Keeping a Pandemic at Bay: Lessons From the Tokyo and Beijing Olympics

At the time, it seemed absurd.

The decision to hold the already postponed Tokyo Summer Olympic Games during the height of the Covid-19 pandemic in 2021 seemed like a recipe for disaster. Many people feared that staging such a large event － one that would congregate thousands of people together － would only exacerbate the existing Covid-19 pandemic, especially with the Delta variant running amok through the world’s populations and vaccinations not yet fully available across the globe.

Yet, by the time the Olympic torch above the city of Tokyo was extinguished at the end of the event, the Games were heralded as an amazing success story. The expected dramatic surge in Covid-19 infections did not play out. In fact, the rate of Covid-19 infections was 0.02%, a rate considered extremely low by health experts.

“Our testing program allowed thousands of people to participate in the Tokyo Olympics and not get Covid,” said Ramanan Laxminarayan, an economist and epidemiologist and senior research scholar with the High Meadows Environmental Institute (HMEI) at Princeton University. He was one of the architects of the successful Covid testing program that was used during the Tokyo Olympics. “It was equally important to have people fly home and not carry Covid to their home countries.”

Now, Laxminarayan and his colleagues have recently published a paper in The Lancet that outlines the scale of the planning that went into preparing for the event and the testing methods employed during the event. The paper also discusses the effectiveness of these countermeasures in preventing the spread of the disease.

The low rate of infections was attributable not only to the extraordinary measures Japanese Olympic officials took to minimize the risk of transmission, but also, importantly, to the carefully considered medical safety plans that were put in place prior to the Games. Together, these were effective in both preventing the spread of the disease within the Games’ environment and also in ensuring the Games did not become a spreading event for the rest of the world. Chinese officials subsequently followed these plans during the Beijing Winter Olympics in 2022 and that event, like the Tokyo Games, succeeded in achieving very low rates of Covid infections. This success proved that, even during the height of a raging pandemic, it is possible to organize a mass gathering when appropriate medical plans are enacted.

When the Covid-19 pandemic burst on the world stage in early 2020, all of the world’s mass gatherings － from sporting events and religious services to music concerts and political rallies － were adversely affected. Many were canceled, postponed, or scaled downward in size. Significantly, the summer Olympic Games, which were scheduled for Tokyo, Japan, were postponed. This was the first time in the history of the Games that such a drastic step was taken. This hiatus allowed scientists and epidemiologists time to learn about the disease and how it spread. Importantly, the hiatus allowed researchers the time to put together a viable medical testing plan that could be used during the Games to reduce the spread of the disease.

To this end, a multinational team of experts from Japan, the United Kingdom, Switzerland and the United States was assembled. This consisted of experts from a range of different fields, including public health, travel and hospitality, theme parks, crowd management, economy and behavioral sciences.

The first step in coming up with a viable medical safety plan was to create computer simulations, which the researchers could use to project the spread of COVID-19 among the Olympic Village inhabitants. In creating these simulations, a process that took between two and three months, the researchers thought of the problem as one that could best be solved by relying on an understanding of human interaction dynamics.

“How diseases spread is contingent upon how people interact or mix,” said Chirag Kumar, a contributor to the paper and a former Smith-Newton scholar at HMEI. He was a senior majoring in chemistry when the paper was written and graduated in 2023. “In a normal community, for example, little children largely interact with other little children and their parents. And adults interact with adults.”

The Olympics, however, are a unique situation in which the “normal” dynamics of human interaction do not necessarily apply. Many unrelated people are thrown together for sixteen days; nonetheless, there are a few recognizable patterns. Within the confines of the Olympic Village, for example, athletes who are roughly the same age are more likely to interact with other athletes and people from their own delegation as opposed to other delegations.

“So, what we did was think about the problem in terms of an in-group/out-group social problem,” said Kumar. “There are lots of studies in the literature and lots of data about how people interact with others to whom they have various degrees of connection.”

The researchers used all these data in conjunction with what was then known about the epidemiology of the disease － such as Covid-19 transmission rates, recovery times and viral load － to put together these simulation models. To this they added a third layer: the impacts of varying degrees of regular Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) testing, lateral flow rapid antigen testing and vaccination. In all, the researchers simulated over one hundred testing programs. They prioritized those programs that had the fewest number of Covid-19 cases among athletes and indicated a minimal probability of causing transmission in the local populations.

When the International Olympic Committee (IOC) decided to reconvene the Games in the summer of 2021, the disease was still raging and there was widespread concern that such a large gathering of people would lead to an out-of-control super-spreader event that could overwhelm the Japanese health system and potentially affect the rest of the world. This fear was compounded when, in the weeks leading up to the Games, a new wave of infections swept Japan as health officials identified the highly contagious Delta variant of Covid-19. This led Olympic organizers to close the Tokyo Games to all spectators, creating a tightly quarantined Games. Only athletes, their staff and coaches, the media and Games personnel were allowed to attend. In this hermetically sealed environment, the Japanese authorities planned for a minimal amount of testing － only about 3,000 tests a day.

But Laxminarayan and his colleagues, fortified by all the information they had gleaned from their numerous simulations, thought differently. “We determined that 3,000 tests a day would be wholly inadequate and would certainly lead to a big outbreak,” he said. “We suggested a testing program that was closer to about 25,000 tests per day, though the organizers ended up doing even more than that.”

The best safety plan, the researchers concluded, ultimately involved a combination of two kinds of tests: rapid antigen tests and RT-PCR tests. “By layering one of these tests on another, we basically made sure that we solved the problem of having what are called Type I (false positive) and Type II (false negative) errors,” said Laxminarayan.

“You don’t want anyone who has Covid to go out and compete in the Games,” added Laxminarayan. “By the same token, you also don’t want someone who doesn’t have Covid to have to sit out the Games.”

The actual strategy of on-the-ground testing during the Games involved pre-departure testing, daily testing, during which each participant was tested once a day using the two tests, and testing prior to leaving the Games. “The goal was that the faster you catch an infection, the quicker you can quarantine the infected person so that they don’t infect other people,” said Kumar.

Daily testing was especially critical to halting the spread of the disease. The simulation model showed that testing athletes daily compared to once every four days would reduce total cases during the Olympics by up to 44%, and that this was up to a 78% reduction from no intervention.

However, because Covid-19 can spread to others before the disease can be detected on tests, the researchers also made sure that their safety plan included testing those persons who had been in close contact with a person who tested positive. “This way, you can break the chain of infections as soon as it happens,” said Kumar.

When the Tokyo Games ended, the stringent countermeasures succeeded in ensuring that a devastating super-spreader event did not materialize. Instead, only 37 positive cases among the 11,300 athletes and 464 cases among non-athletes were recorded.

Chinese officials employed these methods during the subsequent Beijing Olympics six months later. By this time, some of the ‘unknowns’ in the Tokyo data, such as cohort studies of vaccine efficacy, were much better understood. Consequently, the researchers were able to revise and refine some of their assumptions in an effort to improve the modeling. With an explicit policy of “zero Covid” against the backdrop of the highly infectious Omicron variant, a total of 1.9 million tests were done during the Beijing Games, with an average of 70,000 per day. And the result was the same as the Tokyo Olympics: relatively low Covid infections － the positivity rate was 0.01% － and a successful Olympic Games. There were only a recorded 437 infections, with 98 confirmed positive tests from athletes.

Taken together, the Tokyo and Beijing Games proved that, even with a virulent pandemic raging, clear-eyed planning based on computer simulation using real numbers in conjunction with a methodical testing program could keep a dangerous pandemic at bay.

“I think our modeling and this type of work could be used in the future,” said Kumar. “What is also exciting is that, even if you put the modeling aside, this research gave us a lot of tangible and important insights for public health and mass gatherings going forward.”

“The bottom line is this: If you test people intelligently and enough, you can have mass gatherings occur and have them safely － and isn’t that exciting,” added Kumar.

The study, “The Tokyo 2020 and Beijing 2022 Olympic Games held during the COVID-19 Pandemic – Planning, Outcomes and Lessons Learned,” by Brian McCloskey, Tomoya Saito, Satoshi Shimada, Chiaki Ikenoue, Tina Endericks, Lucia Mullen, Pau Mota, Chirag K Kumar, Ramanan Laxminarayan, Richard Budgett, David Heymann, and Alimuddin Zumla was published online in the journal The Lancet on Jan, 17, 2024.