How to Control the Spread of COVID-19 in Non-COVID Hospital Units: Takeaways from the Study on Healthcare-Associated Transmission


The pandemic surged in New York City from March through June, transforming the established norms of healthcare in an instant. At that moment, life in the epicenter was a day by day pursuit. We were building ICUs in real time to care for patients in dire need of ventilators. Fighting the clock to secure enough beds by mechanically converting ORs to ICUs, virtually doubling our ICU capacity overnight. 

Hospital-wide protocols were swiftly implemented to control the spread of infection and protect patients and staff. Part of the plan was to keep two designated Non-COVID units for critically ill COVID-free patients and emergencies: The Cardiothoracic ICU and adjacent step-down unit.

Incredibly, even as testing was scarce and PPE critically low throughout the worst of the peak, the COVID-free units were kept safe. Of 710 patients admitted to these units between March 1st and June 28th, only 3 patients were determined likely to have contracted COVID-19 while in the hospital. That’s 0.42 percent.

Here’s how they did it. 

A conversation with anesthesiologist Lauren Sutherland, MD, and heart surgeon Hiroo Takayama, MD, PhD, authors of the on-going study on healthcare-associated transmission.

Let’s start with some background on the study. How did this come about?

Dr. Sutherland: This came about as a kind of quality assurance project, more than a study. Columbia was right in the middle of the pandemic and our ICUs were really quickly filling up with patients with COVID-19. So we felt it was really important to preserve a couple of our ICU and floor spaces as non-COVID units. And because our CT ICU at 5 Garden North had a large population of transplant and immunocompromised patients, we decided to try and maintain these as COVID free.

And of course, as the pandemic went on we wanted to look back and see how we were doing. We wanted to see how many patients who passed through these units contracted COVID-19 as healthcare-associated infections. This knowledge is really important for guiding our reopening of the hospital, and especially cardiac surgery after the peak of the pandemic in New York City passed. We wanted to have that information to give to patients about their risk of being in the hospital.

How did you analyze patient data to determine where they contracted Covid-19? What were the categories you used to determine the likelihood of hospital transmission?

Dr. Sutherland: We basically define likeliness of healthcare-associated infections in our non-COVID units in four categories: likely, possible, unlikely, or not possible. 

Not possible applied to patients who tested positive prior to admission or within 24 hours of admission. Unlikely was patients who tested positive early in their course or a long time after discharge (so the timeline didn't quite make sense for a nosocomial infection from these units). Possible was used to define a reasonable time course where it may have been acquired in our unit, but also with a stay in another unit or place where the infection could have been acquired. And finally, likely was when the time course of infection matched up with the stay in our unit, and there wasn't exposure to another place where the infection may have been acquired. 

Then as a group we discussed the data with an infectious disease specialist that was part of the QA committee. We would go through the time course of the positive tests and any potential antibody tests, as well as any exposures to our floor or ICU, as well as other floors ICUs, or time outside of the hospital. And as a group came to a consensus of what category we felt that the case fit into.

Tell us about the protective measures. What protocols have been implemented that you can connect to such a low rate of Covid-19 contraction in the hospital?

Dr. Sutherland: These really evolved over the course of the pandemic. A big part of it was adequate testing. As testing became more available, patients were tested prior to coming to the non-COVID units, and then eventually all patients who were admitted to the hospital received COVID testing. And then anytime a patient on a unit designated COVID-free developed symptoms, they were retested again. So being able to test early and more frequently was really important.

Another aspect was proper use of PPE in the hospital. Early on, we implemented contact and droplet precautions for any patient with COVID-19 or patients under investigation, as well as airborne precautions using N95 masks and negative pressure rooms whenever possible, and especially for aerosolizing procedures. Later in March, we implemented the universal masks-on policy for all staff when information started to come out that this could be really helpful in preventing the spread.

Finally, we took some practical precautions, like limiting foot traffic between our CT ICU with the adjacent ICU that had COVID-19 patients, by literally closing off the door. We also would quickly isolate and move out any patient that was diagnosed as COVID-positive. And then in any patient care situation, we limited room entry to only essential staff and procedures.

Was each aspect of these protective measures implemented gradually?

Dr. Sutherland: Yeah, this was all gradual as we had more availability of PPE and more testing. And as we had more knowledge as to what would actually help prevent the spread. Early on testing was very limited, only patients that had symptoms were tested. But once swabs became more readily available, everyone was tested before they came to the non-COVID ICUs or even into the hospital at all.

In terms of PPE, we never ran out, but the supply was definitely low at one point. So early on, before we really knew how COVID-19 was spread, a mask would be placed on a patient with symptoms prior to transport or coming in contact with staff. But later on, it actually switched, so that staff would wear the masks and we had a lot more availability of N95s for airborne precautions.

Healthcare workers weren't included in this study. How does that exclusion impact the data?

Dr. Sutherland: Because of privacy concerns, we never were able to look into healthcare worker infection rates, but I know for a fact that we had some. And the fact that our patients stayed safe despite this really says a lot. We protected ourselves from exposure to any potentially sick patients, but we also protected the patients from us by keeping our masks on during any patient care.

The results of this study are really extraordinary. Did the data surprise you?

Dr. Sutherland: Initially, I was a bit surprised because the rates of COVID-19 were so much higher than we expected at the beginning. There were so many cases that were undiagnosed right at the beginning of March. I thought there might've been a higher chance that we were possibly seeing some nosocomial spread of COVID-19. 

But once we started really implementing transmission precautions and having appropriate PPE, I think everybody was very careful. So, in that sense, I'm not surprised that our rates stayed low. But it also just shows how great our staff is. How careful everyone is with sanitizing, with cleaning, wearing appropriate PPE to prevent the spread.

Dr. Takayama: Lauren and the ICU team, including all the nurses and everybody did an amazing job. And this also came from the leadership of the hospital and our group. Our CT ICU and cardiac surgery step-down unit were two of the very, very rare units in the entire city that were kept COVID-free as much as possible throughout this pandemic. As Lauren said, I was not super surprised to see the safety information of it. At the same time, confirming how safe it was, and it is, and it is even improving, is extremely reassuring for ourselves. And of course, for our patients too.

How does this affect future plans to protect patients and control the spread? Has the data changed the way you're assessing procedures or policies?

Dr. Sutherland: I think it shows that what we've been doing works. Especially at the peak of the pandemic, when there was such a high rate of COVID-19 in New York City and in our hospital. The fact that we were able to keep this unit COVID-safe and not pass it on to our really high-risk populations makes me feel like we can continue to do what we're doing. Even if there is another peak in the future.

It shows that it's safe to hospitalize in-care for patients that are COVID-negative, even when they're having high-risk surgical procedures like transplants and other surgeries. Because we have a way to prevent spread between patients and between staff and to really keep those patients safe.

Dr. Takayama: I think our study can inform other institutions too. Number one, if there's an opportunity to create COVID-free units, I think that ensures a fairly COVID-free environment for the patients. And number two, subsequent to our published study, now we are gathering data from the patients who are admitted to what we call a “COVID unit” or “mixed unit.” There were many COVID patients, especially at the pinnacle of the pandemic, yet some of the COVID-free patients had to be admitted to those units for a variety of reasons. Their data is being analyzed as of now, but preliminary findings suggest that those patients also had an extremely low contraction rate.

That’s great to hear.

Dr. Takayama: So again, this would inform other hospitals in areas where the pandemic is occurring now that patient care can be done safely without using super excessive equipment for PPE to protect our patients. Again, we don't know the safety side of healthcare workers’ information. However, patients were kept safe based on the protocols and procedures that the ICU team in the hospital implemented.

Can you explain the difference between using the terms COVID-free and COVID-safe?

Dr. Sutherland: It's a good question. COVID-free is a goal, and I think it's not always possible to attain. There are cases where patients test negative initially and the test isn't perfect and then later test positive. So, while our goal is always to have the ICU COVID-free, COVID-safe is the reality of what we can actually achieve. And even despite having the occasional case of COVID-19 come up in our COVID-safe unit, we saw very low rates of transmission. I think that the most important part was that when these cases did occur, they were identified and moved quickly and the majority of patients stayed safe.

What are the units looking like now that positive test rates are so low in NYC?

Dr. Sutherland: Most units have very few, if any, patients with COVID-19 right now, but those units that have them are primarily mixed. And it’s encouraging from our very preliminary data in mixed units that those units seem to be very COVID-safe as well. The rate of healthcare-associated transmission seems to be quite low. We've still maintained our CT ICU and our 5 Garden North floors as COVID-free, but most of the other ICUs are mixed units.

That’s really encouraging. Do you plan to continue this study for the foreseeable future?

Dr. Sutherland: Yeah, I think it's a really great way to see how we're doing and to make sure that everybody is really sticking to the precautions and wearing PPE going forward. If we were to see any sort of increase in our rates, then I think that would be a cue to us to really reassess what we've been doing. And I think it's easy for everybody to get a little bit lax now that the numbers in New York City are down. But it’s really important that we continue to use these precautions to keep patients safe.

Dr. Takayama: I agree with that. In addition to the importance of continuing this current QA initiative, we do actually learn quite a bit since COVID-19 is a new entity. With more and more patients who are suspected to have a positive COVID test, we are finding more and more that those patients have previous histories of positive COVID contraction. And the antibodies are sometimes positive, sometimes negative, swabs are positive, negative. And sometimes it's all over the place.

Interpretation of that testing is becoming more and more complicated. During the pandemic, we are able to quickly assemble this multidisciplinary QA team, and I do believe that we will be able to think through this new information and perhaps come up with new recommendations or suggestions. Even for the diagnosis or interpretation of data or COVID testing results.

What’s the most important thing you want people to take away from this study? 

Dr. Sutherland: I want patients to know that keeping them safe is our focus and keeping the rate of COVID transmission in the hospital at zero is one of our biggest priorities in terms of providing good patient care.

Dr. Takayama: What I would like to emphasize to the community and our patients is that COVID is a new entity of disease and the data suggests that it is quite dangerous, especially if you are in a high-risk category. At the same time, there are a number of observations coming up and being published about the higher mortality rates of non-COVID diseases during the pandemic. And some of that, or much of that, seems to be coming from avoidance of coming to the hospital because of the COVID fear.

I do hope that our study gives some reassurance that coming to the hospital is not as dangerous as you or somebody else may think. And actually taking care of the disease as necessary is likely a lot more important than being afraid of being at the hospital. So again, we have to be careful and avoid interaction with the COVID environment, but even in the worst part of the pandemic, the hospital was able to keep COVID-free patients as COVID-safe as possible. So, do not ignore your symptoms, and if you need to come to the hospital, we encourage you to come to the hospital.

Dr. Sutherland: I think in a way the hospital is almost more safe than being out in the community because we have PPE, we have testing, and we know and diagnose who has COVID very quickly. Whereas in the community it's a little bit less sure. So, I would encourage that patients are, if anything, safer in the hospital. 

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