Pandemic Challenge

Sars-CoV-2 (COVID-19) Eugene C. Cole, DrPH

Pandemic Challenge

“The single biggest threat to man’s continued dominance on the planet is a virus”

Joshua Lederberg Molecular Biologist & Nobel Laureate

Viruses A virus is a microscopic parasite

that infects a living cell of a host, and directs the cell’s machinery to produce more viruses.

As that process continues, damage to the host occurs, as manifested by symptoms and adverse health effects.

Viruses consist of a nucleic acid core (DNA or RNA) surrounded by a protective protein coat (capsid). Some have an envelope, which is a lipid bilayer that surrounds the core and capsid.

Infection v. Disease

Infection is invasion of the body by microorganisms that have the capability to cause disease (pathogen).

If an infectious agent maintains itself in the body without producing host damage, it is termed colonization or latent infection.

Disease results when a colonized pathogen overcomes host defenses and utilizes host tissue, producing a pathology (adverse changes in body function) in the host. Such changes are eventually manifest as recognized “symptoms”.

Global Plagues

Epidemics and pandemics have affected mankind for thousands of years, and will continue to do so.

Billions of people have been infected, and millions have died from pandemic diseases such as polio, smallpox, cholera, influenza and HIV.

Typically, pandemic pathogens come from animal reservoirs.

All Influenza viruses originate in birds.

Coronaviruses are found mainly in a variety of mammals.

Pandemic

A pandemic is the spread of an infectious disease through sustained human-to-human transmission in 2 or more countries in one WHO Region, and at least one other country in another WHO Region.

Pandemic Phases Epidemic and Pandemic Alert

and Response (EPR)

Pandemic Continuum

COVID-19

Biology

Enveloped (+) ssRNA virus, 60-120 nm dia

Very efficient at replication inside human lung epithelium cells to produce mild to severe respiratory disease.

Genetically it is closely related to the SARS-CoV virus of the 2003 epidemic, and almost identical to some animal coronaviruses.

Structurally, it has a lipid envelope that is not protective, but renders the virus very susceptible to detergents, sanitizers, and disinfectants.

COVID-19

Pathology

Incubation Period 2-7 days or longer.

Infects lung epithelium cells in alveolar region.

Symptoms include fever (85-90%), dry cough (65-70%), fatigue (35-40%) sputum production (30-35%), shortness of breath (15-20%), and nasal congestion.

Illness may progress to severe disease (ARDS) with extreme shortness of breath and severe chest symptoms - with severe pneumonia in ~75% of patients in the 2nd or 3rd week.

COVID-19

Pathology

Some infected individuals may remain asymptomatic (show no symptoms) and never progress to disease.

Without wide-spread testing of millions of people, there’s no knowledge of what percentage of infected persons never show symptoms.

Some infected individuals may only show very mild symptoms, seek no help, and recover.

With both groups, there is presently no data to suggest how many of these persons may transmit the virus to others.

COVID-19

Treatment

Other than supportive therapy, the following are being used to treat many cases.

Remdesivir is a potential drug for treatment of COVID-19. It is a broad-spectrum antiviral with laboratory and anecdotal reports of effectiveness.

Hydroxychloroquine is reported effective in treating severely diseased COVID-19 patients in Europe and the US, and has approval of the FDA.

Convalescent serum - pre-formed antibodies to COVID-19 from surviving patients is also being used with success.

COVID-19

Infectivity

Factors Required for Infectivity:

Infective Dose (concentration) of the virus needed to initiate the infection/disease process.

Virulence of the virus - genetically based, disease-promoting factors that enable it to overcome normal defenses of the body.

Immune Status of the host (susceptibility) - low, weak, or non-existent immune function (due to immunodeficiency disease, or immunosuppression as a result of chemotherapy, transplantation, pregnancy, or lack of appropriate and available vaccination).

COVID-19

Infectivity

Susceptibility includes older age, being male, especially those >65, those who are immunocompromised, living in nursing homes or LTCFs, and those with high risk conditions: chronic lung disease, moderate to severe asthma, serious heart conditions, and poorly controlled diabetes, renal failure, liver disease.

Pregnant women are considered at increased risk due to lowered immune function. There is no evidence of vertical transmission to the fetus.

COVID-19

Infectivity

It is the 7th member of the Coronaviridae family to cause human disease, along with SARS-CoV (2003 epidemic), and MERS (2012) outbreak.

Moderately to highly infectious

Via respiratory droplets and other close contact with infected persons.

Via contaminated surfaces and materials (fomite contact).

Its reproductive number (R0) is ~2.0-3.0; indicating that each infected person will transmit the virus to at least 2 or 3 other people.

COVID-19

Infectivity

Viral aerosols (droplets) usually consist of a mixture of aggregate viruses, and few mono-dispersed (single) viruses, carried by other materials, such as respiratory secretions and/or inert particles.

Aerosol size changes as they are aerosolized and exposed to environmental factors (RH, temperature) that favor desiccation or hygroscopicity.

COVID-19

Infectivity

Thus a sneeze can generate as many as 40,000 droplets, most of which can evaporate to particles in the 0.5 to 12 µm range (droplet nuclei).

These can deposited in the upper respiratory region or on commonly touched surfaces to be transmitted by contact.

COVID-19

Infectivity

Fomite transmission is just as significant as with aerosols, as people touch surfaces and then their faces, with viral inoculation of the eyes, nose, or mouth.

Surface contamination with viruses protected in a protein matrix, becomes challenging in regard to the need for effective cleaning products and practices.

COVID-19

Epidemiology

Recent gene-mapping research indicates that a spike mutation occurred in the virus in November 2019, and triggered the jump to humans.

Sustained human to human transmission occurred in China in December 2019, and then spread rapidly.

COVID-19

Epidemiology

Current evidence suggests it likely crossed to humans from bat and pangolin reservoirs.

COVID-19

Epidemiology

Evidence shows likelihood of bats infecting pangolins, which are in demand in Asia. Their meat is a delicacy, and there are perceived medical benefits associated with pangolin scales.

Major Influenza Pandemics

1918 – “Spanish flu” Influenza A(H1N1)

Killed more than 50 million worldwide; ~675,000 in U.S.

1957 – “Asian flu” Influenza A(H2N2)

Killed 1.1 million world-wide; 116,000 in U.S.

1968 – “Hong Kong flu” Influenza A(H3N2)

Killed 1 million world-wide; 100,000 died in U.S.

"Emergency hospital during 1918

influenza epidemic, Camp Funston,

Kansas"

Courtesy of the National Museum of Health and

Medicine, Armed Forces Institute of Pathology,

Washington, D.C., Image NCP 1603

H1N1 Pandemic 2009

A type A strain (H1N1) of the influenza virus, “swine flu” believed to have started in a young boy in close contact with pigs in rural Mexico.

In the initial phase of the pandemic, most of the US children who died were at least 5 years of age, and 67% had high-risk medical conditions.

16,000 confirmed deaths globally.

USA Flu Pandemic

2017-2018

Influenza A virus (H3N2)

Burden of Illness

>45 million infected

>810,000 hospitalizations

>61,000 deaths

Case fatality rate = 1.3%

Control Factors

Self-quarantine/treatment

Some cross-immunity from

previous infections and

current flu vaccine

SARS-CoV Epidemic 2003

Emerged in Asia in China in February 2003, spreading to more than 30 countries in North America, South America, Europe, and Asia.

Newly recognized coronavirus.

Flu–like symptoms/pneumonia.

>8,400 cases, >900 deaths, (CFR=15%)

High risk to health workers

CFR=21%

Supportive treatment only.

Wild animal reservoirs (palm civet).

Development of a SARS vaccine in the years since, have been unsuccessful.

MERS Epidemic 2012

Middle East epi-center

Transmission by close contact; agent was identified as a new coronavirus, called MERS-CoV.

~1,600 cases, mostly in Saudi Arabia (CFR = 35%)

Respiratory symptoms typical of SARS – acute respiratory illness with fever, cough, and shortness of breath.

Primary animal reservoir appears to be camels.

COVID-19

Survival

A 2010 study showed that animal coronaviruses could survive from 5-28 days on hard surfaces, depending upon air temperature and RH.

And a recent 2020 study has confirmed that COVID-19 can survive up to 2-3 days on plastic and stainless steel, 4 hours on copper, and up to 24 hours on cardboard.

While studies on coronavirus survival on fabric are scant, data show survival on cotton cloth for only one hour.

COVID-19 Control

Transmission in the home: If available and tolerable, the patient

should wear a disposable mask when sharing common spaces with others, especially those at-risk for COVID-19.

It is important to treat surfaces (especially bedside tables, surfaces in the bathroom, kitchen counters and desks, etc.) by cleaning with a detergent solution and then applying a household disinfectant according to directions on the product label.

COVID-19 Control

Transmission in the home:

Frequent hand washing will reduce coronaviruses on the hands by removal and inactivation.

When hand washing isn’t practical, and when hands are not visibly soiled, the use of hand sanitizer is effective against enveloped viruses, providing alcohol (ethanol or isopropanol) concentration is at least 62%.

COVID-19 Remediation

Protecting Custodial Workers Understand infectious agent and transmission.

Identify key contact points: desktops, table tops, countertops, drawer and cabinet pulls, appliance handles, copy machines, elevator buttons, door handles and knobs, water coolers and fountains.

Use personal protective equipment (PPE) as required: disposable gloves, masks, coveralls will minimize transport of contamination to the home.

Clean surfaces with EPA-approved disinfectant cleaner products with coronavirus or emerging pathogen claims.

COVID-19 Remediation

Protecting Custodial Workers Use trigger spray cleaner, allowing proper dwell time,

and hand clean with suitable cloth or towel.

Close off areas where high risk incidents have occurred, such as vomiting or bleeding, and report them to management for proper hazard remediation.

Ensure that cleaning equipment is maintained and cleaned properly to prevent spread of contamination.

Engage in frequent handwashing, and do not store or eat food in janitorial rooms or closets.

Notify management immediately if symptoms of illness are noticed.

COVID-19 Remediation

Cleaning Cleaning is a systematic, science-based process of

managing unwanted matter, so human activities can take place in a healthy environment.

For schools in particular, recent studies have collectively indicated that enhanced hygiene in schools, with targeted cleaning of biological residual contamination related to frequent contact points, resulted in reduced illnesses tied to bacterial contamination reservoirs, reduced sick building syndromes, and reduced absenteeism due to infectious illnesses.

References

Velavan TP, Meyer CG (2020). The COVID-19 epidemic. Tropical Medicine and International Health, 25(3):278-280.

van Doremalen et al (2020). Aerosol and surface stability of HCoV-19 (SARS-CoV-6 2) compared to SARS-CoV-1. New England Journal of Medicine, Mar 17 [Epub ahead of print]

Casanova LM, Jeon S, Rutala WA, Weber DJ, Sobsey MD (2010). Effects of air temperature and relative humidity on Coronavirus survival on surfaces. Applied and Environmental Microbiology, May, 2712-2717.

Lai MYY, Cheng PKC, Lim WWL (2005). Survival of Severe Acute Respiratory Coronavirus. Clinical Infectious Diseases, 41:e67-71.

References

Cui J, Li F, Shi Z (2019). Origin and evolution of pathogenic coronaviruses. Nature Reviews Microbiology, (17): 181-192.

To KKW, Hung IFN, Chan JFW, Yuen K (2013). From SARS coronavirus to novel animal and human coronaviruses. Journal of Thoracic Disease, 5(S2):S103-S108.

Wang et al (2020). Remdesivir and chloroquine effectively inhibit the recently emerged novel coronavirus (2019-nCoV) in vitro. Cell Research, 30:269-271.

Yin Y, Wunderink G 2018. MERS, SARS and other coronaviruses a causes of pneumonia. Respirology, 23:130-137.

Eugene C. Cole, DrPH

Research Director

LRC Indoor Testing & Research, Cary, NC

Dr. Cole’s applied health research studies have long supported the

cleaning and restoration industries. His focus includes indoor

microbial ecology, bioaerosols, and human exposure assessment. A

former Professor of Environmental Health Sciences at Brigham

Young University, Dr. Cole holds both a Master of Science degree

in Public Health Microbiology, and a Doctor of Public Health

degree in Biohazard Science & Occupational Health from the

University of North Carolina at Chapel Hill. He is a member of the

Science Advisory Council of the Cleaning Industry Research

Institute (CIRI) and a Fellow of the American Industrial Hygiene

Association (AIHA).