COVID-19 No "Worse" than The Flu?

It is very common these days for people with varying motivations to make the argument that that COVID-19 the current pandemic caused by the SARS-CoV-2 virus is no worse than seasonal influenza.  After presenting that premise, the conclusions are typically that there is really no reason to implement social distancing, stay at home orders, and all of the additional precautions currently in place to prevent the spread of the virus.

The important qualifier here is the need to include how deaths from both illnesses are estimated.  The CDC is very clear that it does not know the exact number of influenza deaths each year but it estimates them from statistical models. This is nothing new and they have been using this procedure for decades.  The reasons include the fact that influenza deaths are not reportable at a national level, although pediatric influenza deaths are.  It is also not possible to know if influenza is the proximate cause of death because the death may occur weeks later as a result of a secondary infection or an exacerbation of a chronic medical condition by the influenza infection.  In these cases, influenza may not be listed as a secondary infection.  Finally - not everyone who dies from an influenza-like illness (ILI) has influenza and not everyone who dies from ILI is tested for influenza. The influenza death estimates are not based on death certificates for that reason.  

There is considerable variability in mortality estimates based on the model being used.  A description of their current methodology and its limitations is available at this link.   There is a similar limitation of COVID-19 related deaths and the CDC has a specific reporting procedure suggested for that process.  CDC clinical criteria and lab testing is further specified to determine if COVID-19 is an underlying cause of death. COVID-19 can be reported as "probable" or "presumed" based on clinical judgment.  Three examples are given in the linked document in how to fill out the death certificate. The main difference is that COVID-19 mortality depends on deaths certificates and influenza mortality does not.  At least for now.

Looking at the CDC death rate estimates for influenza over time looks like this (click to enlarge any graphic):

But looking at the raw data based on death certificates looks like this:

Looking at the typical influenza season going from 2019 (week 43) to 2020 (week 15) shows that the raw death certificate data for pneumonia is 90,369 and for influenza it is 7,591.   


The argument typically is made looking at disease mortality and the raw number of deaths are not used. The CDC and other agencies report rates per 100,000 to correct for differences in population.  The current mortality rate for COVID-19 as of today is shown below - even though the lead graphic illustrates that deaths are continuing to increase at this point.:


COVID -19 Deaths  CDC Page

Total Deaths: 37,158

Death Rate/100,000: 11.3

First Case January 21,2020


Influenza Deaths

Total Deaths:  24,000 - 62,000  2020 estimate based on above data and methodology

Death Rate/100,000:  7.3 - 18.9

First Case October 2019


The second consideration is that the COVID-19 pandemic is clearly not over. Different geographic areas in the US are at different points in the curve that depicts new cases.  The key point on that curve is the inflection point where the new cases per day go from a linear increase to an exponential one.  A panel of 20 experts in infectious disease modeling was referenced as the source for a recent White House estimate of 240,000 deaths by the end of 2020 (8).  If you look at that reference there is a wide confidence interval.  That is four times the CDC estimate of 2020 influenza deaths.  For comparison there were 675,000 deaths in the USA in the 1918 pandemic.

How does this information assist with the analysis of rhetoric?

1.  COVID-19 is no worse than seasonal flu: 

First off, influenza is a severe infection and can't be trivialized. Everyone who is able to should get an influenza vaccination. Based on the available data - is certainly seems that COVID-19 is as bad and much worse in the worst case scenario.  It is at least on par with modern CDC influenza death rates estimates over the past 20 years and based on the current number of deaths is likely to exceed the 2020 estimate for influenza deaths.  The outliers for the White House estimate in the survey are much higher - in some cases exceeding the mortality from the 1918 pandemic.  These estimates are also based on current rates and if the country is "opened" and stay-at-home orders, wearing masks and social distancing guidelines are abandoned it is very likely that there will be secondary spikes and prolonged exposure to the virus. Does anyone really want to take the chance of this virus killing more people than the 1918 pandemic?  

2.  COVID-19 rates are inflated based on inaccurate reporting:

This meme was reinforced by a physician appearing on a conservative talk show who stated that he only reports what he considers to be the underlying cause of death on death certificates.  The example given was that if the patient died of pneumonia - the cause of death was pneumonia and would not speculate on what caused the pneumonia.  The implication being that death certificates are highly accurate and the suggested reporting guidelines for COVID-19 will result in over-reporting the condition.  The information clearly shows that this is not the case. The actual numbers of deaths due to influenza as reported on death certificates are a fraction of the number estimated by the CDC.  The CDC plainly states that they have no idea how many people actually die from influenza and for decades they have estimated the number based on hospitalizations, hospital mortality, and other surveillance numbers.  COVID-19 death counts are made on the basis of death certificates.  Even though death certificates are not perfect, it is likely that many more people who die from COVID-19 are tested than people who die from influenza. It will be interesting to see if the CDC develops statistical models for COVID-19 to see if the current deaths are an underestimate like influenza. 

That is my brief look at these two arguments that are being used to suggest that the current environmental approach to virus containment are unnecessary.  I am also reminded of an old statistical concept called face validity.  Briefly stated that would mean the null hypothesis of no difference in death rates makes sense.  Given that COVID-19 has risen to the highest daily cause of death in the US, that hospital and ICU beds in many locations are overwhelmed, that there is a catastrophe in New York City at this point, and it has led to the only mass shortage of personal protective equipment, ventilators, and medical gear that I can recall in my 3 decade career - I don't think that it does make sense.

And this is exactly not the time to trivialize this pandemic.


George Dawson, MD, DFAPA


References:

1: CDC:  Frequently Asked Questions about Estimated Flu Burden.  Link

2: CDC:  Estimating Influenza-Related Deaths.  Link

3: National Center for Health Statistics. Guidance for certifying deaths due to COVID–19. Hyattsville, MD. 2020. Link

4: Reed C, Chaves SS, Daily Kirley P, Emerson R, Aragon D, Hancock EB, et al. Estimating influenza disease burden from population-based surveillance data in the United States. PLoS One. 2015;10(3):e0118369

5: Rolfes, MA, Foppa, IM, Garg, S, et al. Annual estimates of the burden of seasonal influenza in the United States: A tool for strengthening influenza surveillance and preparedness. Influenza Other Respi Viruses. 2018; 12: 132– 137. https://doi.org/10.1111/irv.12486

6: Centers for Disease Control and Prevention. Estimated influenza illnesses and hospitalizations averted by influenza vaccination – United States, 2012-13 influenza season. MMWR Morb Mortal Wkly Rep. 2013 Dec 13;62(49):997-1000.

7: Reed C, Kim IK, Singleton JA, Chaves SS, Flannery B, Finelli L, et al. Estimated influenza illnesses and hospitalizations averted by vaccination–United States, 2013-14 influenza season. MMWR Morb Mortal Wkly Rep. 2014 Dec 12;63(49):1151-4.

8:  Thomas McAndrew Spring March 25, 2020 COVID19-Expert ForecastSurvey6-20200325.pdf 


Graphics credit:

Lead graphic is from Our World in Data licensed under Creative Commons BY-SA and may be freely used for any purpose. 

All others are from the CDC under public domain.

SARS-CoV-2 is an Airborne Virus?

I thought I would say something more about airborne viruses. They have been a hobby of mine for some time.  The first time I heard about how easily the current coronavirus was spreading I thought “this is an airborne virus”. But then there were the usual protests. Some scientists came out and said that coronavirus requires “droplet” precautions rather than “airborne” precautions. The common definition is that droplets are large enough settle out quickly. They may touch you directly if you are close enough but a lot of what droplets do is settle on surfaces. That leads to surface contamination and spread of the virus.  Airborne viruses can travel longer distances within smaller droplets. An even more unique characteristic is that airborne viruses are released with normal expiration. No coughing, sneezing, or shouting is necessary. Just normal breathing can release airborne respiratory viruses into the air in the smallest droplet fraction.

An easy way to conceptualize airborne viral spread is to look at the distribution of particles occurring with every breath. They can range in size from 200 µm on the large end to less than 5 µm on the lower end. Experiments can be done to show how aerosols of these particle sizes spread through a room. Naturalistic experiments can also look at how these are all spread through hospitals, airplanes, and other natural settings. By looking at those patterns and the distance involved as well as any other paths that could lead to transmission – a determination can be made about whether or not a viruses “airborne” or not.

The second issue is whether or not live infectious virus is spread by these droplets. In many cases that has been limitation in the experiments. Direct evidence of viral spread at a distance requires culture of the virus or a bioassay that shows the samples have a cytopathic (killing) effect on live cells. Indirect evidence is typically by PCR where the available nucleic acid is amplified and assayed.  In researching this topic, I found early literature that documented numerous respiratory viruses in ventilation systems of buildings. That research was possible because nobody knew how to capture and culture the virus samples until that time. The other technical issue is air sampling. Certain air sampling devices do not allow for adequate virus detection. There is a technical report recently that showed of a total of four commonly used air sampling devices only one allowed virus to be identified or cultured. These technical constraints have led to a lot of confusion about whether a particular virus is airborne or not.

A practical definition of an airborne virus is one that is exhaled during normal breathing can travel a distance in small droplets (less than 5 µm) and create infection by landing on mucosal surfaces, facial services, or the lining of the nasopharynx, oropharynx, or lungs.  In that case you don’t have to be in the presence of anyone coughing or sneezing. You don’t have to touch any contaminated surfaces. You don’t have to touch your face. You just have to breathe contaminated air. It is entirely possible that you can walk through a cloud of airborne virus and not be aware of how it got there. A common example is walking down the hallway after a crowd of people have walked through some of them carrying the virus. Once you know about airborne viruses it gives you an entirely different perspective on social distancing.  Airborne particles can easily transverse the longest dimension of typical rooms. The distance of 6 feet suggested in typical social distancing guidelines is not nearly far enough.

In a previous post I highlighted an experiment by Donald K. Milton where he designed a machine to sample flu viruses in a natural setting. Research subjects breathed normally and their expired air was sampled for influenza virus. Influenza virus was recovered from 89% of the nasopharyngeal swabs and 39% of the fine aerosol sample defined as droplets less than or equal to 5 µm and greater than 0.05 µm. There was no coughing or sneezing during the collection.. That is proof that influenza virus is airborne.

A recent experiment carried out at the University of Nebraska Medical Center (3) in their bio containment and quarantine units showed that in addition to abundant surface contamination by SARS-CoV-2 the virus was also present in hallway air samples, in areas where only aerosol deposits could reach, and personal air samplers carried by staff.  The virus was detected by PCR analysis as well as culture in some cases. The authors concluded that this was definite evidence of an airborne virus and that facilities treating patients with SARS-CoV-2 should use airborne precautions. This paper is currently undergoing peer review and is on a preprint server.

The technical aspects of aerosol fractionation and dispersion is a subject best addressed in the engineering literature. The best paper I could find on the subject (4) had a goal of studying the dispersion characteristics of exhaled droplets in a ventilated room. The engineering goals are to find out what physical parameters affect the dispersion rate and hopefully lead to better indoor environments. The experimental paradigm looked at a room that was 5 x 4 x 3 m (L x W x H) and ventilated by a downward airflow from the ceiling. Aerosols were injected into this room and the following distance and trajectory along with trajectory time was calculated for the fractional droplets. As expected droplets with larger diameters (110-115 µm) fell at a faster rate and traveled a much shorter distance than the smaller diameter fraction. Droplet dispersion was studied under a number of physical conditions including different airflow, different temperatures, different relative humidity, and the original exhaled initial velocity.

The 0.1, 1.0, and 10 µm droplets covered horizontal distance of 5 m or the entire length of the room. Droplets in the range of 50 to 200 µm cover distances ranging from 0.5 to 4 m.  This study has numerous excellent graphs about varying conditions and how droplets in different fractions are dispersed. The reader is referred to the original reference to review all those conditions. The bottom line for me was it is clear that airborne droplets in the 0.1 to 10 µm range are commonly seen in exhaled air and easily covered distance in this experiment of 5 m or (for Americans) 16.4 feet. That is well beyond social distancing recommendations it explains why this virus continues to spread. Within the past week I have seen clips of New Yorkers in congested subway cars.  Any asymptomatic SARS-CoV-2 carriers in those cars are expelling virus into the air just by tidal volume breathing.  Coughing and sneezing is not required. It would be very good if you covered your cough or sneeze but when your mouth is not covered and you are a symptomatic or asymptomatic carrier you are exhaling viral particles.

The relevance of this virus being airborne cannot be underestimated. It is a substantial part of the reason behind social distancing and stay-at-home orders. It is the reason for the new recommendation to wear masks in public and the various explanations being given for those masks. The absolute best approach is to not have any close social contact until this pandemic is over. I am very concerned about my colleagues and fellow healthcare workers who have inadequate personal protective equipment (PPE). The expectation is that they will continue to take care of the very ill patients with COVID-19. Every effort must be made to make sure they have adequate protection. 

In my particular specialty, all psychiatrists should have access to electronic interviewing at this point. As I pointed out in my earlier posts, I am used to talking people for 30 to 60 minutes at time. Some of those evaluations are 90 minutes in duration. During that time the patient may be coughing or sneezing but for the most part they are breathing and engaged in normal interview conversation. My office is smaller than the room described in the droplet dispersion experiment. By the end of one interview, the smallest fraction of exhaled droplets is dispersed throughout the room. Any viral particles in that fraction can lead to infection.

All health care workers in these environments need immediate protection by the implementation of airborne precautions. I am hopeful that as more people become aware of the airborne route of transmission that it will lead to more caution on the part of the public and the social distancing and staying at home and away from this kind of transmission will make more sense. In the future we need to design indoor environments that can minimize this type of transmission. There is too little innovation in the role of the physical environment in airborne transmission of infectious illness.

I hope the added cost will be looked at in terms of the total cost of illnesses caused by respiratory viruses every year with the recognition that they can still cause devastating pandemics.

George Dawson, MD, DFAPA


References:


1: Lei H, Li Y, Xiao S, Lin CH, Norris SL, Wei D, Hu Z, Ji S. Routes of transmission of influenza A H1N1, SARS CoV, and norovirus in air cabin: Comparative analyses. Indoor Air. 2018 May;28(3):394-403. doi: 10.1111/ina.12445. Epub 2018 Jan 6. PubMed PMID: 29244221. 

2: Yu IT, Li Y, Wong TW, Tam W, Chan AT, Lee JH, Leung DY, Ho T. Evidence of airborne transmission of the severe acute respiratory syndrome virus. N Engl J Med. 2004 Apr 22;350(17):1731-9. PubMed PMID: 15102999.

3: Santarpia et al. (2020) Transmission potential of SARS-CoV-2 in viral shedding observed at the University of Nebraska Medical Center. Retrieved from https://www.medrxiv.org/content/10.1101/2020.03.23.20039446v2.

4: Chen C, Zhao B. Some questions on dispersion of human exhaled droplets in ventilation room: answers from numerical investigation. Indoor Air. 2010 Apr;20(2):95-111. doi: 10.1111/j.1600-0668.2009.00626.x. Epub 2009 Sep 24. PubMed PMID: 20002792.

5: Li, Y., Huang, X., Yu, I.T.S., Wong, T.W. and Qian, H. (2005), Role of air distribution in SARS transmission during the largest nosocomial outbreak in Hong Kong. Indoor Air, 15: 83-95. doi:10.1111/j.1600-0668.2004.00317.x

6: Carl Heneghan, Jon Brassey, Tom Jefferson. SARS-CoV-2 viral load and the severity of COVID-19.  March 26, 2020.  Link

7:  National Research Council 2020. Rapid Expert Consultation on the Possibility of Bioaerosol Spread of SARS-CoV-2 for the COVID-19 Pandemic (April 1, 2020). Washington, DC: The National Academies Press. https://doi.org/10.17226/25769.

"While the current SARS-CoV-2 specific research is limited, the results of available studies are consistent with aerosolization of virus from normal breathing."

8: Pan M, Bonny TS, Loeb J, Jiang X, Lednicky JA, Eiguren-Fernandez A, Hering S, Fan ZH, Wu CY. Collection of Viable Aerosolized Influenza Virus and Other Respiratory Viruses in a Student Health Care Center through Water-Based Condensation Growth. mSphere. 2017 Oct 11;2(5). pii: e00251-17. doi: 10.1128/mSphere.00251-17. eCollection 2017 Sep-Oct. PubMed PMID: 29034325.

9: Lu J, Gu J, Li K, Xu C, Su W, Lai Z, et al. COVID-19 outbreak associated with air conditioning in restaurant, Guangzhou, China, 2020. Emerg Infect Dis. 2020 Jul [date cited]. https://doi.org/10.3201/eid2607.200764

Graphics Credit:

Graphic is from Shutterstock per their standard agreement.

Acute-Care Psychiatry During the Pandemic

in the early days of this century, I spent a lot of time in Avian Influenza Task Force meetings. I was on two separate task forces and at the same time working on an acute care inpatient psychiatric unit. One of the meetings took up four hours in the afternoon and I would have to go back to my unit and make up those four hours. I made the mistake of that not saving all the documentation from those meetings. There were hundreds of pages. The main focus of one task force was on “surge suppression” or helping with crowd control to prevent emergency departments from being overwhelmed by people who did not really have the viral infection. The other meeting was more about the actual response to the viral infection. I was always skeptical of what I heard. We kept hearing that if there was an epicenter of infection, large pallets of Tamiflu would be on the way. We saw presentations with pictures of those pallets under plastic wrap. At the same time there was discussion about morgues and refrigerated trucks that have become part of the current crisis.

I was more concerned about what would happen to inpatient psychiatry units. I kept hearing that the medical and surgical beds would be overwhelmed. When I suggested that we increase the capacity of negative airflow rooms and rooms vented directly to outside air, I was told that was impossible. One expert gave the opinion that if there is an airborne virus in the hospital: “The minute you walk into the hospital you should be wearing an N95 mask”.

That was about 2005 and I had never heard of an N95 mask before that. I had certainly worn masks for painting, dust protection, and various chemical and biological experiments that I did in the course of education and research. I went out and bought a small package of N95 masks. I fitted them per the instructions and noticed a couple of things. The fit was extremely snug due to upper and lower elastic bands (that have a much smaller circumference than a human head or neck), the circular contour of the mask providing a suction fit to some extent, and a flexible metal band that bends over the bridge of the nose to effectively seal that area. When you are wearing an N95 mask your voice is muted and you are breathing against resistance. If you wear it long enough, it becomes soaked with exhaled droplets. I rapidly concluded that it would be nearly impossible to conduct a psychiatric interview wearing this mask.

I never really learned at the time whether there was a plan to shut down inpatient psychiatry and use all the beds for avian influenza patients. Thankfully it never got to that point. Flashing forward 15 years a real pandemic is upon us and the problems remain unsolved. Inpatient psychiatric units and residential drug and alcohol treatment units are considered necessary services in most states and they remain open. Very recent information from the authorities now suggest that SARS-CoV-2, the virus causing COVID-19 is airborne and that there are a significant number of asymptomatic carriers.

I have been using telepsychiatry at this point for two weeks and it seems to be going well. There are definite constraints compared with face-to-face interviews. I have noticed more constraints since my original post on this topic. I put a couple of questions out there on social media today to see how my colleagues who are still actively engaged in acute care are adapting to the changing parameters of this pandemic. Before putting those questions out, I had the thought that telepsychiatry could be used over the short distances in inpatient settings. As a resident I had the experience of observing psychotherapy firsthand and being observed from adjacent rooms that also had microphones for communication between those rooms. I was interested in seeing whether or not anyone had implemented those solutions.  I was pleased with the feedback that I have so far.

One of the first responses was that psychiatric staff were using surgical facemasks and face shields in some settings. In other settings, adjacent rooms and telepsychiatry both on-site and off-site were being used for acute-care units. The most unique solution I heard of was a consultation liaison team using iPads to interview medical and surgical patients remotely where possible. That reminded me that some people have joined my telepsychiatry sessions using smart phone apps. It was generally very suboptimal if the phone was not completely stabilized.  I also had the experience this week of getting a link sent to me from a colleague who worked for a large healthcare system. It was an invitation to open up a video session with him even though I am not registered in his clinic.  It was very similar to a Zoom session that I did for a podcast. All this information shows that there are technologies available right now that are effective and actively being used. They have also been very rapidly deployed or are in the process of being deployed. There is some potential that this sudden change in the delivery of psychiatric services may be a more permanent one.

I asked the question about whether or not the services were saving personal protective equipment (PPE). The response to that question was somewhat mixed. I am not clear on what it means but speculate that some of the staff still need to have direct patient contact at some point during the day. Most acute-care staff at this point have been assigned PPE. The PPE specifics seem to vary from place to place but it is clearly rationed. If I was designing a survey of acute-care psychiatric facilities I would like to see the specifics of how many people had N95 masks and other kinds of protective gear.

Preadmission screening remains a question mark.  There is general agreement that there is an asymptomatic carrier state for SARS-CoV-2 (1,2).  Carriers may have a lower viral load and be partially symptomatic. Most people admitted to inpatient psychiatric units these days require intensive nursing care for their own safety. If there were environments where patients with COVID-19 could be safely segregated and treated that would be ideal, but I doubt those kinds of environments exist on inpatient psychiatric units. Even then the asymptomatic carriers would require the same psychosocial interventions as non-carriers.  The general screening done is to ask about contact with known cases and daily temperatures. I am not aware of any screening procedures that involve trying to identify the virus and carrier state.

My overriding concern is that medical and psychiatric staff everywhere have adequate protection. We have known since my days on the avian influenza task forces that airborne viruses are difficult to contain. They can infect through surface contamination, droplet contamination, and traveling on air currents. Working to cancel all those routes of infection is a tall order especially on an inpatient psychiatric unit.

The only practical way to maintain the level of communication necessary and minimize risk of infection is through some type of electronic communication. Some of the early methods have been listed in this post. Having worked in these settings for a large part of my adult life I am very concerned about the staff with daily direct patient contact including nursing, nursing assistants, and occupational therapy.  Housekeeping staff also have a vital role and are directly exposed to most contaminated surfaces. I have seen large numbers of inpatient staff come down with seasonal respiratory viruses and I know that vulnerability is there. They all need PPE. We need additional innovation in these settings to protect all staff and patients.  

And we have needed that innovation for a long time.

George Dawson, MD, DFAPA




References:


1: Lai CC, Liu YH, Wang CY, Wang YH, Hsueh SC, Yen MY, Ko WC, Hsueh PR. Asymptomatic carrier state, acute respiratory disease, and pneumonia due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2): Facts and myths. J Microbiol Immunol Infect. 2020 Mar 4. pii: S1684-1182(20)30040-2. doi: 10.1016/j.jmii.2020.02.012. [Epub ahead of print] Review. PubMed PMID: 32173241.

2: 1: Hu Z, Song C, Xu C, Jin G, Chen Y, Xu X, Ma H, Chen W, Lin Y, Zheng Y, Wang J,Hu Z, Yi Y, Shen H. Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing, China. Sci China Life Sci. 2020 Mar 4. doi: 10.1007/s11427-020-1661-4. [Epub ahead of print] PubMed PMID: 32146694.

Supplementary 1:

I am very interested in what you are doing at your facility to contain this virus while continuing to go to work every day and treat patients.  I am also very interested in whether you have enough PPE.  I am interested in hearing from everybody staff psychiatrists, residents, social workers, occupational therapists, nurses, nursing assistants, and housekeeping staff.  Please post in the comments section below and feel free to remain anonymous. 


Graphic Credit:

Shutterstock per their standard agreement.