalizations or deaths. All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint 11 Infection pathways As expected from the asymptomatic course of a large number of infections, we could not determine the source for more than half of our cases. The common denominator for the remaining cases is that the infection mainly stemmed from social contacts outside sports, such as friends, family or social events. In such settings, the adherence to preventive measures such as social distancing, wearing a mask, hand hygiene is often less strict, thus increasing the risk of infection. In our protocol, we did not find any evidence of transmission during training or matches. It may be argued that we were unable to trace any infection related to football because of the screening and prevention program itself, i.e. that any positive cases were removed from their team before further infections occurred. While this was obviously the purpose of the return-to-play protocol, some issues need to be considered: A large number of cases were asymptomatic, thus not picked up at the daily routine temperature and symptom screening performed by the team physician. Therefore, some infected players likely mixed with their peers before being detected by our testing program. The PCR tests were typically scheduled two days before each match. Based on the known course of infection of SARS-CoV-2, it is therefore possible that subjects returned a negative PCR test at their pre-match screening despite being infected. Two days later, on match day, they would likely have entered the infectious phase. Therefore, it is likely that some already infected players were not immediately identified by our screening program. Indeed, one of our cases tested negative two days before his match. He was again tested (outside our program) in the morning of the match at his workplace due to a suspicious case among his colleagues and returned a positive test with a cT value below 20. He was asymptomatic throughout and as the results of the positive workplace test only became available the next day, he played the full match despite being (unknowingly) positive and All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint 12 likely highly infectious. None of his teammates or any member of the opposing team tested positive or reactive within the next two weeks. In another event, three staff members and one player from another team were infected by another guest during a private dinner. The dinner was held in the evening of one of the testing days, where staff and players had tested negative. They continued to mix with their teams, still tested negative in the next test 4 days later and were only found positive or reactive 7 days later. None of their teammates and only one staff member was subsequently found to be infected. These accounts illustrate that even with a tight testing program there is a risk for having positive and potentially infectious subjects in the population. However, they also support the hypothesis that the infection risk is highest during unprotected exposure in closed spaces, while it is limited when outdoors, even when there is close physical contact between infected and non-infected subjects. In fact, "contact", as per infection control criteria, is limited during football matches. During a 90-min match, a player spends only approximately 30-90 seconds in close proximity (<1.5 m) of other players. (8, 17) . On the other hand, aerosol droplet production is increased with heavy breathing while exercising (9) . There are few descriptions of spreading events related to sports in the literature: Atrubin et al. (18) described an ice hockey match, where 14 out of 22 players and one rink staff member were infected by one player during a single match. Other reports link infections to fitness dance classes and squash facilities (19, 20) . The main difference between these spreader events and our setting is that they occurred indoors in relatively restricted spaces, whereas our athletes played and trained outdoors. Interestingly, two of the three reports (dance and squash) represent non-contact sports. This supports the hypothesis that respiratory droplets (present in all settings) represent the main transmission mode also during sporting events, but that an outdoor setting with good air circulation attenuates risk. All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint 13 Thus, when implementing a return-to-play protocol designed to prevent infections, the risk of SARS-CoV-2 transmission during outdoor football training and matches was low. The infected players showed no or only mild symptoms ( Table 2) Our data suggest that major sporting events played outdoors involving close contact between athletes represent a limited risk for SARS-CoV-2 infection and severe illness when preventive measures are in place, even if the risk of viral transmission in the general population is high. These data may guide organizers of major sports events such as the Olympic Games or continental football championships in their decision-making. All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint Evidence before this study Professional and leisure team sports were suspended as measures of public health in most countries to prevent the spread of SarS CoV2. There is only limited information if contact sports played outdoors such as football/soccer indeed represent an increased risk of viral transmission. The only previous study was conducted in an environment of low viral prevalence. We describe viral transmission and the clinical picture of Sars CoV 2 infections in professional football players and staff in a country which had, at the time of play, among the highest infection rates in the world. Our data shows that with preventive measures in place, the risk of transmission during training and games is low. Policy makers might consider our results in view of public restrictions to limit viral spread, but also for the assessment of infection risks in the organization of major Sports events such as Olympic Games. All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint The Corresponding Author has the right to grant on behalf of all authors and does grant on behalf of all authors, a worldwide licence to the Publishers and its licensees in perpetuity, in all forms, formats and media (whether known now or created in the future), to i) publish, reproduce, distribute, display and store the Contribution, ii) translate the Contribution into other languages, create adaptations, reprints, include within collections and create summaries, extracts and/or, abstracts of the Contribution, iii) create any other derivative work(s) based on the Contribution, iv) to exploit all subsidiary rights in the Contribution, v) the inclusion of electronic links from the Contribution to third party material where-ever it may be located; and, vi) licence any third party to do any or all of the above." YOS (the lead author) affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as originally planned (and, if relevant, registered) have been explained. All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint WHO Declares COVID-19 a Pandemic The coronavirus pandemic in five powerful charts A Game Plan for the Resumption of Sport and Exercise After Coronavirus Disease 2019 (COVID-19) Infection Current Perspectives on Coronavirus Disease 2019 and Cardiovascular Disease: A White Paper by the JAHA Editors Can exercise affect immune function to increase susceptibility to infection? Factors associated with COVID-19-related death using OpenSAFELY Infection fatality rate of SARS-CoV-2 infection in a German community with a super-spreading event. medRxiv Spread of virus during soccer matches. medRxiv preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted Estimation of airborne viral emission: Quanta emission rate of SARS-CoV-2 for infection risk assessment Successful return to professional men's football (soccer) competition after the COVID-19 shutdown: a cohort study in the German Bundesliga Qatar Stars League. Protocol (COVID-19) for Qatar Stars League Qatar Football Association Predicting infectious SARS-CoV-2 from diagnostic samples Virological assessment of hospitalized patients with COVID-2019 Viral RNA load as determined by cell culture as a management tool for discharge of SARS-CoV-2 patients from infectious disease wards Centers for Disease Control and Prevention Qatar Planning and Statistics authority Qatar Planning and Statistics authority preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted Can Tracking Data Help in Assessing Interpersonal Contact Exposure in Team Sports during the COVID-19 Pandemic? An Outbreak of COVID-19 Associated with a Recreational Hockey Game -Florida Cluster of Coronavirus Disease Associated with Fitness Dance Classes, South Korea. Emerg Infect Dis Possible indirect transmission of COVID-19 at a squash court Epidemiological investigation of the first 5685 cases of SARS-CoV-2 infection in Qatar All rights reserved. No reuse allowed without permission preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted The authors thank the Qatar Stars League for the support of this project. The 26-item symptom score form was provided by professor Martin Schwellnus, the principal investigator of the AWARE study.* KC and RB have contributed equally to this work. None. YOS attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted. All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.The copyright holder for this this version posted November 18, 2020. ; https://doi.org/10.1101/2020.11.17.20233023 doi: medRxiv preprint