Japan Legal Background

Introduction: Legal framework for COVID-19 response in Japan

Much of legal framework in Japan in responding to an infectious disease is governed by Act on the Prevention of Infectious Diseases and Medical Care for Patients with Infectious Diseases (a.k.a. the Infectious Diseases Control Law). In Japan, infectious disease preparation was developed synonymously as “pandemic influenza  preparedness”. Prior to the 2009 H1N1 influenza outbreak, it was often assumed that avian influenza outbreak occurred among humans due to antigenic shift. As such, the basis for pandemic preparedness was largely based on a scenario in which a novel influenza was the culprit. Discussions around influenza response began in 1997 in Japan and became more substantial beginning in 2004, when Action plans and guidelines were developed, and revisions to laws were made.

In 2009, as the government was working on strengthening the legal framework for infectious disease response, H1N1 pandemic emerged. After the pandemic subsided, Japan developed the Act on Special Measures for Pandemic Influenza and New Infectious Diseases Preparedness and Response (hereinafter referred to as the Act) reflecting lessons learned through H1N1. The aim of this law was to provide the legal basis of various measures that need to be undertaken during an outbreak and to supplement the legal basis for measures that could not be implemented under the existing laws around infectious diseases, quarantines, and vaccines.

To address (re)emerging diseases that are not designated  in the Infectious Disease Control Law

Various aspects of risk management are considered under the Infectious Diseases Control Law. For example, mandating reporting of notifiable disease cases  as well as implementing field investigation  to understand the source of an outbreak and controlling is clearly outlined in the Infectious Diseases Control Law.

In addition to managing known infectious diseases, it is critical to have a system against threats from unknown infectious diseases that is not described in the Infectious Disease Control Law. There are two necessary considerations: one is how we detect and verify signals of such unknown infectious diseases, and the other is how we implement measures against such threats legally.  When it comes to known infectious diseases, predefined system allows us to detect those diseases. On the other hand, emerging or reemerging diseases that are not defined in the surveillance system need different mechanisms to be identified and be responded. “Undiagnosed serious infectious illness” surveillance had collected cases, with fever and respiratory symptoms as well as fever with rash; however, the system created a lot of unnecessary noise in data. As the country was preparing for major events with travelers from around the world in 2020 (Olympic/Paralympic), the focus of “undiagnosed serious infectious illness” shifted more on surveillance of severe cases at designated health facilities, which was hoped to lead to earlier identification and testing of infectious diseases that could have larger consequences. The revision was made on April 2019.  This worked well for Japan as COVID-19 spread. Japan was able to identify the first case in Japan on January 15, 2020 – which was only second case found outside of China after Thailand.

Infectious diseases are generally categorized into categories I-V under Infectious Diseases Control Law. For example, patients infected with diseases in Categories I-II can be compelled to be hospitalized and patients infected with diseases in Category III can be restricted from working.  However, novel infection is not categorized yet as they are literally new. For such diseases, temporary categorizations, “designated infectious diseases”, “new infectious diseases”, and “pandemic influenza (novel influenza or re-emerging influenza)”, may be given to control (re)emerging diseases properly).

For measures to be implemented under Infectious Disease Control Law, such as recommending hospitalization to patients, it must be proven that the person in question is in fact a patient. That proof could be symptoms and positively testing for a pathogen. However, When the causative pathogens are not yet known but deemed that broader public could be at risk without an intervention, “new infectious disease” designation is used to implement restrictive measures such as hospitalization. Basically, because the pathogen is unknown, tests cannot be conducted, so symptoms and background high risk behavior must be used to identify and categorize patients in order for various measures to be implemented under the existing legal framework. Once a pathogen is identified, it can become a “designated infectious disease”. As an example, in 2003 when SARS became rampant, it was not known initially that a coronavirus was causing the disease; therefore it was initially designated as a “new infectious disease”. COVID-19 became designated as a “designated infectious disease”.

“Pandemic influenza” categorization is a special designation. There are various influenzas categorized into Categories I to V. For example, seasonal influenza is Category V. Avian influenza that happened to jump to humans (without spreading to other humans) is Category IV. H5N1 or H7N9 were both Category II as the risk of spread between humans were imminent. When an influenza is designated as “pandemic influenza”, the law allows to ask people without symptoms nor pathogens but only a contact history to stay home and report their health status. This is not even allowed in Category I. This is because such influenza is deemed to spread even if patients are still asymptomatic. As mentioned earlier, Infectious Disease Control Law is based on diagnosis and symptoms; however, in these pandemic influenza cases, it would be ideal to stop the spread of the virus by reducing people’s contact with known cases even if they are not yet symptomatic because there is a chance that they could be spreading unknowingly.

In COVID-19, these measures were applied. So while people often say that COVID-19 was “Category II equivalent”, the measures taken were more akin to those of the “pandemic influenza” designated diseases.

What does the Act on Special Measures for Pandemic Influenza and New Infectious Diseases Preparedness and Response do?

Previously, this Act encompassed “pandemic influenza” and “new infectious diseases”.  COVID-19 was added to be under the scope of this Act on March 14, 2020. There are 5 key significance in being included under the Act.

First, this Act allowed the government to ask for voluntary social distancing/physical distancing to the public and to limit large events and temporarily suspend store and facility operations. These measures are not allowed under the Infectious Disease Control Law. Infectious Disease Control Law allows for medical interventions, such as testing, isolating, and treatment, but it does not cover mass non-medical interventions.

Second, it allowed the government to treat COVID-19 as a national crisis and enabled various branches of the government to coordinate to work on the pandemic response. With the Prime Minister as the unequivocal leader of the response, all departments were brought in to plan and implement response measures while making sure that everyone was aligned and in coordination on the strategy.

Third, the Act stipulates the necessity of preparation. The Act clearly states the necessity of development of continuity plan, preparation, reserves of necessary items, training, etc. The Act was the driving force behind ensuring that those things were actually prioritized.

Fourth, the Act allowed for the temporary expansion of medical care facilities by using non-medical facilities. It allowed to create beds in non-hospital facilities to meet the surge in capacity.

Finally, it allows for vaccination based on social prioritization. When vaccines are developed, the supply is likely limited in the beginning. The Act will allow to prioritize the recipients of the vaccine so that social functions can be maintained. This is an important aspect of this Act. For example, it might be determined that the children should get vaccinated first in order to protect the future of the country.

This Act for pandemic influenza was developed under a lot of opposition. Many thought that it imagined too daunting of a scenario. For most people, these scenarios were certainly “unimaginable”. A world where outpatient clinics are overflowing, public transit ceases to operate because there are no operators, trash collection halts because there are no garbage collectors, and bodies are left without cremation because there is no one left to do that… But as we began to see reports on what was happening in Wuhan towards the end of January, things began to feel very real.

Along with the Act, the government created action plans and guidelines that were even more detailed. One of the key characteristics of these plans and guidelines was that it had a menu of implementable measures. It was not to implement all measures, but it was meant to have a list of options available in a world where we did not know about what diseases we may face. The significance of the action plan and guidelines is that the Government shows measures pertinent to outbreak responses; and this menu allows the prefectural government to develop plan and responses in a flexible way.

Although it took three months after first case was reported in China, one of the key things in COVID-19 response was that the Act was applied to COVID-19. Based on this law, a response taskforce was set up in the government, and we could implement measures with necessary tools to coordinate. We could also declare a state of emergency when needed. While there are varying opinions about both of those actions, it was important that the country and the prefectures both were prepared to implement such measures if it was deemed necessary. It was also important that there would be a legal basis for asking the citizens to comply with social/physical distancing.


As with any crisis, there were many shortcomings in the law in responding to COVID-19. While the pandemic influenza response had been developed to be flexible and had attempted to ensure that it encompassed pathogens that had yet to be discovered, a lot of the assumptions in developing the Act had been based around specific influenzas, particularly H5N1 and H7N9. Unlike COVID-19, assumed scenario saw a virus that jumped from non-human, likely a bird, that spread quickly among humans. This created some shortcomings.

Biggest assumption that differed came from the fact that COVID-19 had a very unique infection pattern compared to the influenza. Previously, it was thought that high lethality and high infectiousness could not coexist in a pathogen. This is because for highly lethal pathogens, people often die without giving pathogens an opportunity to transmit to another patient. In COVID-19, while we had high mortality rates among senior citizens, there were also many who were asymptomatic and happen to be highly infectious at the same time.

Another aspect that differed greatly from influenza was that the incubation period is longer for COVID-19. Influenza is typically 3 days, while COVID-19 is said to be about 5 to 7 days. In addition, it was also quickly apparent that most people with COVID-19 do not infect others, but a few create clusters or sometimes end up as super spreading events. COVID-19 becomes widely spread when chains of these clusters and super spreading events occur. Such characteristics gave the authority to control the COVDI-19 through public health measures (e.g. cluster-based approach); but it is also true that large amount of public health resources are needed to achieve such goal. 

Also, Influenza has known treatments and vaccines, COVID-19 does not.

With understanding some key differences between COVID-19 and influenza and the assumptions that governed the development of the Act, first major gap was that while the Cluster Response strategy was developed very quickly, Japan was not prepared to continue to conduct the rigorous proactive epidemiological surveys for a prolonged period of time. In a “pandemic influenza” scenario, it was  assumed that the first few hundred cases will be traced and later cases would not be followed. In COVID-19, this has to be a continued effort.

Second major gap was that the demand for necessary number of tests was not properly estimated. In the 2009 H1N1 flu, rapid influenza test kits worked, serendipitously. Therefore, the supply of tests did not become much of an issue in 2009 and did not come up as one of the learnings when reflecting upon the experience in the aftermath. It was such a non-issue that as the influenza response was seriously discussed over the last 5-10 years, testing demands was not a topic that was ever re-visited.

Third major gap was that necessary hospital capacity was not properly estimated. In the pandemic influenza scenario, it was assumed that once the number of patients reached a certain level, general hospitals and clinics would also begin to see patients. In COVID-19, there was a need to continue to monitor patients as well as isolate non-severe cases due to the high infectiousness of the virus. Capacity needed to do this was not taken into account. Many local governments had trained very well for detecting and accepting 1st cases, but they had not done much training on how to handle continuous flow of patients.

Lastly, the pandemic influenza scenario had not considered asking citizens to stay at home for an extended period of time. In the pandemic influenza scenario, because influenza has shorter incubation period compared to COVID-19, it was assumed that the disease would spread quickly and that spread would be obvious. This led to an assumption that about 2 weeks of people staying at home would be sufficient to bring the virus under control. In responding to COVID-19, this ended up being much longer – about 2 months. Because staying at home was never mandated and only a request to citizens, and because citizens have a responsibility to cooperate, and because having to stay at home for 2 weeks would not be dissimilar to risks people face from natural disasters that are faced by all Japanese citizens, 2 weeks of staying at home was assumed to be a risk that people should and could accept. This meant that there was nothing in the Act that talked about how to guarantee the lives of people as people could not work for more than 2 weeks.


While many criticize the Act and say that it should have included coronaviruses from the beginning or that more variety of scenarios should have been discussed, passing the existing Act was already a feat. There would have been a risk of not getting anything passed at all if it had been expanded to include unknown diseases. What can be done now is to reflect upon the experiences through COVID-19 and ensure to expand upon existing laws.

Most importantly, more seemingly “unnecessary” preparation is needed for the future. Also, more research and development capacity in science to collect evidence necessary to develop responses or to develop therapeutics, tests, and vaccines have to be built. This is known as “science preparedness”. This cannot be done once a pandemic has already struck. It has to be built over time in preparation.

Also, Japan does not have an Emergency Authorization Use system like the U.S. does. This may need to be discussed further to accommodate rapid developments of tests and therapeutics. Companies also ask to be exempt from certain responsibilities when importing medicines or vaccines in emergency situations that may not have authorization in Japan. These are things that we need to discuss to have a system in place in case something does happen in the future.

About the author

Dr. Tomoya Saito is Director at the Center for Emergency Preparedness and Response in the National Institute of Infectious Diseases. His research interests are biosecurity and public health emergency preparedness. 

Dr. Tomoya Saito
National Institute of Infectious Diseases