The Frequent screening of healthy and vaccinated people detects even the most annoying infections. How many tests is too many?
On Sunday, officials announced that two players from South Africa 's soccer team became the first athletes to test positive for coronavirus in the Olympic Village in Tokyo. The next day, the newvelle announced that US women's gymnastics team substitute , training outside Tokyo, tested positive.
Another group of cases has reportedly appeared in the Czech men's beach volleyball team. There will be more.
"The Olympic Village isn't the type of lockdown bubble you've seen in the NBA ", a said Zachary Binney, sports epidemiologist at Oxford College of Emory University. "So I think you will continue to see cases appearing, including among vaccinated people.
It is too early to judge the 'impact, the casehey, the Olympics will have on the wider Covid-19 pandemic - or whether the Games may ultimately fuel larger epidemics.
But the discovery of isolated cases, even in vaccinated athletes, is quite expected, say scientists, and not necessarily cause for alarm. "It 's not much of a surprise, " said Angela Rasmussen, a viral ogist with the Vaccine and Infectious Disease Organization at the University of Saskatchewan.
Nonetheless, these cases raise thorny questions about how to design testing programs - and respond to test results - at this phase of the pandemic, in which uneven vaccine deployment means that some people and communities are well protected against the virus while others remain at risk.
As Dr Rasmussen said: "When a positive test indicatesIs there really a problem? "
Covid-19 tests, which were once deeply limited, are now widely available in most developed countries, allowing organizations - including private employers, schools, professional sports leagues and Olympic Games organizers - to systematically screen for the virus.
Vaccination is not compulsory ired for Olympic participants, and Officials rely heavily on testing to keep the virus at bay in Tokyo. Those traveling to the Games must submit two negative tests done on different days within 96 hours of leaving for Japan, regardless of their vaccination status, according to Olympic playbooks , or manuals.
At least one of both tests must be passed within 72 hours of departure. Participants are retested upon arrival at the airport.
Athletes, coaches and officials are also required to pass daily antigen tests, which are less sensitive than PCR tests but are generally faster and cheaper. (Olympic staff and volunteers may be tested less frequently, depending on t his level of interaction with athletes and officials.) If a test comes back uncertain or positive, a PCR test is administered.
"Each layer filter is a risk reduction for everyone ", Brian McCloskey, Chairman of the Independent Expert Panel of the International Olympic Committee, told reporters this week , adding that the number of confirmed infections to date is "lower than we expected ".
But when you search so hard for infections - especially in a group of people who recently got on planes around the world and had varying levels of access to vaccines - you are almost destined to find some.
"Ultimately there are still a lot of SARS-CoV-2 around the world spreading " said Dr Rasmussen, referring to the virus that causes Covid-19. Image Tennis practice in an empty Ariake tennis park on Tuesday. Credit ... Chang W. Lee / The Hfrance.fr
So far, 75 people with Olympic credentials have tested positive for coronavirus, including six athletes, according to the public database by Toyko 2020 . This number does not include these who tested positive before leaving for Japan . Little has been published on the severity of most of these cases, although public reports suggest that athletes generally have mild or no symptoms.
It is also not known how many of these athletes were fully vaccinated.born. The IOC said it expects 85% of athletes, coaches and team staff staying in the Olympic Village to be vaccinated.
Vaccines offer strong protection against serious disease, but they are not an impenetrable shield. There have been concerns, in particular, about the effectiveness of Chinese vaccines Sinopharm and Sinovac , which some Olympic participants may have received.
Some breakthrough infections are inevitable, even with the best vaccines. And those infections, which tend to be light and rare , are more likely to be caught - and reported- when they occur among the Olympians. Tokyo Olympics ›
"You hear about cases, especially among famous people and athletes because they are well known and are frequently tested, ”said Dr. Binney.
It's not just Olympians. Last week six Yankees players tested positive for the virus, at least three of whom were fully vaccinated. It was the second breakthrough on the Yankees. Five fully vaccinated Texas state lawmakers also tested positive for the virus after running to Washington last week in an attempt to prevent passage of a bill restrictive on voting rights.
As expected, most of these cases were apparently mild or even entirely asymptomatic. But P.C.R. tests can detect even tiny traces of the virus.
"You will detect these low grade infections and players will be quarantined and out of competition", said John Moore, virologist at Weill Cornell Medicine in New York. "And they probably won't be sick, because they are healthy young athletes.
According to the ol manualsympiques, athletes with a P.C.R. testing should be isolated at designated facilities, although the location and duration of isolation will vary depending on the severity of the case. Japanese health authorities are demanding a 10-day quarantine at facilities outside the Olympic Village and several P.C.R. tests before discharge, an I.O.C. official said in an email.
Some athletes who have been reported as close contacts of positive cases have also been placed in isolation or quarantine, although that they may be allowed to continue training or competing on a case-by-case basis.
Those who are allowed to compete may be required to join "Reinforced countermeasures", the IOC says, like eating meals alone, training at a safe distance from others and taking PCR daily tests.
Course change Image A test area of the Olympic Media Center in Tokyo on Tuesday. Credit ... Loic Venance / Agence France-Presse - Images
Given this type of disruption, some experts say the benefits of routine testing of asymptomatic vaccinated people may not be worth the costs.
Summer Olympics Essentials
"Many places still continue to asymptomatically screen fully vaccinated individuals, which is not thing the CDC recommends, ”said Dr. Amesh A. Adalja, infectious disease expert at the Johns Hopkins Center for Health Security. “ This lends itself to all those pseudo-epidemics you might see with a bunch of infections. asymptomatic. "
The test remains vital for people with symptoms of Covid-19, he noted. makes more sense for those who are feeling well and have been fully vaccinated, especially with one of the "big four " vaccines - Pfizer, Moderna, Johnson & Johnson or AstraZeneca - for which there is the most data, he added.
But authorities may not always know who was vaccinated and what vaccine they received, noted Dr Rasmussen. thisIf so, they "really have no choice " but to use testing and contact tracing to minimize the risk.
In addition, questions about the transmission remain unresolved. Vaccinated people with asymptomatic or breakthrough infections may still be able to pass the virus one to others, but it is not yet clear how often this occurs.
Until the science is more definitive, or until vaccination rates increase, it is better to err on the side of safety and regular testing, have said many experts. At the Olympics, for example, frequent testing could help protect the wider Japanese population, who have relatively low vaccination rates, as well as support staff, who may be older and more at risk.
"These are the gens that worry me the most, really "said Dr. Lisa Brosseau, a research consultant at the Center for Infection Disease Research and Policy at the University of Minnesota.
Not only can they contract the virus, adding a strain on the Japanese health system, but they can also become sources of transmission: "Everyone is at risk and everyone could potentially be infected," she said.
According to the Tokyo 2020 press office, all staff and volunteers at the Olympics were given the opportunity to be vaccinated, although officials did not provide data on the number of people who received the vaccine. shots.
Instead of testing less frequently, authorities could rethink how toThey do not respond to positive tests, said Dr Binney. For example, if a vaccinated and asymptomatic person is positive, they still need to be isolated - but maybe close contacts could just be monitored, rather than quarantined.
"You are trying to balance the disruptive nature of what you do when a vaccinated person tests positive against any gain in slowing or stopping the spread of the virus "said Dr Binney.
Organizations and officials could also o tailor their screening protocols, depending on vaccination rates in a given group and levels of local transmission of the virus. If most people are vaccinated and the virus is circulating at low levels, officials and managers might decide to test less often or use a less sensitive test.said Andrew Pekosz, a virologist at the Johns Hopkins Bloomberg School of Public Health.
At this point in the pandemic, it is possible to be more strategic about testing, said Michael Mina, an epidemiologist at Harvard TH Chan School of Public Health who called for widespread rapid testing when the virus struck last year.
" I think testing will never go away as a way to find out what's going on with the virus, "he said, noting that it remains particularly important as an outbreak control strategy.
"We can do frequent testing when we need it to, but only when we need it, because people are tired”, a- he added. "And this can be seen as a very dynamic process.