COVID-19: The Airborne Division

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More than 3 months after the novel coronavirus was first announced in Wuhan City, there is still sharp division among scientists whether SAR-CoV-2 - the virus that causes COVID-19 - is an `airborne' pathogen, or is spread primarily by large droplets.

This makes a huge practical difference, because the WHO - which subscribes to the `droplet' theory - only recommends `contact and droplet precautions' (gloves, gown, surgical mask & eye protection) for HCWs dealing with COVID-19 patients. 

Many other scientists, however, aren't so certain. And getting this wrong, and recommending the wrong type of PPEs, could cost lives.  In the United States, the CDC preferentially recommends N95s (when available), but due to shortages has proposed an `acceptable alternative'.




You can read about the current scientific debate over the airborne spread of COVID-19  in the following  April 2nd article in Nature:

02 APRIL 2020

Is the coronavirus airborne? Experts can’t agree

The World Health Organization says the evidence is not compelling, but scientists warn that gathering sufficient data could take years and cost lives.

We all want evidence-based medicine and public health policies, but sometimes, the evidence is either scant or slow in coming.  And for reasons that escape me, many officials seem to assume a threat is benign, until proven otherwise. 

Lest we forget, it wasn't until January 18th - nearly 3 weeks after the Wuhan pneumonia outbreak became known outside of China - that the WHO finally reversed their `No evidence of Human-to-Human Transmission' mantra. 

World Health Organization Western Pacific

@WHOWPRO ·16m

According to the latest information received and @WHO analysis, there is evidence of limited human-to-human transmission of #nCOV. This is in line with experience with other respiratory illnesses and in particular with other coronavirus outbreaks.

World Health Organization Western Pacific@WHOWPRO·16m

While there is currently no clear evidence of sustained human-to-human transmission, we do not have enough evidence to evaluate the full extent of human-to-human transmission. This is one of the issues that @WHO is monitoring closely.

By that time, I think most of us had assumed H-2-H transmission was occuring, but even then the WHO was downplaying `sustained' transmission potential based on a lack of `clear evidence'.  

Obviously, China had to know it was sustained and efficient by then, but that's a rant for another day . . . 

I'm not a scientist, but as a paramedic, if I came across a car wreck with a downed electrical wire draped across the vehicle, I'm going to assume it is `hot' until proven otherwise.

I'll leave the definitive `two wet finger test' for someone else to perform. 

This need for `clear evidence' or scientific certainty before making a decision or acting decisively isn't always practical in the real world, where weighing the evidence for days, weeks, or months can cost lives.

In 2014, two Texas nurses fell ill after treating an imported Ebola case, sparking a heated debate over the quality of both their PPEs and their safety training (see Nurses Claim Lack Of Safety Protocols For Dealing With Ebola). 

At the time, the CDC's recommendations for HCWs dealing with a suspected or confirmed Ebola case included contact (gloves, gown) and droplet protection (surgical masks, eye protection), but full skin covering and the use of respirators (ie. PAPR, N95) were not advised for patient care not involving aerosol generating procedures (AGPs).

Five days later the CDC issued Stricter PPE Recommendations For Ebola, including:

• No exposed skin

• N95 or PAPR instead of surgical or facemask

• Use of virocidal wipes on exterior of PPEs before doffing

Additionally, Dr. Frieden stated that HCWs would need enhanced training in the donning and doffing of PPEs, and facilities should appoint someone to act as a full time site supervisor to monitor and assist in PPE use and removal when treating an Ebola patient.

The sound `scientific evidence' on October 15th was found wanting by the 20th.  Looking back, it's hard to believe that surgical masks were ever deemed appropriate for Ebola.

While some may argue there isn't 100% proof that COVID-19 is airborne, or clear evidence that N95s would offer substantially superior protection to HCWs, it is hard not to assume the real reason behind the surgical mask recommendation is the global shortage of anything better.

Most HCWs realize this - and while feeling betrayed by this lack of preparedness - will probably soldier on with whatever PPEs they have. But by hiding behind this `lack of clear evidence' excuse, officials are only adding insult to potential injury.  

The CDC's Cloth Face Cover Recommendations

How to Wear Face Cover

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As we discussed yesterday in Masking Our COVID-19 Concerns, there has been a growing call for Americans to wear some sort mask in public during the pandemic, if for no other reason than to prevent asymptomatic carriers from spreading the virus.  

After much debate, late yesterday the CDC issued `Face Cover' recommendations for the general public, along with some easy tutorials (below) on how to make these items at home. 

Although a homemade face cover probably provides very limited protection to the wearer, it can reduce the transmission of the virus to others and it can remind us not to touch our face. They are not a substitute, however, for social distancing (staying 6 feet apart), handwashing, or staying home as much as possible.

While a imperfect solution, as part of a layered, NPI approach, they can help reduce community transmission of the virus. If nothing else, by wearing one, you are showing respect for the health and welfare of others, and are setting a good example at the same time.

Use of Cloth Face Coverings to Help Slow the Spread of COVID-19

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Face coverings should—

• fit snugly but comfortably against the side of the face

• be secured with ties or ear loops

• include multiple layers of fabric

• allow for breathing without restriction

• be able to be laundered and machine dried without damage or change to shape

CDC on Homemade Face Covers

CDC recommends wearing cloth face coverings in public settings where other social distancing measures are difficult to maintain (e.g., grocery stores and pharmacies), especially in areas of significant community-based transmission.

CDC also advises the use of simple cloth face coverings to slow the spread of the virus and help people who may have the virus and do not know it from transmitting it to others. Cloth face coverings fashioned from household items or made at home from common materials at low cost can be used as an additional, voluntary public health measure.

Cloth face coverings should not be placed on young children under age 2, anyone who has trouble breathing, or is unconscious, incapacitated or otherwise unable to remove the mask without assistance.

The cloth face coverings recommended are not surgical masks or N-95 respirators. Those are critical supplies that must continue to be reserved for healthcare workers and other medical first responders, as recommended by current CDC guidance.

Should cloth face coverings be washed or otherwise cleaned regularly? How regularly?

Yes. They should be routinely washed depending on the frequency of use. 

How does one safely sterilize/clean a cloth face cover?

A washing machine should suffice in properly washing a face covering. 

How does one safely remove a used face cover?

Individuals should be careful not to touch their eyes, nose, and mouth when removing their face covering and wash hands immediately after removing.

Masking Our COVID-19 Concerns

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In late January, in The Man In The Ironed Mask (Revisited), I wrote about the all-but inevitable shortages of PPEs (personal protective equipment) from the looming coronavirus pandemic, and discussed in some depth the research that had been done on homemade, cloth face masks and even provided a link to how to make one. 

While studies (see A cluster randomised trial of cloth masks compared with medical masks in healthcare workers) have shown them to be a poor substitute for disposable PPEs, they are - quite literally - better than nothing. 

Even the CDC agrees - at least for Heath Care workers without access to proper PPEs, as their March 17th Strategies for Optimizing the Supply of Facemasks even allows:

HCP use of homemade masks:

In settings where facemasks are not available, HCP might use homemade masks (e.g., bandana, scarf) for care of patients with COVID-19 as a last resort. However, homemade masks are not considered PPE, since their capability to protect HCP is unknown. Caution should be exercised when considering this option. Homemade masks should ideally be used in combination with a face shield that covers the entire front (that extends to the chin or below) and sides of the face.

The debate over the public wearing of masks continues, and has not yet officially been recommended by the WHO, or the CDC. Frankly, the mixed, and convoluted messaging over why the public shouldn't wear masks (they don't protect against the virus, and should be reserved for HCWs who need them) has diminished their credibility. 

The `right' message should have been, we don't have enough disposable PPEs for HCWs, so please make your own masks, and wear them in public, along with washing your hands, social distancing, and the rest of the the standard advice. 

Simple, honest, and most people would have accepted the reality.  

Although I don't understand why it has taken two months, in recent days the opinion and advice appears to be changing, as yesterday and overnight we've seen headlines such as:

Los Angeles mayor urges everyone to wear masks

Wearing Masks Must Be a National Policy - NYTs

Every American should wear a face mask to defeat Covid-19 - STAT

Those Asian countries (Singapore, Taiwan, Japan, etc.) that encourage the wearing of masks in public are seeing far fewer community cases of COVID-19 than countries that have discouraged the practice.  Whether this is due to some degree of protection for the wearer, or to a reduction of virus transmission by infected individuals, the end result is the same.

Masks can help reduce the transmission of the virus.  They are far from perfect, but as part of a layered NPI approach (hand washing, social distancing, avoiding touching your face, etc.) they can help reduce the spread of the disease. 

I previously wrote:

While cloth masks from places like Amazon are on backorder, anyone who is handy with a sewing machine can find dozens of tutorials on YouTube on how to make cloth face masks, and I've even seen some `glue gun specials', which don't require sewing skills.

With so many people stuck at home, unable to work, this could be a terrific local cottage industry for a lot of people. To either sell (or better yet) to donate to friends and neighbors.

Although I possess zero sewing skills, and don't own a sewing machine, I managed to cobble together a serviceable face mask yesterday at home, using an old pillow case, some thin elastic bands, and a glue gun in about 20 minutes.

The photo at the top is the front of the mask, you can see the reverse below:

I even glued a metallic nose strip using a piece from an old, used N95.  A stiff piece of wire would probably have worked as well.  It admittedly isn't pretty, but I expect version 2.0 will be slightly better. 

The point is, if I can make one, you can make one.  

And since COVID-19 is likely to be with us for some time to come, and the public wearing of masks may soon become de rigueur, you might want to try your hand at making some yourself.

Italy: 4,668 New COVID-19 Cases, 760 Deaths

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Today's numbers from Italy - while still high - are slightly lower than yesterday's report, and offer further evidence that three weeks of lockdown and social distancing are having an effect. The official numbers (115,242 cases and 13,915 deaths) are undoubtedly massive undercounts, however.

Many mild or moderate infections have not been counted, which would drive Italy's apparent CFR (Case Fatality Rate) of roughly 12% far lower, but at the same time, an unknown number of COVID-19 deaths have gone uncounted as well.

A story in today's Wall Street Journal (Italy’s Coronavirus Death Toll Is Far Higher Than Reported) illustrates the problems in counting COVID-19 - or any other infectious disease outbreak - fatalities. This is a topic we've looked at many times before (see Lancet: Estimating Global 2009 Pandemic Mortality).


While it is highly unlikely that Italy's CFR is anywhere near what the official numbers suggest, without a reasonable denominator (ttl number of cases) and an unknown numerator (number of deaths), we are left guessing. 

While Italy has managed to flatten their curve, how long it will take to get the number of new infections low enough to allow for a relaxation of their strict social distancing measures, and restart their economy, is still a big unknown.

From today's update:

The situation in Italy: April 2, 2020, 6.00 p.m.

CURRENTLY POSITIVE    83049
DECEASED                          13915
HEALED                               18278


Press conference at 6 pm on April 2nd

115,242 total cases, currently positive people are 83,049, 13,915 died and 18,278 recovered.

Among the 83,049 positives:

• 50,456 are in home isolation

• 28,540 hospitalized with symptoms

• 4,053 in intensive care

Read the tables

• Italy situation on April 2nd
• Breakdown by provinces on April 2

Consult the map

• Situation in Italy - desktop version
• Situation in Italy - mobile version

Standards Of Care During A Pandemic: CPR & Cardiac Arrest

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One of the realities of life during a pandemic is that the standards of care normally afforded in our society to people in medical distress can change - even for those who are not infected with the virus.  Hospitals are going to be overwhelmed, ICU beds will be in short supply, and hospital staff and 1st responders are going to be overworked and spread very thin.

To put it bluntly, this is a very bad time to have a heart attack, get into a car accident, need dialysis or cancer treatment, or suffer any sort of acute medical emergency. 

Previously we've looked at standards of care concerns in:

JAMA: A Framework for Rationing Ventilators & ICU Beds During the COVID-19 Pandemic

HHS ASPR-TRACIE: COVID-19 Crisis Standards of Care Resources

Contemplating A Different `Standard of Care'

Yesterday, multiple media outlets in New York City reported that local EMS will no longer `work' a cardiac arrest on the way to the hospital.  If an adult cardiac arrest patient cannot be revived on the scene, they will be pronounced dead by the EMS team, and a mortuary removal service will transport the body.

This report from NYC PIX II:

New EMT directive limits some hospital transports as NYC hospitals fill with COVID-19 patients

Posted: 5:39 AM, Apr 02, 2020

Unlike on TV and in the movies, most unwitnessed, out-of-hospital cardiac arrests don't survive.  And many of those that are `revived' initially end up dying hours or days later.  Even inside a hospital, a good outcome following a cardiac arrest is far from guaranteed. 

With hospital Emergency Departments clogged with the sick, the injured, and the worried well - there simply aren't enough resources available to devote to what is probably a lost cause.   

And if the cardiac arrest patient is infected with the virus, doing a full `code' on them at the hospital will likely aerosolize their virus and could infect many others.  Not only would a large portion of the Emergency Department become contaminated, so would the EMS rig that transported the patient, which would take both out of service for decontamination.

Recently, the American Heart Association released new guidelines on doing CPR and resuscitation of suspected or known COVID-19 patients. Similar concerns were raised in the following  BMJ (British Medical Journal) report published late last week:

Covid-19: Doctors are told not to perform CPR on patients in cardiac arrest
BMJ 2020; 368 doi: https://doi.org/10.1136/bmj.m1282 (Published 29 March 2020)

Elisabeth Mahase, Zosia KmietowiczAuthor affiliations

Healthcare staff in the West Midlands have been told not to start chest compressions or ventilation in patients who are in cardiac arrest if they have suspected or diagnosed covid-19 unless they are in the emergency department and staff are wearing full personal protective equipment (PPE).

The guidance from the University Hospitals Birmingham NHS Foundation Trust says that patients in cardiac arrest outside the emergency department can be given defibrillator treatment if they have a “shockable” rhythm. But if this fails to restart the heart “further resuscitation is futile,” it says.

(Continue . . . )

Despite the risks and the low probability of success, I personally would not hesitate to do CPR on a loved one in cardiac arrest, but I would probably opt for a `safer' procedure, such as depicted in the graphic below. First, calling for help, then doing compressions only, while placing some kind of cloth barrier lightly over the nose and mouth of the victim. 

During a pandemic, our standards of care will inevitably decline, particularly for some critically ill patients. We can take some solace from the fact that even had they been afforded full medical interventions, many would not have survived.

But the reality is, some salvageable patients will be lost to this pandemic - not because they were infected with the virus - but because of the pandemic's strain on our healthcare system. 

Susceptibility of Ferrets, Cats, Dogs & Other Domestic Animals to SARS-CoV-2

The Undisputed Queen of My Household

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Five weeks ago, in Hong Kong AFCD: Dog Tests `Weakly Positive' For COVID-19, we saw the first report of a companion animal infected with the novel coronavirus.   Since then, Hong Kong has reported a second dog has been infected, and two days ago announced a Pet cat tested positive for COVID-19 virus.

In all of these cases, the assumption is that these animals contracted the virus from exposure to their already infected human companions; reverse zoonosis. 

During the H1N1 pandemic of 2009 we saw both dogs (see US: Dog Tests Positive For H1N1) and cats (see Companion Animals And Novel H1N1) infected with the virus. Given that SARS-CoV-2  appears to have originated in a mammal (bats), and has jumped species - probably at least twice - it  is not terribly surprising that exposed companion animals might be susceptible to infection as well.

There is currently no evidence that companion animals can - or have - transmitted the virus to humans, and with the number of confirmed human cases expected to exceed 1 million today (and the real number likely many times higher), you are far more likely to be infected by another person than by your pet.  

But of course, it is valuable to know which animals species are susceptible to the virus, whether it sickens them, and whether they shed the virus enough to be infectious.  

It would be very important if we discovered that the virus favored pigs, chickens, or other livestock - as those populations might promote additional viral mammalian adaptation, and continually reseed the virus into humans.

Enter Dr. Hualan Chen - one of the world's most respected virologists - and director of China's National Avian Influenza Reference Laboratory, whose work we've followed for years in this blog (see here, here and here), and who has conducted research on the susceptibility of a variety of animals to the SARS-CoV-2, the virus that causes COVID-19 in humans.

Despite its excellent pedigree, this study is on a preprint server (BioRxiv), and has not been peer reviewed, and should be viewed in that light.  First the link, and the abstract, then a brief look at a Nature article published yesterday on these findings.

Susceptibility of ferrets, cats, dogs, and different domestic animals to SARS-coronavirus-2

Hualan Chen et al.

doi: https://doi.org/10.1101/2020.03.30.015347

This article is a preprint and has not been certified by peer review [what does this mean?].

Preview PDF
Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the infectious disease COVID-19, which was first reported in Wuhan, China in December, 2019. Despite the tremendous efforts to control the disease, COVID-19 has now spread to over 100 countries and caused a global pandemic. 

SARS-CoV-2 is thought to have originated in bats; however, the intermediate animal sources of the virus are completely unknown. Here, we investigated the susceptibility of ferrets and animals in close contact with humans to SARS-CoV-2.

We found that SARS-CoV-2 replicates poorly in dogs, pigs, chickens, and ducks, but efficiently in ferrets and cats. We found that the virus transmits in cats via respiratory droplets. Our study provides important insights into the animal reservoirs of SARS-CoV-2 and animal management for COVID-19 control.

(Continue . . . )

A less technical overview can be found in this article in Nature:

Coronavirus can infect cats — dogs, not so much

But scientists say it’s unclear whether felines can spread the virus to people, so pet owners need not panic yet.

The good news is this virus doesn't have a great affinity for pigs, chickens, or ducks and only weakly infects dogs.  The replication reported in ferrets is hardly surprising, given that SARS-CoV-2 is a respiratory virus that is well adapted to humans.  

The implications of it replicating, and transmitting (albeit rather poorly in this study), in cats, will require further investigation. Cat-to-human transmission of a novel respiratory virus is rare, but has been reported (see EID Journal: Avian H7N2 Virus in Human Exposed to Sick Cats).

Another species I would have like to have seen included in this study are mink. They are extensively farmed in China - and around the world - and like ferrets, are highly susceptible to a number of human viral respiratory infections. A few of many studies we've looked at include:

Vet. MicroB.: Eurasian Avian-Like Swine Influenza A (H1N1) Virus from Mink in China

Nature: Semiaquatic Mammals As Intermediate Hosts For Avian InfluenzaThat Touch Of Mink Flu (H9N2 Edition)

I imagine there are also studies looking into the susceptibility of dromedary camels and other camelid species to this virus, as they are already known to be susceptible to MERS-CoV.  And of course, the (presumed) intermediate host species that likely transmitted the virus to humans has yet to be identified.

While it seems a lifetime ago, we are barely 3 months since the world (outside of Mainland China) became aware of this novel coronavirus, and so research is scarce. It took nearly a year for researchers to prove a connection between MERS-CoV infection in humans and camel exposure (see Camels Found With Antibodies To MERS-CoV-Like Virus).

All of which means there are probably a few surprises with SARS-CoV-2 still ahead.