COVID-19—VP&S Alumnus on the Frontlines in Singapore

March 25, 2020
Dr. Poh Lian Lim
Poh Lian Lim. Image courtesy of Dr. Lim.

Poh Lian Lim, MD’91, is director of the High Level Isolation Unit of the National Centre for Infectious Diseases and a senior consultant in the Communicable Disease Division of the Ministry of Health in Singapore. During this COVID-19 outbreak, she is involved in direct patient care as well as the development of clinical, research, and public health protocols. 

The VP&S Alumni Association recently spoke with Lim about Singapore's response to the new coronavirus and her advice for physicians.


Singapore has received praise for its public health preparedness during this epidemic. Let’s go back to 2003 and the SARS outbreak, which killed 33 people in the city-state of Singapore over three months. How did that experience impact your and Singapore’s readiness for COVID-19?

In 2003, I had just moved from Seattle to Singapore as a young infectious disease attending physician. I was diagnosing SARS cases and managing critically ill cases in the ICU at Tan Tock Seng Hospital, which was Ground Zero for the outbreak. Because we were caught in the first wave, we had no diagnostic testing for the first six to eight weeks. We had to make decisions about whether someone had SARS based on the clinical presentation and the epidemiologic risk factors. When you discover a new pathogen or virus in an outbreak, it is a bit like an astronomer discovering a new black hole, star, or planet; there is so much to discover about the new virus, but you don’t have the luxury of time—or complete facts.

In that outbreak, we didn’t have enough isolation beds or negative pressure rooms, so you had to decide whether someone had SARS and then move them into the cohort ward. That was a huge burden of responsibility as a physician because the presentation was like atypical pneumonia. If you were wrong, then you would give someone SARS on top of their mycoplasma pneumonia. In an outbreak, you have to make decisions with incomplete information in the middle of a rapidly evolving situation. You have to make that decision with what I call a certain margin of public health safety. We realized that if you have an outbreak of a respiratory infection, then your duty in some ways is to isolate first, talk later. Because if you don’t isolate that patient, then instead of one patient you potentially have 10, and more people get hurt and die.

We were able to stop that outbreak with meticulous infection control, isolation, and quarantine. That SARS experience made Singapore realize the importance of outbreak preparedness, and so in the last 17 years Singapore has continued to work on lab research capacity, hospital contact tracing, drills for outbreak preparedness, and infection control practices.  


The United States is struggling to develop and deliver enough tests for COVID-19. Can you explain how Singapore has approached the development and delivery of testing?

As soon as China published the viral genetic sequence, research labs like the Agency for Science, Technology, and Research (A*STAR) and our national public health laboratory, NPHL, started work on developing SARS-CoV-2 RT-PCR and diagnostic tests, because we realized from SARS how difficult it was to implement isolation and quarantine if you didn’t have diagnostic testing. People would storm and say, “Hey, why are you holding me here?” It’s a lot easier if you can say, “Your test is positive.” So, the testing is absolutely crucial. And we had to validate the test in different samples. Even though we know the primary symptoms are respiratory, it’s a systemic infection and you have to figure out how the PCR performs in different samples, such as blood, sputum, nasal swabs, and even urine or stool.

We realized early that strengthening every hospital’s quality assurance for diagnostic testing would help surge capacity. Because if you only have central testing, then there is a bottleneck in the system. Singapore is basically a city-state. We’ve got eight or nine acute care hospitals. If you don’t want to put too much pressure on the central lab, then you have to make sure that, at every hospital, diagnostic lab tests for COVID-19 are good enough to stand on their own. We realized that an important part of the outbreak response is lab confirmation and lab surge capacity.


There is constant talk in the United States about “flattening the curve” of infections so that health care capacity remains sufficient to meet demand. How and when did Singapore implement this strategy? 

We tend to call our strategy “containment,” but it’s essentially the same idea. Flattening the curve is the net effect when you reduce the effective reproductive number by isolating infectious individuals and quarantining exposed persons. 

To implement this strategy in Singapore, what we focus on is identifying people who have the infection, because they are infectious to others. Once we identify an infectious case, we isolate them in hospital and test them sequentially until we know they are no longer shedding virus. It’s basically isolating infectious cases, contact-tracing those who have been exposed to that person after they became infectious, and then putting those exposed people into quarantine and telling them to monitor their health and testing them when they develop symptoms themselves. A lot of times you may not realize that that person coughing near you two days ago actually had COVID-19, because cough and colds are very common in a community. But once you know that that person had COVID-19, because you were called by the health authority, then when you develop a cough you understand that cough differently: This is something I need to take care of, instead of going to work and trying to tough it out. So that is an important way of stopping transmission, and the net effect of that is flattening the curve. 


 Was that also true with SARS, or is this a new challenge?

I think in SARS there was very little asymptomatic transmission and people were a lot sicker with SARS. They had high fevers that could go on for 10 days straight. Usually, the cough developed two or three days after the fever started, so fever was actually a very helpful clue. 

This COVID infection is a little bit different, because more people have mild symptoms. We don’t think there is a whole lot of COVID transmission from people who are completely without symptoms. Our center has published a paper in the New England Journal of Medicine of people held in quarantine who were close contacts or confirmed cases. There were indeed several people that had a positive swab who didn’t have symptoms, but by and large, we don’t think that they transmit that much. If you think about the way transmission happens, because this is a respiratory virus, people transmit if they are coughing and sneezing. And coughing and sneezing either infects people directly by droplet spread—very rarely airborne spread—and contaminated surfaces. So, if you are not coughing or sneezing, then you are much less likely to spread it.

What we do know is that there are people with very mild symptoms—you know, just a scratchy throat, a little bit of achiness. Sometimes people think “Oh, that’s just a hangover.” And then they go about their daily work and spread the infection. So, we do think that a lot of the transmission may be from people with milder disease, and COVID has a larger proportion, maybe up to 75% of people, with mild disease and no pneumonia. That makes controlling COVID more challenging.


One of the remaining activities that Americans have available to decompress is walking outside. But people are still feeling paranoid. Will someone running by, huffing and puffing, get me sick?

Generally, when people have had close contacts, it has been closer than six feet and longer than 30 minutes. So, transient contact where someone is running by you in Central Park, that is minimal contact and probably not a risk. 


How is daily life being affected in Singapore? 

In Singapore, we haven’t had a shelter-in-place lockdown. What we have had is a very calibrated response, because the situation keeps changing. In the first wave of the outbreak, when most of the cases were coming in from China, Singapore instituted entry restrictions for tourists visiting from China, and China itself instituted an outbound ban on tour groups. So that was very responsible of China. Then we asked that people who came back from China or hot spots like Italy, Iran, and South Korea self-isolate for the 14-day incubation period: You didn’t go to work, your employer was asked to give you paid leave, you couldn’t go to school. In general, we have said that people should do safe distancing: If you were unwell, you had to be socially responsible, see a doctor, and get a medical leave for up to five days if it was just a mild cough and cold. But if it persisted, that you should go back and go see the doctor who might refer you to a hospital to get tested for COVID-19. And if you did have COVID-19, then obviously you were in the hospital until clear of infection.

So far schools and universities have not been closed, but if there was a case where people were exposed to an infectious person, then they would go into quarantine. The classroom would be cleaned and disinfected before being used. Singapore is prepared to close schools if necessary. Since SARS we have been exercising the schools, so that every year they have an internet day or two when all students stay at home to access their classes, and we make sure students have access to computers. People know what distance learning would look like.


Is it possible to imagine life returning to normal in 2020? 

As we watch this pandemic evolving, our best estimates are that COVID-19 is going to last at least 12 months. And it’s going to reach different countries and affect different countries in different ways depending on how resilient their health systems are, their access to diagnostic testing, what they do in terms of social distancing and managing the outbreak. We will probably go through several waves of this. The first wave was from China. In Singapore, we dealt with that. And the second wave is now from Europe. That requires different measures. If three months from now it hits another continent or group of people, you can see this going on, wave after wave over several months or a year. So, I think it might well be 2021 before life returns to some semblance of normalcy. But in many ways, you will find a new normal even in the midst of the outbreak when it goes on for months to a year or more. 


People are hearing about herd immunity as a possible strategy to safeguard nations against COVID-19. What’s your view?

The term herd immunity actually refers to vaccine immunity. If you vaccinate 90% of the population, then you reduce the number of infections bouncing around. The 10% that didn’t get vaccinated—maybe they didn’t have access or they refused—are still protected by herd immunity. That works for vaccines.

In this particular instance, because COVID-19 is a novel pathogen, the entire world is susceptible. We have never seen this virus before, as far as we know, and there is no immunity. To get herd immunity, you would basically have to have most of the population infected. By the time it burns through 80% to 90% of the population, it has already killed the most vulnerable.  I personally do not favor that use of that term, nor that strategy, because the human cost is too high.  


Do you have advice for workers on the front lines of this epidemic?

In an outbreak, there are a lot of ups and downs. Dealing with the frustrations, the uncertainties, and the changes take a lot of mental energy. It’s important to be gracious to others. Even if you don’t agree with what they are doing, trust that they are doing their best in their circumstance. Well, trust but verify! We do not have to react to things. We can respond to things, out of a place of peace and trying to make a difference for people.  

We need to keep health care workers healthy and functioning. Obviously having good access to personal protective equipment and good infection control practices is important, but really for the long haul of the outbreak, just take care of yourself physically and emotionally. Eat real meals instead of fast food or stress eating. Stay hydrated, especially in hot weather. Remember that life doesn’t stop, and that when the initial adrenaline of the crisis is over, you still have to function. Take a nap, take the stairs, take walks, take in nature. Just realizing sometimes that there is still a lot of beauty in the world just helps you recharge and keep going, even in the midst of a lot of suffering and hardship. 

Believing in what you do makes a difference in not burning out. You are in this for the long haul, taking care of yourself is part of taking care of patients.