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WHO expert: Lessons learned from COVID-19

December 29, 2020

Maria Van Kerkhove, the WHO’s technical lead on COVID-19, reflects on the discovery of the asymptomatic spread of COVID-19 and the WHO’s response.

Citizens queue for COVID-19 tests in Qingdao, east China's Shandong Province.
Mass testing is designed to identify asymptomatic cases.Image: Li Ziheng/Xinhua/picture-alliance

Deutsche Welle: What do you see as some of the WHO's greatest strengths and achievements during this pandemic?

Dr. Maria Van Kerkhove: One of the strengths that the WHO has is its international networks and our partners and our collaborators. During this pandemic, we've worked with literally thousands and thousands of scientists all over the world — medical professionals, and academics from so many different technical disciplines that work with us on very specific topics related to personal protective equipment, therapeutics, the development of vaccines, the development of diagnostic tests. 

I think one of our strengths, which is not just within this pandemic, but developed over decades, is to bring this group together so rapidly that we can share information — firsthand information, frontline information, patient level information around treatments and care — that's faster than any peer review publication that can be written. 

Maria van Kerkhove speaking at the WHO office in Geneva.
Maria Van Kerkhove is coordinating the technical response of the WHO to the SARS-CoV-2 pandemic.Image: picture-alliance/dpa/Keystone/F. Coffrini

This is really critical in the beginning of a pandemic, epidemic or outbreak when you don't have much information on that particular pathogen, especially if it's new. 

Looking back, what things could have been done better? What things do you plan to do better in the next pandemic, whenever and whatever that is? 

The easy answer to that is everything can be better, and it should be better. And I think that's something that we all strive for. I think one of the challenges for me in answering that question is trying to think in terms of the decisions that we made based on the information that we had at that time.

I think some of the things that we need to do much better is around supplies and supply chains. We still have a problem with the production of Personal Protection Equipment (PPE), for example, masks, gloves, gowns, goggles, respirators, equipment, ventilators, oxygen supplies. 

There was a total market failure, a supply chain failure. And we worked really hard with partners to try to make sure that production capacity increased and that we got the supplies to frontline workers, but it's still not fixed. 

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I think another area which has been really challenging in this pandemic is communication: communicating uncertainty, communicating what we know at the time, what we don't know at the time and what we're learning or what we're doing to address those unknowns. So, I think that's an area that we need to look into. 

Speaking of communication, I want to talk about this New York Times article,  and there have been others from both The New York Times and other outlets regarding how long into the pandemic you and others at the WHO were saying transmission of COVID-19 from asymptomatic people was rare. I want to hear your side of that story and how you approached the science.

Since February, the WHO had been talking about the possibility of asymptomatic spread. 

And in fact, we updated our guidance in late February, early March to include the definition of contacts before people developed symptoms. 

But the point was that it was possible and the point was that it was something that we needed to prepare for. So we immediately took that seriously. 

That seems to be forgotten because everyone refers to one answer to one question I gave on June 8, where I was describing the differences between people who were truly asymptomatic, people who were in the pre-symptomatic phase, and people who were symptomatic and the last three words of my answer of 'it's very rare' had been used by some politicians in some countries to say, 'WHO says that asymptomatic transmission does not happen,' which the WHO has never said. And to use it as a way to say that we didn't think that it was important, and it's just not true. 

Having said that, it was confusing to some. And so that's why the next day we did a Facebook live to clarify. It wasn't a reversal. I wasn't forced to do anything. It was just something was taken out of context and it was confusing, so let's clarify. Let's set the record straight. 

I think it was in April, we defined asymptomatic transmission as people who didn't develop symptoms and never developed symptoms. Then we defined pre-symptomatic transmission as individuals who transmitted just before they developed symptoms and symptomatic transmission as people who had had symptoms and transmitted. And we did that to try to be helpful, because as we received more information from lab studies, what we were learning is that people appeared to be most infectious around two days before symptom onset, really right at the time of symptom onset — that seemed to be the highest viral loads.

Two reviews have recently come out that suggest that the proportion of the population that is truly asymptomatic, that is, they are infected but never develop symptoms, is somewhere between 17-20%.

Now, the models suggest that asymptomatic and pre-symptomatic transmission is 40-45% of transmission.

I'm wondering if this focus on the debate between the asymptomatic and pre-symptomatic was not that helpful earlier in the pandemic, especially in terms of the public understanding what these terms mean and that the real message is that people who don't feel sick can transmit the virus?

Yes, I think that's an excellent point, because from a public point of view, either you have symptoms or you don't. There's no difference between pre-symptomatic and asymptomatic. And the fact that people could feel well. What concerned me even more was the people that felt just a little bit unwell and didn't know all of the signs and symptoms for COVID. That, to me, was one of the most concerning things. Because for SARS and for MERS, people are most infectious later on in the disease, so around day 10 after symptoms onset. But for this virus, the highest viral load is right at the time they develop symptoms, including very mild symptoms.

Do you think that was an issue in terms of people assuming that this virus would act the way MERS or SARS did rather than studying what was actually happening and taking a fresh look?

Well, I think for the countries that have done well in this pandemic, it didn't matter because they, from the beginning, knew immediately what they needed to do. And they focused all of their efforts on really aggressive case finding and contact tracing, isolation of cases, quarantines of contacts. If you do that and you do that well, you can prevent cases becoming clusters, clusters becoming community transmission. And we saw that over and over and over again. 

Even in Korea, in the Daegu area, they did a massive outbreak investigation associated with that church and surrounding areas. They increased their testing to do screenings. They had thousands of contacts under observation and in quarantine. They provided medical care in medical facilities or specialized facilities. And they didn't go into lockdown, but they brought that outbreak under control. And for them, what was important was the dedication and the consistency of a comprehensive contact tracing approach that worked.

I know it factors into how countries respond, but everything that China, Japan, Cambodia, Thailand, Vietnam, Australia, New Zealand, on and on and on did, worked.

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Obviously there were some pretty significant things to consider once it was realized that this is an aspect of the disease, that asymptomatic or pre-symptomatic people can transmit it, contact tracing and some of the difficulty with that, difficulty with administering widespread testing, especially at the beginning when that wasn't as available. How did you think about and approach these challenges?

We take a precautionary approach in terms of the information that we have.

In terms of mask use, this one has also been quite challenging because we have always recommended masks as part of a package of interventions primarily for health workers, but also since January for people who are unwell and people who care for those unwell.

Now, this information on asymptomatic, pre-symptomatic transmission was really important for us to understand, because if you're only asking people that have symptoms, then you're missing the possibility of source control for those who don't have symptoms.

In April, what we did for mask use is we didn't come out with guidance that said, everybody wear a mask. And we didn't do that for a number of reasons. One is because we didn't have data and evidence to support that policy on a global level. Secondly, we were still having a shortage, a global shortage supply of masks and we were just beginning to commission research on fabric mask use in terms of what types of fabrics and breathability and filtration and all of that.

It didn't work because what the world wanted to hear from the WHO was either wear it or don't.

Taking a precautionary approach, though, wouldn't it have made sense to give that guidance to say: "Wear masks. We're still trying to understand more about this, but it's a pretty easy thing to do, especially if you can make cloth ones at home"?

We actually said: Wear masks where you can't do the physical distancing. We were much more specific on that in June: Distance, physical distancing of at least a meter or more (the further the better) is probably the single most important thing that people can do right now. Adding masks to that is really critical. And you have to do that.

What we've seen is that some countries have had almost an overreliance on masks and not on the physical distancing, so you have to make sure that you do all that. 

Sure, we could have said everyone wear a mask, but we didn't have the evidence base to support that. 

Do you think lives could have been saved if the WHO had communicated earlier and more clearly just how easily this virus could spread?

That's an interesting question. I think all of us globally could have done a lot more to make sure that we did everything we could to save as many lives as we could. 

We said from day one that this is a dangerous virus. We said from day one that this virus spreads easily. We said from day one that this was a respiratory pathogen and that it spreads between people. We outlined all of the different measures that needed to be put in place.

And the countries that did so really have done a good job of either preventing these horrible outbreaks from happening in their countries or really bringing them under control as quickly as they could. 

It's one thing to set policies and to tell people what to do. The other is to provide an enabling environment for people to do so. So, we initially had talked about staying home if you're unwell, limiting your interactions with others, keeping your distance, washing your hands, avoiding crowded spaces. But it's easy to say so. But it is very difficult for some people to implement if their lives and the lives or their families depend on making a daily wage.

When it comes to public health, do you think these countries and governments have learned about how to make political decisions regarding public health and making sure that they're prepared for pandemics like this?

Yes, I think the countries that did well in the beginning really had experience with other pathogens, similar pathogens like SARS, like MERS, like avian influenza, H5N1, H7N9, with Ebola, with yellow fever, with meningitis. And so that experience with infectious disease outbreaks that impact communities and families and economies gave them the muscle memory and the trauma almost, to take action. 

For me, one of the most important examples of that is in Korea. In 2015, there was an outbreak with 186 cases and [38] deaths.  And that outbreak of MERS involved more than 70,000 contacts that were followed. And it had an economic impact of US$8 billion.

That event in Korea showed them what needed to be changed and as a result of that, they changed their entire infrastructure around public health and public health law and data management and workforce. We've seen that across countries in the Mekong Delta region because of H5N1. We've seen that in countries across Africa because of their repeated experiences with infectious diseases. 

What I'm hoping is that, from the trauma that the world has seen, countries use this as a way to propel them towards taking the right actions for preparedness. In wealthier countries, there's an overreliance on care. But what we need is really strong preventative measures. We need a public health workforce that can be in place to carry out the actions for case finding, testing, quick results, contact tracing, management. 

I am hopeful that countries are learning from this and will take the actions that will put us in a better place when this happens again, because I think, unfortunately, it will happen again.

What has it been like working in public health during this past year? And what lessons have you learned?

It's been a challenging year. It's been, on the one hand, exhilarating in terms of the science around this and the camaraderie and collaboration with people all over the world to really understand the virus with a goal of stopping it. It feels like one long day, one long night. I mean, I really can't believe it's December.

I know you're asking me questions that are challenging us and we expect that and we want that. But there should be no question whatsoever in the objectives of WHO and the objectives of our guidance to protect people, to prevent infections and to save lives.

We're not perfect. No one is perfect. But we are out there every day talking and answering questions directly. We are putting this information in our guidance, which is catered for decision makers and frontline workers, and we update that as necessary. Everything is in a constant state of review and revision. 

It's a lot to manage in terms of the sheer volume of work, but everyone that I work with is just determined to end this and is determined to do that as quickly as possible, because all of us, just like you, want to go back to what we thought was normal. I think there is a new normal in the sense of how we are going to live our lives going forward. 

The lives that have been lost is tragic. It's nothing short of tragic. It's been a difficult year. And I'm very much looking forward to 2021 with the rollout of the vaccines and vaccination.

But in the meantime — the next six months, the next year — it's going to be frustrating for people because we want it to be over so quickly, but it's going to take some time. 

Dr. Maria Van Kerkhove is the World Health Organization's technical lead on COVID-19 and an infectious disease epidemiologist. She is responsible for the development of guidance and advice for all member states of the WHO.

Sam Baker conducted this interview for a special episode of Science Unscripted. The interview has been condensed and edited for clarity.

Deutschland Samantha Baker Porträt DW
Sam Baker Journalist, Audio Presenter & Senior Producer@srmBAKER