A Japanese infection control expert, Kentaro Iwata, removed YouTube videos Thursday in which he criticized the handling of the coronavirus outbreak on the Diamond Princess cruise ship quarantined in Yokohama, saying the situation had improved.

Below is an excerpt of his press conference. It is slightly edited for clarity, but otherwise professor Iwata's comments are verbatim.

Thank you for coming. My name is Kentaro Iwata, from Kobe University Hospital. The remarks I will make from now at today's conference are all personal and do not represent the views of Kobe University or other bodies I belong to. As you might know, I posted a YouTube (video) both in Japanese and English regarding the Diamond Princess.

Basically speaking, the principle opinion I wanted to express was a lack of adequate infection control inside the cruise ship. Two days later, this morning, and my opinion is largely the same. The problem was fundamental and that is probably based on the lack of a more fundamental or systemic issue, which is the lack of a CDC (Centers for Disease Control and Prevention) which exist in most nations, but not in Japan. So that is what I expressed. And if you want to ask me some questions or raise suggestions, I'm very happy to answer you.

Q: I think the first question has to be why you took down your original video. You appear to have taken it down. Could you explain the reasons for that?

Okay, this morning I removed my posts, both the English and Japanese versions, completely removed all of them. It's because the post became so viral and was viewed by so many people, and yesterday I was informed that significant improvement was done inside the cruise ship and that zoning, which I had a huge concern (about), had an improvement for better circumstances.

Also on the same day, the Institute of Infectious Diseases in Japan published a report showing the data of the cruise infections. This is what I suggested over the last week or so to the Ministry of Health and Labor, which is openness and transparency, and the disclosure of the data inside the cruise ship, which was never done. News coverage showed the number of the people who got tested and who got positive.

And you could have seen, you know, today's number of test was 66 and out of 66, 44 turned positive, that kind of thing, which doesn't mean anything to me because the data of the tested and the data of the results came in, it doesn't mean anything in regards to the spread of the infectious disease inside the cruise.

So what you need is the onset of the symptoms of each patient who developed the coronavirus infection and the date of that. If you see the curve which is called epicurve in the professional term, then you will distinguish between the infections occurring before Feb. 5 and after Feb. 5. And that is extremely important because unless you know the facts, how many secondary infections were occurring when and where, you can't really conduct proper infection control management.

So that was what I thought was lacking and thankfully the Institute of Infectious Diseases published that yesterday morning and it turned out that most of the Japanese passengers didn't have the secondary infection after Feb. 5, although there were infections among crews, which is likely to be a secondary transmssion. So because of these two, one with the improvement of the zoning inside the cruise ship and secondly the disclosure of the data to show the facts about the secondary transmissions, I thought my role of the YouTube post is over.

There's no need to spread the opinion and ask (people) to be aware of this issue because the issue is gone. And so I though we don't need to discuss any further regarding these and I deleted my post. So that's my answer. Did I answer your question?

Q: Before you removed your statement on YouTube, did you feel any pressure from anyone like Dr. Yoshihiro Takayama (technical advisor for the health ministry) or Gaku Hashimoto (State Minister of Health, Labor and Welfare) or other colleague of yours?

I don't know who is Dr. Hashimoto.

Q: No, it's Gaku Hashimoto.

Oh, unlike what he posted, I've never seen Mr. Hashimoto, not inside the ship and not outside the ship. Honestly I didn't even know whether the politician named Mr. Hashimoto existed until yesterday afternoon. So let me make it clear regarding this misunderstanding, probably he saw somebody other than me.

Anyway, Dr. Takayama, we had a number of communications back and forth, over the telephone, over text messages. Many of them are very technical, so I can't really go into the details about this. But I never felt any pressure from him, in terms of like, you know, you should do this and you should do that kind of thing. He asked me to remove the post two days ago, but he never had any pressure on it. As I said, I don't know Mr. Hashimoto personally, so I don't get anything from him.

Q: Yesterday you said you had concerns that the passengers who are leaving the ship might not in fact be virus free, despite testing negative. Have you changed your opinion since then?

Largely, I don't change my own opinions on many topics. One, problem with the zoning; second, problem with the secondary infections. Although, after seeing the data of the Institute of Infectious Diseases yesterday, I think the risk of passengers having secondary infections now would be reduced tremendously than what I feared before viewing that data. So I'm very glad to see that. But still, because there were crews who got most likely secondary infections after Feb. 5, that means there's still room for potential exposure of the virus from these crews, who might be spreading the virus before a diagnosis is given.

So the risk is reduced but the risk exists. So I think my opinion probably would not change. My opinion was these people who were disembarked yesterday or maybe today should be monitored for next 14 days, possibly avoiding contact with other people, maybe soft isolation kind of thing at home, and be aware of the possible onset of the disease later on. 

Q: You said your views on this have changed somewhat from yesterday, and some of your comments yesterday seemed to indicate a lack of trust in what the authorities were doing. You are receiving a tremendous amount of pressure through social media and other means. Can you explain in more detail to the extent to which you're thinking on this has changed and why?

What do you mean by change?

Q: You seem to have a more qualified response than you initially did in a very short period of time. So can we properly understand that your views on this have changed or not?

I don't think I changed my views from a large perspective. For example, I don't know whether I understand you correctly, so which specifically do you want me to comment on. I still don't get it, sorry.

Q: I'm sorry. You'd indicated earlier that some of the protective actions that are now being taken are better than they might have been from what you initially saw.

You mean the number of second infections? No? Sorry.

Q: I think we're wondering if you've changed your opinion about what you saw on board and your concerns about the lack of …

About the zoning and secondary infections? No, I don't change my opinion in terms of the risk of the secondary transmission by the practice I saw two days ago, which was totally chaotic and which was totally outrageous and which was completely bad in terms of the professional infection control measurement.

Even with the reservation that it is on a cruise ship, not in a hospital, and it is temporary measures which is for an emergency situation. I could understand a lot of circumstances which might undermine the completeness of the infection control measures. But still, you decided to keep more than 3,000 passengers on cruise inside one very closed box, or cruise, and keep for 14 days for potential transmission to occur inside, while having many infected people inside.

So the infection control measures have to be very, very thorough and very professional and very complete. And I didn't see any of these. I don't change my mind in terms of that. So I think my view still holds.

Q: You said you were told that the conditions had improved. I was wondering if you could elaborate a bit more about what has improved and perhaps even who has told you this.

I can't say who told me so. But I could tell the significant improvement was given as the improvement of the clear alert zoning. And also I became aware that the number of infected people among passengers was declining, in terms of the epicurve. So the total risk on board would have significantly changed since yesterday. Also I was informed that the persons from the Institute of Infectious Diseases returned and became dislodged as a specialist team I think, so a couple of things I thought were inadequate changed yesterday. So that is my understanding right now.

Q: You mentioned that you looked at the data and noticed that the Japanese passengers were not prone to secondary transmission and perhaps the crew were. What about all the other passengers on board?

According to my observation up until two days ago, I think the people who are on board, such as DMAT persons, officials of the Ministry of Health and Labor in quarantines, these people probably placed themselves in danger of receiving secondary transmissions because of the infection control problems. And it is still true right now. But because of the change occurring yesterday, the risk might have been significantly decreased. Still, because of the incubation period you might see the onset of the disease among those people from today and on. But at least, no new infection occurring from today would probably occur, I expect.

Q: Do you wish you had more support from the Japanese government for what you were trying to say?

Yes, I always need support from anybody.

Q: Let me ask you a quick question about the passengers who got off.  The U.S., Hong Kong, Australia other countries are all saying that these passengers need to go into quarantine for another two weeks. Do you think that should be done in Japan and if not, why not?

I think people in Japan should follow what the people in the U.S. and Hong Kong and Canada and South Korea are doing. Fourteen more days of isolation -- it depends on the level of isolation I would say -- but you need to have some sort of monitoring for the next 14 days at least. And ideally in an isolated environment because of the risk of secondary transmission.

I think it's real and if you allow secondary transmission to occur in a community that would lead to the tertiary transmissions and the spread of the disease. As you might see, there are a number of people who got infected with this COVID in Japan, but still the infections are really isolated and restricted to certain areas, such as Wakayama, Tokyo and Hokkaido. And we don't see infections in Kobe, we don't see infections in Saga, we don't see infections in Aomori.

So many places in Japan are free of infections as far as we are aware of. So it's the time of the small cluster period, where your aim is to contain the spread of the disease and ideally eradicate it. In that sense, you don't give up on allowing the new infection to occur in any circumstances.

So, some people might say, "You know, Japan is full of infections now, why do you care about the cruise ship, there's no point in making efforts in border screening and closing." But I don't agree with that view. Because we still need to fight against this disease in every effort and containing the spread of the disease.And once you allow the spread of the disease, then even if you're doing a good job up until now, you have to return to the zero period again and do the same thing again and again.

China is very aware of the risk of the re-spread of the infection from now on because they are returning to work. And that might allow the resurgence of the infection. We can't allow the same here in Japan.

Q: So your advice to passengers who have got off the ship is that the responsible thing to do is to isolate yourself for the next two weeks?

That's my suggestion. But on the other hand, we have to be very careful not to accuse these people who might develop symptoms and potentially who might spread the disease to some others because they were just following what the government recommended. So respect for their privacy, respect for their ID and kindness to these people who unfortunately could have infections later on is likewise very important, I think.

Q: Would you care to extrapolate from what you saw on the ship to express any concerns you might have about the way the disease is being contained in Japan in general?

Around the country? Not in the cruise ship?

Q: Yes, around Japan.

Around Japan, I had been saying before the cruise ship problem, I had expressed my opinion that the Japanese government had been doing a fairly good job, up until the cruise ship. They were really monitoring the disease and they prepared medical care; they prepared the laboratories, and they followed sort of contact tracing.

So far, I think Japan is doing a fairly good job for almost everything, except for the cruise ship. Potentially, the Wakayama epidemic inside the hospital, which I have another big concern about for now. So I think for this period, Japan should continue the same thing unless there's another phase of the infections occurring in some other areas.

Q: Could you elaborate on the Wakayama hospital?

We have very few data so I cannot make a big comment on Wakayama. But again, I would like to have more data on a daily basis. So how many people got traced, and how did infections occur and how many were at risk, and so on and so on. Then also I am very interested in health care personnel who got close contact with the infected people. Are they still working in a hospital or are they isolated? This concise information I'd like to have, and everybody should share, while keeping each person's privacy very secret.

Q: You yourself are in a kind of self-imposed isolation. Could you describe the precautions you were taking, your daily life, as maybe a model for what you're recommending these passengers to do as they go into, as you say, soft isolation?

First of all, I never recommend what I'm doing right now to any of the passengers. At least yesterday, I had to respond to so many interviews from morning to midnight, so now I'm scared of developing a disease other than coronavirus infection now. I'm putting myself in this self-isolation because, again, I thought I stepped in the red zone while not protecting myself i.e. PPE, that's the most dangerous thing to do as an infection prevention specialist.

I'm not scared of getting disease myself because I know that for 85 percent of cases it's just a common cold and only the small minority of people would get pneumonia and very few would die of this. But still I'm very scared of spreading this disease to others as a responsible doctor. I don't want my family to get the disease, not to mention my patients. I'm not going to take care of my patients from two weeks from the day I left the ship.

So this is my responsibility rather than for my health or safety. I also think I need to contemplate on what had been done in the last two days and seek some sort of improvement in what I could do from today.

Q: So do you plan to stay in the same hotel room for the next two weeks?

I cannot tell that for sure for now. I'm not going to tell where I'm staying, I'm not going to tell where I'm going to stay tomorrow. Let me keep this as a secret from you.

Q: Why did you take the video down, because you say you haven't changed your mind about so much of what was in the video and it seems it's an important point that needs to be out there about infection control measures on that ship as more and more passengers and disembark and as other countries make decisions about what to do to with returning passengers?

I removed my post because, first of all, my intention as seen in the end of the video was to change what was happening inside the cruise ship and my intention was not to criticize anybody personally. Therefore I never mentioned any person by name to criticize or accuse anybody. That was not my intention. But a lot of people misunderstood me, saying that I am trying to accuse somebody personally or institutionally. That's not my intention.

Leaving my posts on YouTube would allow a lot of people to continue to misunderstand me and trying to develop the some fissur between me and the other bodies which I have no intention to. I would like to be very friendly to everybody and I would like to be very rational and I would like to have a scientific discussion with anybody to improve the situation and make the situation better. That's my intention.

Very unfortunately, I didn't have any chance to have a discussion with anybody inside the ship, because I didn't have any allowance of speaking, and (was) removed from the ship. That's my regret, the biggest regret. If I could have the time to talk, then I could have suggested the improvement which I think was needed then.

After posting to YouTube, thankfully the zoning changed. And the structure of infection prevention inside the cruise ship changed and now we know that transmission dynamic of coronavirus infection inside the cruise, largely. So I think the role of the YouTube is over. To avoid further spread of misunderstanding and unnecessary division of views or hostile exchange of opinions, I just decided to remove everything.

Q: Do you think you played the role of a whistleblower in this case? WHO asked people not to overreact because the spread of the disease is mostly in China and not much in other countries. Do you think cancelling events is overreacting?

For the first question, I don't know whether I play the role of whistleblower. But traditionally, I think Japanese don't like whistleblowers of any kind. So whether I could have played (such) a role … but things changed yesterday anyway. I'm happy with the change. Whether that change will lead to the improvement of the fundamental problem, such as lack of CDC, I don't know. People could become rather adamant on what they are, so maybe the structure like CDC would be gone by now and in the future, that I'm very sorry about. But we'll see.

For the second question, I agree with WHO that people should not overreact. As I said, Japan's spread of the infectious disease is rather limited to several places. I still have a big concern whether that small cluster of diseases would reach to large expansion of the infections, which could happen.

My intention with fighting against this disease has never changed since the beginning of this program, which is never to produce a second Wuhan in Japan. If you produce the circumstances like Wuhan now, which is just a disaster, very bad disaster, it is almost uncontrollable to anybody. You should avoid that. If you allow millions of people to get infection with this virus, then thousands of people will die.

There's no way to prevent the infection to get severe. So the government said you have to prevent the severe cases but because there's no way to block the cases to change from the light to severe, you have to prevent the case to occur. If the number of the cases is small, the proportion of people who get severe cases would be small. But if you get tens of thousands of people getting sick, then a certain number of people will get severe disease.

So you have to have totally different opposite views at the same time. You have to be very careful but you have to be calm all the time. At least in Japan, there's no need for restricting any events or restricting commuting, restricting walking outside. I don't think there's any need for that as of now. Whether that would lead to the finish of this disease epidemic, I don't know yet. And we have to be prepared.

We have to be extremely cautious but we shouldn't panic, that's my opinion.

Q: You have argued Japan needs something like CDC. Could you elaborate on that? What shortcomings do you see in the current Japanese system?

For the improvement of the zoning and the infection prevention, because I had never been allowed to enter the cruise after two days ago, I haven't seen myself what is happening now. But I was informed that the significant improvement about the zoning was done. And I'm very happy to hear that because I didn't want to see far more infections among medical care personnel, ministry officials and crews and others. That is my view.

For CDC, so you need to have a concrete separate independent system among experts who can make a decision in responding to these infectious disease epidemics. And this has to be professional, they need to have the authority, they need to have autonomy, they need to have a clear independence.

There shouldn't be any cross-cuttings from anybody from the backyard because I've seen many things are decided behind the scene and we never know who decided and how it was decided and what is happening inside and who were discussing with whom and the reason and rationale for each decision making. Everything is in the dark zone in Japan. So we never know what is happening and we never know why it happened.

That's not good scientific decision-making and if you avoid scientific decision-making that would lead to wrong decision making all the time. That could be a sensational decision-making, that could be an emotional decision-making, that could be a political decision-making, and this decision-making is not very good in mitigating the real risk of infectious diseases which should be dealt (with) purely scientifically to protect people's life.

Also the scientific decision making is good in regards to preventing social problems such as prejudice, discriminations. We Japanese suffered from social issues in terms of infectious diseases in our history, such as leprosy, HIV infections and so on. And we should avoid that. Leprosy patients were isolated because of the wrong view of prejudice -- by seeing the people's face, and they wanted to isolate the people. Scientifically speaking, leprosy isn't contagious to anybody in normal life so you shouldn't isolate these people.

Therefore scientific decision-making is very important in protecting human rights and avoiding these unnecessary discriminations.

Back to CDC talk, again, scientific decision-making independent body and autonomy and authority is needed. China has it, South Korea has it, because East Asia has a tendency to decide (in) backyards but people are beginning to change. Japan has never changed yet and I think we should.

Q: I was wondering what you think the problems that you saw on the ship originated from. Was it because of bad examples of scientific decision-making in terms of crisis management? What do you think could be used as a lesson from what you saw on the ship in the other ...

I think the simple answer is the lack of CDC, as I said before. Why the situation inside the cruise ship had inadequate infection prevention, I think it's because of the lack of principles. So, infection prevention needs principles. And principles will lead to a procedure, not the other way around. What I think is, the people initially implemented zoning, implemented infection prevention procedures, implemented PPE, they did prepare infection prevention management. I think they think they still think that they're doing a good job.

To me it was not good enough because there was an exchange of dirty and clean, there was confusion about the role of PPE, there was allowance of the crews potentially infected walking around. Again, remember I said well there are not many secondary infections but actually there were secondary infections among the crew. And we shouldn't have a complacency about it, you know, you can't say well that's a crew so it's okay, kind of thing, you can't say that.

So the number of the issues was based on the lack of principles, which is to distinguish between dirty and clean clearly because a virus is invisible. So unless you have a principle in dividing these clean and dirty scientifically, you can't have a clear distinction between these two. Even if you put many things in the manual, this is green zone, this is red zone, this is PPE, that would be violated very easily unless you have the understanding of the clean area and the dirty area.

That was very clear, for example in Africa when we were fighting against ebola. But it was not on the Diamond Princess and that's the very reason I got scared of getting infection myself. So the principle will never be given by the bureaucrats because they never had infection prevention training, they don't have experience and they don't have a system. CDC should have all of these, so this is how I feel.

Q: We've just learned that two people from the cruise ship have been pronounced dead. Any kind of reaction?

Because the total number of the people who got infected in Japan is relatively small comparing to the one in China, because of the small denominator, the small change in the number of the people who are dead would hugely change the percentage. For example, if you had 100 people who got infected and you have one dead, if it becomes three that would become 3 percent.

So the small change in a death case would significantly change the percentage. So it's too early to judge in Japan whether there was a change in mortality as a nation, including China. I don't know the details about this cases because this is the first time I heard about it, so I can't really comment on this specific point.

Q: You talked about crew, you talked about your observations about the personnel on board, you talked about how some of the Japanese passengers did not look like they had secondary transmissions. What are your observations for the other passengers having read the report that you've just read?

Other passengers? In terms of transmission? I don't know. We have hundreds of asymptomatic people, in whom the onset is never known. We will never know the exact onset in these people who got the detection of infections asymptomatically. So we don't know about that. We don't know much about more than hundred people who have no data regarding the onset of the symptoms. So we have several things we still don't know.

Also we don't know whether or not they will develop a disease from today and on. So I can't say from the report, the report from the Institute of Infectious Diseases yesterday was very reassuring, as they themselves admitted, that didn't answer all the questions and concerns what we have right now.

Q: Do you think the appearance of your video pressured the Institute of Infectious Diseases to release these data?

I think so. But I don't think they would say so either.

Q: You say that you're not against quarantine but you say that the way that it was done was incorrect. Is my understanding correct? You had experience with ebola in Africa and I was wondering if you could give a bit more detail on the kind of standards you saw, and what you were therefore expecting to see on the ship apart from the green zone on red zone things. I was wondering whether you have a few plans in the future to work together with your contact at the example in the government or do you have any plans to try to help with this crisis at all?

For the quarantine, I agree with you. I'm not against quarantine but I'm not saying you should quarantine people either. The decision-making inside a cruise ship is extremely difficult. So if I were in charge of this case, probably I had to think thoroughly what to do on Feb. 5 when the person was identified to be infected.

A cruise ship is a very difficult place to protect people, it's a structural problem. So we have to decide whether to release people outside the cruise or to keep inside the cruise. The former would cause a lot of people in the city to have a second infection so that has the shortcoming.

But keeping the people inside the cruise ship could allow people inside the cruise ship to have a spread of the infection further. So either scenario has shortcomings and the decision-making can be very, very difficult. However, if you decided to keep people inside a cruise ship and isolate and put in the quarantine for 14 days, that has to be very, very thorough and has to be very complete because if you allow the secondary infection to occur, then that would become a day zero again, and that has to isolate the people for another 14 days. That could be painful for everybody.

To reassure the procedure of the 14 days quarantine, you have to keep the data updated every day and monitor it and make sure there's no secondary transmission every day.  And that was not what the people in charge were doing and I criticized it.

Thankfully, the data came out yesterday, so that was good. But looking back, it should have been done every day just by updating data since Feb. 5. So things were done, in terms of the epidemiological data management, I think it was not completed properly.

I was a family physician in Beijing, China and seeing several people who could potentially have a SARS case, and I was also an infection prevention specialist working for WHO in Sierra Leone. Again, I did a lot of work, but you have to have a clear distinction between where the virus could potentially be and where the virus doesn't exist inside the facilities. That could be a hospital, that could be a tent, that could be a ship, that could be cars, because ambulances need this kind of distinction too.

So a lot of application of this principle exists. Some people might say this is a big cruise ships so the infection prevention management inside a hospital doesn't apply to the cruise ship. That is technically true but principally it's the same. The principle is to divide between dirty and clean. You have to follow that principle and you have to modify you're techniques and apply that to everywhere you go to protect people including a healthcare personnel.

For example, in Africa, in ebola, most people were treated inside the tent, developed by UNICEF and other bodies. But tents were completely defined as red zones and people were not allowed to enter into that red zone without wearing a PPE; upon being out of that red zone, then you have to remove PPE very correctly with two people by somebody watching monitoring and he has to go out without a PPE as the green zone.

And keeping that procedure accurately would prevent further transmission to occur particularly among healthcare personnel. Green, red distinction is very useful in protecting healthcare personnel, and the others entering the red zone. It's nothing to do with the second new transmission among the passengers and crews, so this has to be clear.

Q: For someone who has been tested negative, if you do another test one week later, is there a risk that this test will be positive?

Yes, there's always wrongness of the test. That could be technically wrong and that could be essentially wrong. There is no test which is 100 percent accurate and 100 percent sensitive. So that could be falsely negative. And we have to be aware of the potential danger of that. So the test negative is not no infection. We have to know it. Therefore we have to utilize the test result wisely to interpret the results very accurately, otherwise we might release people who might have infections. So that's very important.

Q: That may have happened because, for example, people who left the boat yesterday, some had been tested on Feb. 12.

Yes, but to me, it doesn't matter because I don't care about the test result anyway to begin with. You might have a test negative while being infected, also you might have a new infection two days later, so you could have a lot of scenarios you could consider. But still, as far as you remain being wise enough to know that test negative is not no infection, your decision is easy. You have to keep watching this person for the next 14 days, regardless of the test result, regardless of the date of the test -- that doesn't matter at all.

Related coverage:

Japan disease expert pulls videos blasting situation on virus-hit ship

2 elderly passengers of virus-hit ship die in Japan

China says media blatantly insulting country must pay price