We Cannot Let This Happen Again!

COVID-19: A Path to Death and Destruction

Mary C. Vrtis, Ph.D., MSN, RN, OCN, NEA-BC, FCN

China – December 2019 to February 2020

On December 29, 2019, clinical staff at a local hospital in Wuhan City, located in the Hubei Province of China, admitted four patients with pneumonia due to a novel coronavirus infection. Local municipal and provincial investigations linked all four patients to the Huanan Seafood Wholesale Market in Wuhan. This market sold seafood, live poultry, and wild animals The national China Center for Control and Prevention was notified on December 29 and a field investigation began (China CDC January 31, 2020; Li, et al., 2020).

China was able to identify the emergence of the new virus and respond quickly because the country has a national sentinel surveillance system designed to rapidly identify outbreaks of severe acute respiratory illnesses and influenza. The surveillance was initiated following the outbreak of the first severe acute respiratory syndrome (SARS) that spread rapidly in China in 2003. That outbreak was caused by a different novel coronavirus then named SARS-CoV. Hospitals, healthcare personnel, and laboratories are required to report possible cases and submit relevant laboratory data that is then processed through the China Center for Disease Control and Prevention. At the time, Wuhan City had a population of 11.1 million and Hubei Province 59 million people (WHO, February 2021).

On December 31, 2019, China notified the World Health Organization (WHO) through the World Health Organization China Country Office that a cluster of patients with pneumonia of unknown etiology were identified. As of January 3, 2020, the outbreak involved 44 patients in Wuhan City. At that time, the source of infection was not known (World Health Organization, Jan. 21, 2020).

Field investigations by the national China CDC and local China CDC branches identified 47 patients who were infected before December 31, 2019. Twenty-six of those patients (55%) had contact with the same market, and an additional four had contact with another market that sold similar products. Thirty percent (14 people) had contact with someone who had respiratory symptoms, and 12 confirmed patients had no known exposure to anyone who was ill (Li, et al., 2020).

The virus that causes COVID-19 was named by the World Health Organization severe acute respiratory syndrome coronavirus 2, also known as SARS-CoV-2, in February of 2020. It is a pathogenic coronavirus (abbreviated CoV), part of the family of coronaviruses that includes viruses that cause respiratory infections that range in severity from the common cold to severe, acute respiratory syndromes (SARS). The new virus was deemed (CoV-2) because it was a new, previously unknown genome.  

The disease caused by SARS-CoV-2 was named COVID-19 by the World Health Organization on February 11, 2020. CO stands for coronavirus, VI stands for virus, and D stands for disease. The -19 is because the disease was identified in 2019 (WHO, n.d.)

Advanced Technologies, Genetic Sequencing and Global Sharing of Scientific Information

By January 3, 2020, the novel virus had been isolated from respiratory samples obtained from one hospitalized patient in Wuhan. It was identified as a coronavirus most closely related to a type found in bats. Genetic sequencing was performed, and three distinct strains of the virus were obtained from one patient (the virus had already started to mutate). The first three genome sequences were uploaded to gisaid.org with submission numbers EPI_ISL_402119, EPI_ISL_ 402020 and EPI_ISL_402121 (Tan, et al., 2020).

Deadly Mutations: Probable Zoonotic Origin of SARS-CoV-2

Although the viral genome had been sequenced, little was known about the evolution of SARS-CoV-2 or the source of the infecting organism. Early on, the working hypothesis was that COVID-19 was a novel virus that emerged from a genetic mutation of a coronavirus that was present in an animal (zoonotic) host. The mutated virus reproduced in some type of host animal, and the most likely candidate was a bat given how close the COVID-19 genome is to a specific coronavirus found in bats. Viral mutation within the host animal resulted in a novel variant or strain that was pathogenic to humans, highly contagious from human to human. Human beings had no protective immunity against this novel virus, see figure 1 (Cohen, 2023; Tan, et al., 2023).

Why Did the Virus Spread So Fast?

The COVID-19 pandemic burned through the human population like wildfire and healthcare providers did not have time in advance to prepare. Because this was a new, novel virus, nurses and other healthcare workers were experiencing the need to take care of seriously ill patients before they were educated on precautions and how to perform safe care. As new variants of concern continue to emerge, ongoing study of the impact of these mutations on the human and animal populations will be necessary for many years to come. As we will discuss later, each new variant that arrives on our doorstep and becomes dominant has some form of competitive advantage over the older dominant variant(s). The newer variant may or may not have a more detrimental effect on the human population.

As shown in figure 1, it is not known how the SARS-CoV-2 virus mutated, making it capable of “jumping” from an animal source to human beings. The first human infection may have been due to touching a contaminated surface, food, bat guano or some other yet unknown contaminant. A human may have been infected directly by handling or eating meat from a sick animal, or the virus could have been transferred from a yet unknown intermediate reservoir animal who was infected from the source animal. Most patients exhibited mild disease and severity ranged from totally asymptomatic (patients tested positive for virus but were not sick) to life-threatening critical illness and death. Factors that were predictive of the impending worldwide disaster were:

  • The SARS-CoV2 virus was highly contagious and spread rapidly from person to person.
  • Humans had NO IMMUNITY as no one had ever been exposed to the newly mutated, novel form of coronavirus.
  • SARS-CoV-2 mutates frequently, and some of the emerging variants were even more capable of causing significant harm (virulence) to the host.
  • Infected patients are able to transmit the infection for several days before symptoms are present, even if totally asymptomatic.

Extensive contact tracing with the first patients who contracted a COVID-19 infection was conducted in China. Between January 1 and January 11, 2020, another 248 patients were diagnosed with COVID-19. For 141 of the new patients, there was no known exposure to anyone who was ill. Of the additional 130 patients identified by January 22, 2020, 59 (73%) had not been exposed to anyone who was ill – suggesting that asymptomatic transmission was likely (Li, et al., 2020).

The researchers identified that most patients who sought medical attention did so within two days of onset of symptoms. Hospitalizations were generally not needed until at least the 5th day of illness for 89% of patients. The authors suggested a 14-day quarantine period with medical observation, but at the time that was only a best estimate based on rapidly emerging data. As of January 22, 2020, the numbers of cases were doubling every 7.2 days (Li, et al, 2020). 

By January 21, 2020, four patients with COVID-19 infections were diagnosed in other countries, Thailand (2), Japan (1), Republic of Korea (1) – these were the first known cases to be identified outside of China, and the infection was acquired during travel (WHO, 2020 January 21). As the infection spread rapidly through the highly mobile human population it was apparent to China and the World Health Organization that this was going to be a global public health emergency. On January 21, 2020, the virus had already spread to other parts of China and had reached three other countries via individuals who traveled by air, most likely before knowing they were ill (World Health Organization, 2020, January 21). The World Health Organization began publishing daily situation reports. By January 31, the infection was in 106 countries, see figure 2 (World Health Organization, 2020 January 31).

Seven days later, on January 28, 2020, the virus had spread through China and there were individuals who tested positive for SARS-CoV-2 in a total of 56 countries (WHO, 2020 January 28).

Humans Spread the Virus Throughout the World

SARS-CoV-2 proved to be a very capable traveler, spreading rapidly within infected humans from one country to the next via planes, trains, ships, and automobiles, see figure 3. The travel network today is massive and global. The respiratory virus SARS-CoV-2 can be transmitted from human to human during the symptomatic and pre-symptomatic stages, as well as by completely asymptomatic individuals. Therefore, airport and other transportation screening is ineffective. Fever, a marker often used to identify ill persons, is not present in pre-symptomatic and asymptomatic travelers, though by the simple act of breathing, they can pass the virus on. Pre-travel testing identifies individuals carrying the virus at the time of the test but does not identify those who may have been exposed after testing, or those who become ill during their travels. Major airports, train stations, and ports are hubs through which millions of passengers pass on a daily basis (Wilson & Chen, 2020). Exposures to COVID-19 can occur through inhalation of virus containing droplets, or indirectly by touching contaminated surfaces and then the eyes, nose, or mouth. 

Individuals traveling on cruise ships were also vulnerable due to the high volume of people on board a single vessel. The Diamond Princess international cruise ship was carrying 2,666 passengers and 1,045 crew when one passenger became symptomatic and had to disembark in Hong Kong. Ultimately, 19.2% of passengers and crew tested positive for COVID-19. Public health travel restrictions were implemented, and U.S. passengers had to travel back to the states via two chartered aircraft, with federal government supervised quarantine that continued for 14 days (Medley, et al., 2021).

As early as January 2020, there was evidence that showed that asymptomatic (or possibly pre-symptomatic) people were able to pass on the infection to others who then developed symptoms of the disease. COVID-19 was confirmed by PCR (polymerase chain reaction) testing. Chinese scientists published information regarding asymptomatic transmission in The New England Journal of Medicine online on January 29, 2020 (Li, et al., 2020).

Modes of Transmission – SARS-CoV-2 (COVID-19) in 2020

In January of 2020, the CDC sent out an alert that stated that the modes of transmission were under study and recommended use of droplet (6 foot), airborne (during aerosolizing procedures), and contact precautions. The use of N-95 respirators, face shield, gowns, gloves, hand hygiene, and masks for the patient with COVID-19 or under investigation for this disease were recommended (CDC Health Alert Network, 2020 January 17). Updates were regularly provided as new information became available.

COVID-19 can be transmitted from one person to another via at least four modes (ways):

  • Droplets of water containing the virus or bacteria may be inhaled as they are suspended in the air when a patient coughs, sneezes, speaks, yells, sings, laughs, etc. – the droplets are heavy and fall to the ground (CDC, 2021 May 7, Leung, 2021).
  • Airborne fine viral/ bacterial particles may be inhaled from the air during aerosolizing procedures such as inserting an endotracheal tube (CDC, 2021 May 7, Leung, 2021, Stadnytskyi, et al., 2020).
  • Direct (physical) contact may occur when contaminated biological material such as sputum is projected and the organism enters the clinician’s unprotected eyes, nose, or mouth (CDC, 2021 May 7, Leung, 2021).
  • Indirect transmission may occur through physical contact with a contaminated object (fomite), surface, or hands if the infectious organism is subsequently carried to the mouth, nose, or eyes (CDC, 2021 May 7; Leung, 2021; Siegel, et al., 2022 May).

The Situation in China and the World Worsened January 2020

China provided the genetic sequence so that other countries could develop virus specific diagnostic kits for testing by January 12, 2020. Unfortunately, by January 20th, the date of this first World Health Organization situation report, cases of human SARS-CoV-2 had already been found in Thailand, Japan, and Korea.  (WHO, Jan. 21, 2020).

China quarantined the population of Wuhan and neighboring cities as of January 23, 2020 (Li, et al., 2020). Unfortunately, it was already too late to contain the infection.

As shown in figure 3, the COVID-19 virus spread very quickly and by the date of World Health Organization Situation Update – 8, on January 28th, there were 4,593 patients with this new, highly contagious pneumonia identified in at least 15 countries. The World Health Organization reported that the first five U.S. cases were identified by this date (WHO, Jan. 28, 2020). China focused on:

  • Identifying new, active infections using RT-PCR (reverse transcription-polymerase chain reaction) testing of nasopharyngeal and respiratory secretions to detect COVID-19 viral RNA.
  • Mapping of the viral genome using next generation sequencing (NGS).
  • Applying epidemiological contact tracing techniques to locate others who may have been infected.
  • Isolating patients with COVID-19 in designated hospitals.
  • Providing information to scientists across the globe.

The goal was to contain the infection by quickly identifying and quarantining sick individuals and their contacts.

China Published an Epidemiological Study February 2020

A team from China published results of a large epidemiological study in February 2020. The epidemic had spread throughout China despite travel restrictions, quarantines, lockdowns of vast territories, and other actions taken to curtail it. By February 11 there were 72,314 cases identified. Of those, 44,672 were cases where the patient’s diagnosis of COVID-19 was confirmed, 10,567 where the infection was clinically diagnosed, 889 patients who were asymptomatic with presence of viral nucleic acids, and 10,567 where COVID-19 was suspected. Asymptomatic patients accounted for 1.2% of the overall sample of medical records (China CDC Novel Coronavirus Pneumonia Emergency Response Epidemiology Team, 2020, February 21).

Fatalities in China February 2020

Of the 44,672 patients with COVID-19 confirmed by the presence of viral nucleic acid in throat swabs, the fatality rate remained at 2.3%. Of the patients with confirmed COVID-19 infections, 3.8% (1,716) were health workers and the infection had been fatal for five health workers.

Deaths due to COVID-19 infection were highest for those 60 years and older. Of the 8,583 infected patients aged 60 to 69, 30.2% died. Another 30.5% of patients the 3,918 patients aged 70 to 79 years old died as well. There were fewer patients 80 and over, 1,408 and the disease was fatal for 20.3%. Gender also made a difference, though the reasons for this were not identified. Whereas 51.4% (22,981) of infected patients were male, 63.8% of those who died were men. A total of 21,691 (48.6%) of the 44,672 patients with confirmed COVID-19 were women, but only 370 women died compared 653 men (China CDC Novel Coronavirus+ Pneumonia Emergency Response Epidemiology Team, 2020, February 21).

Cases were categorized as mild, severe, or critical. Most patients, 80.9% had mild disease. The disease was considered severe when patients had an oxygen saturation of 93% or less, dyspnea, a respiratory rate of 30 or higher and lung infiltrates. Severe disease was evident for 13.8% of patients with a confirmed COVID-19 diagnosis. To be categorized as critical, patients showed evidence of respiratory failure, septic shock, and/ or multi-organ dysfunction (China CDC Novel Coronavirus Pneumonia Emergency Response Epidemiology Team, 2020, February 21).

Almost half (49%) of the 2,087 patients who were critically ill expired. There were no deaths among patients with mild to severe disease (China CDC Novel Coronavirus Pneumonia Emergency Response Epidemiology Team, 2020, February 21).  The authors concluded that from first identified case on December 31, 2019, to the end of the study period on February 11, 2020, the highly contagious novel coronavirus had spread from one city in China to the entire country. “Moreover, it has achieved such far-reaching effects even in the face of extreme response measures including the complete shutdown and isolation of whole cities, cancellation of Chinese New Year celebrations, prohibition of attendance at school and work, massive mobilization of health and public health personnel as well as military medical units, and rapid construction of entire hospitals” (China CDC Novel Coronavirus Pneumonia Emergency Response Epidemiology Team, 2020, February 21).

U.S. COVID-19 Study – Outcomes in March 2020

During February and March 2020, the number of patients diagnosed with COVID-19 in the U.S. rose rapidly. Nearly one third (31%) of patients diagnosed, 45% of patients who were hospitalized, and over half (53%) of those admitted to intensive care units (ICU) were over the age of 65. This age group was also most likely to die. During this time period 80% of patients in the U.S. over the age of 65 did not survive (CDC COVID-19 Response Team, 2020, March 27).  These findings were consistent with the 80% mortality rate reported by Chinese scientists for patients over 60 (China CDC Novel Coronavirus Pneumonia Emergency Response Epidemiology Team, 2020, February 21).

COVID-19 Rages Uncontrolled

The virus crossed human designated borders with ease and local quarantines and shutdowns in many countries had minimal impact. The invisible pathogen passed from person to person without restraint. When the World Health Organization issued the 40th situation report on February 29, 2020, China had 79,394 confirmed cases with 2,838 deaths due to COVID-19. The case fatality rate in China had increased from 2.3 to 3.6% during that time. It is not known if the increase in case fatality was due to the ancestral strain or a variant as we were unable to find any information one way or another. Patients with COVID-19 infections had been confirmed in 53 countries for a global total of 85,403 (WHO 2020, February 29).

As shown in figure 4, there were several phases and interventions as the situation progressed from a local cluster of four patients linked to a single location ð to a local outbreak in Wuhan, a city in China, ð to a country wide epidemic, and then ð to a global pandemic with unbelievable speed.

To summarize:

  • 12/29/19 – 4 patients were hospitalized in Wuhan, China with an unknown respiratory disease.
  • 12/31/19 – China notified the World Health Organization that there was an outbreak of 47 patients with an unknown respiratory illness.
  • 1/3/20 – China had isolated the virus, identified it as a previously unknown Coronavirus, and completed genetic sequencing of the virus. The virus was named SARS-CoV-2 (severe acute respiratory syndrome, coronavirus 2), and the disease that the virus caused was named COVID-19.
  • 1/3/20 – China entered the first three ancestral viral genomes for the novel Coronavirus into the international database GISAID so that scientists worldwide could begin development of diagnostic tests that would identify the virus in clinical samples from patients and start working on a vaccine.
  • 1/11/20 – 248 patients had been identified and tested positive for SARS-CoV-2, all in China. Travel restrictions and stay-at-home orders in Wuhan, China were in place.
  • 11/21/20 – Cases in China were increasing, and the World Health Organization reported that patients with COVID-19 infections had been found in Thailand (2), the Republic of Korea (1), and Japan (1) – all of those who were ill had traveled to China.
  • 11/22/20 – Epidemiological studies showed that cases of COVID-19 were doubling every 7.2 days.
  • 11/22/20 – Asymptomatic transmission was identified, as 53% of the 378 patients with confirmed infections had not been exposed to a sick person. Fourteen-day quarantines were recommended.
  • 1/28/20 – The disease had spread to 15 countries and 106 deaths were recorded, there were 4,593 cumulative patients with confirmed disease and another 6,973 patients with suspected infection.
  • 1/29/20 – Chinese scientists published concerns about asymptomatic transmission in the New England Journal of Medicine.
  • 2/28/20 – Patients with infections were diagnosed in 53 countries and 705 patients had been become ill on the Diamond Princess, an international cruise ship based out of Japan. There were 85,403 patients who had been diagnosed worldwide. The case fatality rate had increased from 2.3% to 3.6%.
  • 3/16/20 – The transmission rate for COVID-19 was determined to be 2.75, each infected person passed on the infection to 2.75 other people.

The general public had many opportunities to learn about the modes of transmission, transmission-based precautions, and public health recommendations early in the pandemic. Sadly, many ignored even the simplest of methods to protect themselves and others.  

Despite all the pre-pandemic preparation that preceded arrival of this virus on earth, and worldwide efforts to contain COVID-19, the virus was able to overcome human interventions and continue burning through the population. Many factors contributed to this situation, and we will explore some of these in other sections. By March of 2020, the world’s people continued to fight a losing battle until effective vaccines became available.

As the number of cases of COVID-19 in the United States increased, so too did the amount of information that positively and negatively impacted spread of the virus. Accurate information regarding public health measures needed to prevent the spread of the infection were announced through mainstream television and radio reports. Physician and public health experts were brought in to explain the situation in lay terms. Public health officials announced prevention strategies via official websites, clinician letters, phone meetings, and information for the general public. Simple measures to prevent the spread of this highly contagious disease were suggested:

  • Hand hygiene with soap and water or alcohol based handrub.
  • Social distancing 6 feet apart.
  • Avoid crowds.
  • Disinfect surfaces and contaminated objects.      

Unfortunately, as the crisis worsened, there was a worldwide “infodemic” of misinformation, disinformation, and conspiracy theories put forth, especially on social media. This caused a great deal of confusion. Due to the amount of misinformation already spreading within the first days of the pandemic, the World Health Organization developed a “Mythbuster” website for fact checking (https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/myth-busters).

Disinformation and conspiracy theories had a major negative impact on worldwide efforts to mitigate the developing pandemic.

References Cited

Centers for Disease Control and Prevention Health Alert Network (2020 January 17). Update and interim guidance on outbreak of 2019 novel coronavirus (2019-nCoV) in Wuhan, China. https://emergency.cdc.gov/han/han00426.asp#print

Centers for Disease Control and Prevention (2021, May 7). Scientific Brief: SARS-CoV-2 transmission. https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/sars-cov-2-transmission.html#print

China Centers for Disease Control and Prevention, The 2019-nCoV Outbreak Joint Field Epidemiology Investigation Team (2020, January 31). An outbreak of NCIP (2019-nCoV) infection in China – Wuhan, Hubei Province, 2019-2020. China CDC Weekly, 2, 5, 79-80. https://weekly.chinacdc.cn/fileCCDCW/journal/article/ccdcw/2020/5/PDF/NCIP.pdf

China Centers for Disease Control and Prevention, Novel Coronavirus Pneumonia Emergency Response Epidemiology Team (2020, February 21). The epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19) – China, 2020. China CDC Weekly, 2, 8, 113-122. https://weekly.chinacdc.cn/fileCCDCW/journal/article/ccdcw/2020/8/PDF/COVID-19.pdf

Cohen, J., & Rodgers, Y. V. D. M. (2020). Contributing factors to personal protective equipment shortages during the COVID-19 pandemic. Preventive Medicine, 141, 106263.  https://doi.org/10.1016/j.ypmed.2020.106263

GISAID (2023a, January 20). About us. https://gisaid.org/about-us/mission/

GISAID (2023b, January 20). Official hCOV-19 reference sequence. https://gisaid.org/wiv04/

Leung, N. H. (2021). Transmissibility and transmission of respiratory viruses. Nature Reviews Microbiology, 19, 528-545. https://www.nature.com/articles/s41579-021-00535-6                                                                                                                              

Li, Q., et al. (2020, January 29 online). Early transmission dynamics in Wuhan, China, of novel coronavirus-infected pneumonia. The New England Journal of Medicine, 382, 13, 1199-1207. DOI: 10.1056/NEJMoa2001316. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7121484/pdf/NEJMoa2001316.pdf

Medley, A. M., et al. (2021). Use of U.S. public health travel restrictions during COVID-19 outbreak on Diamond Princess ship, Japan, February-April 2020. Emerging Infectious Diseases, 27, 3, 710-718. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7920645/pdf/20-3820.pdf

Siegel, J. D., Rhinehart, E., Jackson, M., Chiarello, the Healthcare Infection Control Practices Advisory Practices Committee. (2022, May). CDC 2007 guideline for isolation precautions preventing transmission of infectious agents in healthcare settings. Last update May 2022. https://www.cdc.gov/infectioncontrol/pdf/guidelines/isolation-guidelines-H.pdf

Stadnytskyi, V., et al. (2020). the airborne lifetime of small speech droplets and their potential importance in SARS-CoV-2. Proceedings of the National Academy of Sciences, 117, 22, 11875-11877. https://doi.org/10.5281/zenodo.3770559

Tan, W., et al. (2020, January 24). A novel coronavirus genome identified in a cluster of pneumonia cases – Wuhan, China 2019-2020.  China CDC Weekly, 2, 4, 61-62. https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2020.017

Wilson, M. E., & Chen, L. H. (2020). Travelers give wings to novel coronavirus (2019-nCoV). Journal of Travel Medicine, 1-3. doi: 10.1093/jtm/taaa015. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7107561/pdf/taaa015.pdf

World Health Organization (n.d.). Naming the coronavirus disease (COVID-19) and the virus that causes it. https://www.who.int/emergencies/diseases/novel-coronavirus-2019/technical-guidance/naming-the-coronavirus-disease-(covid-2019)-and-the-virus-that-causes-it#:~:text=Human%20disease%20preparedness%20and%20response,virus%20on%201120February%202020.

World Health Organization (2020, January 21). Novel Coronavirus (2019-nCoV) situation report – 1. https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200121-sitrep-1-2019-ncov.pdf?sfvrsn=20a99c10_4

World Health Organization (2020, January 28). Novel Coronavirus (2019-nCoV) situation report – 8, January 28, 2020. https://www.who.int/docs/default-sourcecoronavirussituation-reports/20200128-sitrep-8-ncov-cleared.pdf?sfvrsn=8b671ce5_2

World Health Organization (2020, January 31). Novel Coronavirus (2019-nCoV) situation report – 11. https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200131-sitrep-11-ncov.pdf?sfvrsn=de7c0f7_4

World Health Organization (2021, February). WHO-convened global study of origins of SARS-CoV-2 China part. Joint WHO-China study 14 January-10 February 2021 Joint Report. https://www.who.int/emergencies/diseases/novel-coronavirus-2019/origins-of-the-virus

World Health Organization (2020, February 29). Coronavirus disease 2019 (COVID-19) situation report 40. https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200229-sitrep-40-covid-19.pdf?sfvrsn=849d0665_2

Siegel, J. D., Rhinehart, E., Jackson, M., Chiarello, the Healthcare Infection Control Practices Advisory Practices Committee. (2022, May). CDC 2007 guideline for isolation precautions preventing transmission of infectious agents in healthcare settings. Last update May 2022. https://www.cdc.gov/infectioncontrol/pdf/guidelines/isolation-guidelines-H.pdf