#106 - Amesh Adalja, M.D.: Comparing COVID-19 to past pandemics, preparing for the future, and reasons for optimism
Amesh Adalja, M.D., a senior scholar at Johns Hopkins Center for Health Security, discusses COVID-19 in historical context, comparing it to past pandemics. He covers early virus spread, testing failures, the role of government, and future pandemic preparedness, emphasizing lessons learned and reasons for optimism.
Deep Dive Analysis
17 Topic Outline
Amesh Adalja's Background in Pandemic Preparedness
Initial Assessment of COVID-19 in December 2019
Early US Presence and Challenges in Containing the Virus
COVID-19 Compared to Past Flu Pandemics (1957, 1968, H1N1)
COVID-19 as a Potential Fifth Seasonal Coronavirus
Vaccine Specificity for SARS-CoV-2 vs. Pan-Coronavirus
Estimating the True Case Fatality Rate of SARS-CoV-2
Critique of Early Pandemic Modeling Predictions
Role of Local vs. Central Government in Pandemic Response
Failures and Bureaucratic Hurdles in Early Diagnostic Testing
Optimism for Future Pandemic Preparedness Post-COVID-19
Tailoring Pandemic Policies to Local Conditions
Mass Gatherings as Drivers of Virus Spread
Lessons from the HKU1 Coronavirus Discovery
Analysis of Sweden's Herd Immunity Strategy
The Role and Efficacy of Masks in Public
Positive Trends and Reasons for Optimism
5 Key Concepts
Severity Bias in Testing
This occurs when diagnostic testing is limited to only severe cases or individuals with specific risk factors, leading to an underestimation of the true number of infections and an overestimation of the case fatality rate. It makes it difficult to understand the actual prevalence and impact of a virus in the general population.
Biological Dark Matter
This term refers to the vast number of undiagnosed or uncharacterized infections that go unnoticed due to a lack of specific diagnostic testing for many infectious disease syndromes. People often present with common symptoms like colds or flu, and the specific virus is rarely identified, leaving a gap in our understanding of circulating pathogens.
Locally Managed, Federally Coordinated Response
This describes an ideal pandemic response framework where local health departments, with their intimate knowledge of their communities and capacities, lead on-the-ground efforts. The federal government's role is to coordinate and provide overarching guidance for the nation as a whole, ensuring a cohesive yet adaptable approach.
Herd Immunity Strategy
This approach involves allowing a significant portion of the population to become infected and develop natural immunity to a virus, aiming to reach a threshold where the virus can no longer spread effectively. It typically involves protecting high-risk groups while allowing others to be exposed, but carries risks if healthcare capacity is overwhelmed.
Case Fatality Ratio (CFR)
The proportion of individuals diagnosed with a disease who ultimately die from it. This number is an average and varies significantly based on factors like age, underlying health conditions, and the severity bias in testing, meaning it does not represent the risk for every person equally.
15 Questions Answered
Amesh Adalja realized the virus was transmissible human-to-human upon seeing the Lancet paper, which showed the first case on December 1st had no contact with the Wuhan wet market, suggesting it had been spreading since mid-November in China.
While not ruling out sporadic, mild cases mixed into flu and cold season, phylogenetics suggest widespread presence in the US likely began in January 2020, with New York's introduction primarily from Europe, not China.
COVID-19 shares similarities with past flu pandemics (e.g., 1957, 1968) in respiratory transmission and symptoms, but it is additive to the existing flu burden and has a lower case fatality rate than highly pathogenic avian influenzas, though higher than seasonal flu.
Yes, Amesh Adalja suspects SARS-CoV-2 will become the fifth seasonal coronavirus, circulating annually and causing about 25% of colds, similar to the other four common coronaviruses, due to its efficient transmissibility and intermediate severity.
Current vaccine development is specific to SARS-CoV-2, but there might be some cross-reactivity with other beta coronaviruses. A pan-coronavirus vaccine would be ideal, as coronaviruses are generally more stable than influenza viruses.
Based on extensive testing in places like Germany and modeling studies, the true case fatality rate is likely in the range of 0.3% to 0.66%, though this is an average and varies significantly by age (e.g., 15% for over 80, 0% for 8-year-olds).
Early models likely overstated the hospitalization rate, using a denominator that included only symptomatic cases rather than all infected individuals. Real-world data from places like Westchester County suggested a lower hospitalization rate of around 5%, significantly altering predictions for ICU beds and ventilators.
The ideal system involves a locally managed, federally coordinated response, where local health departments lead on-the-ground efforts due to their community knowledge, and the federal government provides overall guidance and coordination for the nation.
Early testing was hampered by restrictive federal guidance (only for travelers to China with severe symptoms), bureaucratic hurdles that prevented university and commercial labs from developing tests, and delays in FDA emergency use authorization for CDC tests, leading to widespread scarcity and delayed identification of community spread.
Amesh Adalja is optimistic that the severe economic and personal disruption caused by this pandemic, unlike previous outbreaks like H1N1 or Ebola, will compel the public to demand better pandemic preparedness from policymakers, making it a perpetual priority.
Yes, policies should be heterogeneous and dependent on local conditions, including transmission rates, population antibody status, hospital capacity, and diagnostic testing availability. A one-size-fits-all approach is not appropriate, and some areas can begin relaxing restrictions sooner than others.
Mass gatherings are problematic because they bring people from diverse geographic regions into close proximity, often involving shouting, screaming, eating, and drinking, which facilitates particle transmission. Attendees then disperse, potentially spreading the virus widely.
The HKU1 coronavirus, discovered after SARS, was found to be widespread globally once specifically sought, often causing pneumonia and even deaths, despite having 'flown under the radar.' This highlights the 'biological dark matter' of undiagnosed respiratory viruses and the need for better diagnostic curiosity.
Amesh Adalja is concerned about Sweden's per capita ICU bed numbers and the potential for their hospitals to be overwhelmed, despite their aim for herd immunity. Successfully cocooning high-risk groups while allowing widespread infection is a daunting and challenging task.
Amesh Adalja is generally not supportive of widespread public mask-wearing, especially N95s due to supply issues and discomfort. He questions the efficacy of homemade masks for asymptomatic spreaders and worries about potential negative behavioral changes (e.g., less handwashing, reduced social distancing). However, he acknowledges they may be used politically to facilitate reopening.
26 Actionable Insights
1. Sustain Pandemic Preparedness Funding
Advocate for sustained funding and prioritization of pandemic preparedness, viewing it as a perpetual national security concern rather than a reactive measure, to avoid the cycle of reactive funding followed by neglect.
2. Demand Preparedness from Policymakers
Demand that policymakers prioritize pandemic preparedness as a platform issue when voting and asking about future plans, remembering the economic and personal disruption caused by outbreaks.
3. Prioritize Local Public Health
Adequately resource and empower local health departments, as they are best positioned to manage outbreaks due to their intimate knowledge of their communities, capacities, and gaps.
4. Improve Diagnostic Testing & Tracing
Enhance diagnostic testing, case finding, and contact tracing capabilities to effectively contain future outbreaks, as current resilience to infections was overestimated.
5. Test Mild Cases for Containment
Test mild cases of infectious diseases, not just severe ones, because mild cases can be highly contagious and contribute significantly to unabated spread.
6. Streamline Diagnostic Test Availability
Streamline bureaucratic processes and emergency use authorizations to ensure rapid and widespread availability of diagnostic tests during a public health emergency, avoiding delays seen previously.
7. Broaden Testing Criteria
Broaden testing criteria for respiratory viruses beyond severe symptoms or specific travel history to catch early and varied introductions of a pathogen, preventing widespread undetected spread.
8. Critically Evaluate Scientific Models
Critically evaluate scientific models by understanding their underlying assumptions, as small differences can lead to big changes in outcomes. Use models as tools to be revised with real data, rather than as absolute truths.
9. Implement Locally Managed Response
Implement a public health response that is locally managed but federally coordinated, leveraging local knowledge and capacities while providing national guidance and setting the tone.
10. Tailor Policy to Local Conditions
Tailor public health policies and restrictions to local conditions, considering factors like transmission rates, population immunity, hospital capacity, and diagnostic testing availability, rather than a one-size-fits-all approach.
11. Avoid Mass Gatherings Pre-Vaccine
Avoid mass gatherings until a vaccine is available, as they disproportionately drive disease spread by bringing people from wide geographic areas into close, interactive contact, potentially putting a town over the edge.
12. Understand Mass Gathering Risk Factors
Be aware that activities involving shouting, screaming, eating, and drinking in dense social settings significantly increase the risk of virus transmission at mass gatherings.
13. Prepare for Widespread Transmission
Prepare for a respiratory virus to be everywhere once efficient human-to-human transmission is confirmed, especially if it has had a head start in spreading undetected.
14. Anticipate Seasonal Virus Recurrence
Anticipate that novel coronaviruses may become seasonal, circulating annually like other common cold coronaviruses, and prepare for successive waves.
15. Learn from Other Regions’ Experiences
Learn from the experiences of other regions that have faced outbreaks to better gauge local testing and hospital capacity responses, adapting strategies based on their successes and challenges.
16. Cocoon High-Risk Groups
Implement strategies to protect (cocoon) high-risk individuals, such as the elderly and those with underlying medical conditions, from infection, though acknowledging it is challenging.
17. Reopen Elective Services Judiciously
Consider reopening elective surgeries and clinics in areas not inundated by an outbreak, as delaying these services can lead to other significant health consequences not captured by pandemic models.
18. Broaden Essential Business Definition
Broaden the definition of “essential” or “life-sustaining” businesses during shutdowns to mitigate economic impact and other societal costs, looking beyond current restrictive lists.
19. Evaluate Safe School Reopening
Evaluate the safe reopening of schools based on local conditions, acknowledging that widespread school closures were controversial and not universally supported by experts.
20. Mask Use for Sick Individuals
If you are sick with respiratory symptoms such as a cough, fever, sneezing, or sore throat, wear a mask when in public to prevent spreading illness to others.
21. Avoid Mask-Induced Complacency
Be mindful that wearing masks should not lead to complacency in other protective behaviors like hand washing and social distancing, and ensure proper mask handling to avoid contamination.
22. Caution with Homemade Masks
Exercise caution regarding the effectiveness of homemade masks for asymptomatic individuals, as their ability to prevent spread is uncertain and they may not effectively block coughs and sneezes.
23. Improve Diagnostic Curiosity
Improve diagnostic curiosity and testing for respiratory viruses to better understand their prevalence and prevent surreptitious spread, as many go undiagnosed due to “biological dark matter.”
24. Interpret CFR with Nuance
When interpreting case fatality rates (CFR), remember they are average numbers and individual risk varies significantly by age and other factors, so not every person carries the same risk.
25. Invest in Pan-Coronavirus Vaccine
Invest in research for a pan-coronavirus vaccine, as coronaviruses tend to be more stable than influenza, potentially offering cross-protection against multiple current and future threats.
26. Conduct Retrospective Sample Analysis
Conduct retrospective studies by looking at bank samples to understand how prevalent a virus was before it was widely recognized, helping to map its early spread.
5 Key Quotes
I'm a little more worried about our pandemic resiliency based on how badly we've handled a 1% case fatality rate pandemic virus.
Amesh Adalja
All models are going to be wrong. Some of them are going to be useful, and some of them are not going to be useful.
Amesh Adalja
You have a locally managed, federally coordinated response, which I think is the best way to think about how it would be ideally done.
Amesh Adalja
We really have this biological dark matter everywhere.
Amesh Adalja
Mass gatherings, because of the density, because of the fact that people come from different geographic regions and then disperse, are a particular problem when it comes to communicable infectious diseases.
Amesh Adalja