Wendy M. Bamberg, MD, the editor of Contagion®’s Emerging and Re-emerging Infections section, shares her thoughts on social distancing, managing suspect cases, and lessons we can learn about COVID-19.
Segment Description: Wendy M. Bamberg, MD, the editor of Contagion®’s Emerging and Re-Emerging Infections section, and principal and medical epidemiologist with Medical Epidemiology Consulting, shares her thoughts on social distancing, managing suspect cases, and lessons we can learn about COVID-19.
Interview transcript (modified slightly for readability):
Contagion®: Welcome to another Contagion® coronavirus video. Today we are joined by Dr. Wendy Bamberg, the section editor of Contagion’s Emerging and Re-emerging Infections section. Thanks for joining me.
Bamberg: Thanks for having me, I’m happy to be here.
Contagion®: So, Dr. Bamberg, you have a lot of knowledge about public health from your background in the field. What are some of the biggest challenges that we face when a novel virus such as SARS-CoV-2 emerges?
Bamberg: The first challenge is initial detection of a novel, emerging pathogen. We rely on early surveillance systems, including regional surveillance of symptoms (what we call syndromic surveillance) and astute clinicians who are on the front lines of delivering health care. In countries with weaker health systems, detection of a novel pathogen might be delayed. Additionally, the most devastating effects can be seen in countries with weak health systems, ongoing conflicts (as we have seen with Ebola in the Democratic Republic of the Congo), or other infectious disease epidemics.
Things we want to know early on include:
This helps public health determine what prevention measures to begin to implement.
Other challenges include:
As the pandemic spreads, other issues begin to emerge. Lack of supplies, such as personal protective equipment and reagents needed for testing, the safety of health care workers and other essential workers, and overwhelming the health care system become challenges. Ensuring timely, consistent, and accurate information also can be a challenge, as well as information overload.
Contagion®: From a public health perspective, can you speak to how important social distancing is right now?
Bamberg: In many places in the US, we have moved into a phase of mitigation, which means trying to slow the spread of disease when we might not be able to intervene for every case. Right now social distancing is critically important.
One way to understand the importance is to take the concept of the reproductive number (also called the R naught), which is the number of others that one infected person will, on average, transmit the disease to. Factors that influence the reproductive number include characteristics of the virus itself - how contagious it is and how susceptible people are to infection because of those characteristics. We can’t influence these factors. There are factors that influence the reproductive number that we can affect - the number of contacts between people and the duration of those contacts. This is where social distancing comes in to decrease these effects.
Bamberg: Another important consideration for social distancing right now is the effect that asymptomatic transmission is having on the spread of the virus. If the virus was only spread when people had symptoms, it would be easier to identify who had the virus and isolate them. We are seeing more reports that the virus can be transmitted before symptoms develop; this might be asymptomatic transmission, if someone never develops symptoms, or what we are calling pre-symptomatic transmission, if someone later develops symptoms. An early report out of Singapore indicated that the virus might be transmitted between 1-3 days prior to symptom onset.
One other thing I would like to note, when we talk about the term “social distancing,” what we are really talking about is physical distancing; maintaining social connections using technology is so important during this physical distancing period.
Contagion®: It seems that in the United States the New York area is the hardest hit. Do you think public health officials in other states can use the lessons learned in New York and apply them to response in areas that are starting to see an increase in cases?
Bamberg: Public health officials are absolutely watching what is happening not just in their jurisdiction, but also what is happening across the US and around the world. The entire public health and health care community continues to learn from each other. Not just lessons from New York, but lessons from Italy, China, South Korea, and other states like California and Washington.
What we seem to be seeing is that early social, or better said physical, distancing seems to be working. It does take time to see that effect since the incubation period for COVID-19 averages around 4-5 days but can be anywhere between 2-14 days. As we begin to see evidence that cases are leveling off and then decreasing, and once distancing restrictions are loosened, public health officials will be able to watch what happens across the country and around to world to apply lessons learned to their own communities.
Contagion®: Can you provide an overview of how persons under investigation for COVID-19 are being managed?
Bamberg: The usual public health methods were employed initially. This includes the reporting of cases to public health, investigating those cases to make sure sick people are isolated, identifying contacts and then quarantining contacts with exposure. Also, local outbreaks are identified and investigated.
An early report from Santa Clara county in California used sentinel surveillance, which monitors an identified group of health care facilities, in this case 4 urgent care centers, for patients that develop a certain set of symptoms, in this case fever, cough and shortness of breath. They found 23% positive for influenza. A subset of persons testing negative for influenza were tested for COVID-19, and 11% were positive for the SARS-CoV-2 virus. In this way they were able to establish community transmission was occurring within their community.
As cases increase, it does become impossible for public health to investigate every case, and so other strategies might need to be used. For football fans, this might be analogous to zone defense instead of man-to-man. This is the phase much of the US is in right now, and interventions include physical distancing, public messaging, reliance on health care providers to relay information to patients regarding isolation and quarantine for the ill and exposed. When not everyone can be tested, there is a need to also begin to understand who might be ill with the disease even when they can’t be tested - these might be classified as suspected or probable cases. Other types of surveillance strategies that might collect information in this phase include sentinel surveillance (which is using a subset of health care facilities to understand what might be happening in the whole community), syndromic surveillance (which is using a set of symptom criteria to identify suspect and probable cases), monitoring hospitalizations and ICU-admissions, and mortality-based surveillance which might include reviewing death certificates.
As mitigation strategies begin to work, and the curve levels off, the post-suppression phase begins. During this phase we hope that public health might be able to switch back to strategies used initially, including the investigation of individual cases, identification of contacts, and the use of isolation and quarantine. During this phase, we hope to see increased capacity for testing, a variety of surveillance systems to capture probable as well as confirmed cases, and less strain on the health care system. By the time we get to this phase, cases are at a manageable level and systems are in place to respond to suspected cases to get them diagnosed and isolated, and contacts identified and quarantined.
During all of these phases, it is important to consider the ability of individuals and society to maintain isolation and quarantine practices. We must consider the most vulnerable among us, such as persons experiencing homelessness and populations that are underserved in our health care system, and remember to address issues of health equity.
Contagion®: This is obviously not the first and not the last pandemic that the world will see. What should we be taking note of to better prepare for next time?
Bamberg: The interesting thing about public health is that when it’s working and systems aren’t stretched past capacity, you don’t know it’s there. It is so important in between crises that public health systems are maintained. This includes maintaining expertise, resources, supplies, and programs that can prepare in between crises and respond during a crisis. It is too easy to decrease public health programs when there isn’t a crisis, and then we are slower to respond when a crisis develops. It is also important to factor in supply chain issues, health care worker safety, and surge capacity needs, all thing we are seeing stretched past the limit in the current pandemic.
Contagion®: Any final thoughts?
Bamberg: I’m struck by how health care and public health are working so closely together. There are so many heroes: environmental services, dietary staff, support staff, and health care workers who are all on the front lines in health care; public transportation workers, grocery store employees, delivery services - all of whom work to keep society running. I’d like to take a moment to thank everyone who is working, directly and indirectly, to support our society during this pandemic.
Contagion®: Thanks so much for joining us.