What We Know About COVID-19 So Far: A Summary of Information

By Kelly M. Pyrek

Editor’s note: As the World Health Organization (WHO) officially designates coronavirus disease 2019 (COVID-19) as a global pandemic, COVID-19 continues to be a rapidly moving target, and as new information is available, this article will be updated.

Essential Components of a Hospital Preparedness Plan for COVID-19

The Society of Critical Care Medicine estimates that approximately 95,000 critical care beds, including surgical and specialty unit beds, are available in U.S. hospitals today. COVID-19 has tested the preparedness of healthcare systems and challenged their readiness to care for a large influx of patients with this disease.

As Chopra, et al. (2020) acknowledge that, “Best-case estimates suggest that COVID-19 will stress bed capacity, equipment, and healthcare personnel in U.S. hospitals in ways not previously experienced.”

It is imperative that hospitals develop a strategy for patient volume and complexity. Chopra, et al. (2020) assert that healthcare systems may need twice the number of available beds to meet the demands triggered by the COVID-19 pandemic, should it become sustained. They add, “Because some patients will be critically ill and need scarce resources, such as extracorporeal membrane oxygenation and ventilators, hospitals must prepare now for how they will triage patients, allocate resources, and staff wards.”

Chopra, et al. (2020) emphasize the importance of geographically cohorting patients with COVID-19 to limit the number of healthcare personnel exposed and to conserve supplies: “This type of geographic capacity generation is extremely difficult because many U.S. hospitals run at full capacity. Geographic cohorting options may also be challenged by locations of airborne isolation rooms, with negative pressure being scattered throughout the hospital. It may be necessary to use innovative approaches, such as converting single rooms to double occupancy; expediting discharges; slowing admission rates; and converting spaces like catheterization laboratories, lobbies, postoperative care units, or waiting rooms into patient-care venues.”

For example, the researchers point out, at Michigan Medicine, “designated beds in critical care units and non–critical care settings for persons under investigation and patients who test positive for COVID-19 have been identified,” Chopra, et al. (2020) explain. “A dedicated team of hospitalists and critical care providers has been established, with clinical schedules and roles for leadership, communication, and activation criteria. Contingency plans have been developed, including activation criteria for opening a respiratory intensive care floor where cohorting of both critically ill and noncritically ill patients can occur. Similarly, ensuring the ongoing care of vulnerable patients, such as those in the posttransplant and immuno-compromised communities, remains imperative. Safe locations and staffing plans that separate vulnerable patients from COVID-19 activities have been carefully considered.”

Protecting healthcare personnel who are on the front lines of COVID-19 is essential. The evidence as it stands now indicates that the disease spreads primarily via droplet transmission and direct contact.

“With the appropriate precautions, nosocomial transmission can be mitigated,” say Chopra, et al. (2020). “Healthcare personnel should receive training on proper donning and doffing of personal protective equipment, including fit testing of N95 masks and use of powered air-purifying respirators, as well as basic infection prevention tenets, such as hand hygiene. Hospitals should monitor rates of equipment use to ensure an adequate supply of personal protective equipment for those on the front lines and may need to engage hospital security to avoid theft or hoarding of such equipment. Extended use or limited reuse of N95 respirators may become necessary, and communication about preservation is important.”

To limit the total number of personnel engaged in patient care, hospitals should institute overtime and extended hours with appropriate compensation strategies, the researchers advocate: “Clear exposure criteria with detailed plans outlining management of personnel in regard to work restrictions or other quarantine requirements must be developed,” say Chopra, et al. (2020). “Hospitals must also safeguard their own by keeping logs of staff who care for patients and monitoring them for signs or symptoms of infection. Finally, even if care of patients with COVID-19 will be provided by a subset of providers, it is important not to lose sight of the needs of their family members and other staff. Support is important to the morale and well-being of the workforce.”

Another imperative, according to the experts, is to allocate resources in an ethical, rational and structured way to benefit the greatest number of patients. As Chopra, et al. (2020) explain, “Hospitals and health systems must set aside a “business as usual” mentality and focus on how best to accommodate the patients likely to benefit the most from care. Specifically, a plan that outlines what services and types of procedures will be provided (for example, extracorporeal membrane oxygenation) and what will not (for example, elective cases) must be developed. Accordingly, clinical guidelines for use (or denial) of scarce services, such as mechanical ventilation and critical care, should be outlined, in consultation with ethics and medical staff. A protocol that defines how patients will be triaged for admission, observation, early discharge, and quarantine is important. Hospitals should anticipate that normal staffing ratios and some standards of care are unlikely to be maintained; plans for contingency and crisis standards that lay out a legal and ethical framework for care decisions, including who will make decisions, how, and under what circumstances, must be readied. At Michigan Medicine, scarce resource guidelines have not only been developed, but portions have been revised and circulated to staff to ensure agreement and buy-in for execution.”

Transmission Accelerates

Klompas (2020) says that it is “apparent that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is optimized to spread widely. It causes mild but prolonged disease, infected persons are contagious even when minimally symptomatic or asymptomatic, the incubation period can extend beyond 14 days, and some patients seem susceptible to reinfection. These factors make it inevitable that patients with respiratory viral syndromes that are mild or nonspecific will introduce the virus into hospitals, leading to clusters of nosocomial infections. The signs and symptoms of coronavirus disease 2019 (COVID-19) are largely indistinguishable from those of other respiratory virus infections. Less than one half of patients with confirmed disease have fever on initial presentation. The sensitivity of a single nasopharyngeal swab early in the course of disease is only 70 percent. Multiple reports already exist of delayed diagnoses leading to nosocomial transmissions.

How bad will it be? As Klompas (2020) emphasizes, “Characterizing the morbidity rate of COVID-19 is challenging because case detection in the early stages of an outbreak is biased toward severe disease. An initial series reported a mortality rate of 15 percent. A subsequent analysis that included patients who were less sick reported a mortality rate of 2.3 percent, but this is still likely an overestimate. Mortality rates are substantially lower outside than inside Hubei province, where the outbreak began (114 deaths among 13,152 patients [0.9%] vs. 2986 deaths among 67,707 patients [4.4%] as of March 8, 2020). This is presumably because of Hubei's initial focus on patients with severe disease, constraints on the province's testing and care capacity, and the passage of more time since the outbreak began in Hubei versus other provinces allowing more time for patients to declare themselves. More to the point, current mortality estimates minimally account for patients with mild or asymptomatic infections, an important aspect of this epidemic. Case detection is still primarily focused on identifying patients with fever, cough, or shortness of breath; this focus leads to underestimation of the number of infected persons, overestimation of the mortality rate, and ongoing spread of disease.”

Regarding what can be done to prevent further spread of infection, Klompas (2020) observes, “We have to be more aggressive about case detection. Current screening is still focused on identifying patients with foreign travel or contacts with known cases. Both of these foci no longer reflect the current status of this epidemic given increasing evidence of community spread. We need to be able to test patients with milder syndromes regardless of travel or contact history. The Centers for Disease Control and Prevention has updated its ‘person under investigation’ criteria to permit this, but there is still a severe shortage of readily available tests.”

Klompas (2020) adds, “More broadly, however, the best way to protect hospitals against COVID-19 is to bolster our approach to routine respiratory viruses (that is, influenza, respiratory syncytial virus, parainfluenza, adenovirus, human metapneumovirus, and “conventional” coronaviruses). This will simultaneously improve care for current patients, make work safer for clinicians, and help prevent the incursion of occult COVID-19 into hospitals. We underestimate the contagiousness and seriousness of routine respiratory viruses. We underappreciate that 30 percent to 50 percent of cases of community-acquired pneumonia are caused by viruses, that nosocomial transmission of respiratory viruses is common, and that “routine” respiratory viruses cause substantial morbidity and mortality that may not differ much from those caused by SARS-CoV-2 once minimally symptomatic COVID-19 is accounted for. Respiratory viruses infect millions of persons each year (about 10 percent of the population) and cause tens of thousands of deaths in the United States alone . They can cause severe pneumonia, predispose patients to bacterial superinfection, and exacerbate cardiac and pulmonary conditions up to and including death.”

Most hospitals, however, manage respiratory viruses passively, Klompas (2020) asserts, adding, “We rely on signs alone to deter visitors with upper respiratory tract infections from visiting, we isolate patients in private rooms only if they test positive for influenza virus (even though many other viruses can cause influenza-like syndromes that are equally morbid), we discontinue precautions in patients with acute respiratory tract syndromes if they test negative for viruses (even though viral tests have variable and imperfect sensitivity), we consider masks alone to be adequate protection (even though viruses can be transmitted via fomites and eye contact as well as mouth and nose contact), and we tolerate health care workers coming to work with upper respiratory tract infections so long as they are not febrile. Our halfhearted approach to endemic respiratory viruses is a source of harm to our patients and puts us at increased risk for COVID-19 infiltration. To cause a nosocomial outbreak, it will take just one patient with occult COVID-19 who is hospitalized, tests negative for influenza virus, and is taken off precautions despite persistent respiratory symptoms. Or just one visitor with COVID-19 and mild respiratory symptoms who is permitted free access to the hospital because it does not have an active screening and exclusion policy for visitors with respiratory tract symptoms. Or just one infected healthcare worker who decides to soldier through a shift despite a sore throat and runny nose.”

Experts are placing renewed emphasis on common-sense and evidence-based practices, including respiratory hygiene and placing restrictions on patients, visitors, and healthcare workers with even mild symptoms of upper respiratory tract infection.

Klompas (2020) adds, “Potential policies to consider include the following: 1) screening all visitors for any respiratory symptoms that may be related to a virus, including fever, myalgias, pharyngitis, rhinorrhea, and cough, and excluding them from visiting until they are better; 2) restricting healthcare workers from working if they have any upper respiratory tract symptoms, even in the absence of fever; and 3) screening all patients, testing for all respiratory viruses (including SARS-CoV-2) in those with positive screening results regardless of illness severity, and using precautions (single rooms, contact precautions, droplet precautions, and eye protection) for patients with respiratory syndromes for the duration of their symptoms regardless of viral test results. A collateral benefit is that if a patient is subsequently diagnosed with COVID-19, staff who used these precautions will be considered minimally exposed and will be able to continue working. None of these measures will be easy. Restricting visitors will be psychologically difficult for patients and loved ones, maintaining respiratory precautions for the duration of patients' symptoms will strain supplies in all hospitals and bed capacity in hospitals that depend on shared rooms, and preventing health care providers with mild illness from working will compromise staffing. But if we are frank about the morbidity and mortality of all respiratory viruses, including SARS-CoV-2, this is the best thing we can do for our patients and colleagues regardless of COVID-19.”

New Study on COVID-19 Estimates 5.1 Days for Incubation Period

An analysis of publicly available data on infections from the new coronavirus, SARS-CoV-2, that causes the respiratory illness COVID-19 yielded an estimate of 5.1 days for the median disease incubation period, according to a new study led by researchers at Johns Hopkins Bloomberg School of Public Health. This median time from exposure to onset of symptoms suggests that the 14-day quarantine period used by the Centers for Disease Control and Prevention (CDC) for individuals with likely exposure to the coronavirus is reasonable.

The analysis suggests that about 97.5 percent of people who develop symptoms of SARS-CoV-2 infection will do so within 11.5 days of exposure. The researchers estimated that for every 10,000 individuals quarantined for 14 days, only about 101 would develop symptoms after being released from quarantine.

The findings were published March 9, 2020 in the journal Annals of Internal Medicine.

For the study, the researchers analyzed 181 cases from China and other countries that were detected prior to February 24, were reported in the media, and included likely dates of exposure and symptom onset. Most of the cases involved travel to or from Wuhan, China, the city at the center of the epidemic, or exposure to individuals who had been to Hubei, the province for which Wuhan is the capital.

The CDC and many other public health authorities around the world have been using a 14-day quarantine or active-monitoring period for individuals who are known to be at high risk of infection due to contact with known cases or travel to a heavily affected area.

“Based on our analysis of publicly available data, the current recommendation of 14 days for active monitoring or quarantine is reasonable, although with that period some cases would be missed over the long-term,” says study senior author Justin Lessler, an associate professor in the Bloomberg School’s Department of Epidemiology.

The global outbreak of SARS-CoV-2 infection emerged in December 2019 in Wuhan, a city of 11 million in central China, and has resulted in more than 100,000 officially confirmed cases around the world and 3,282 deaths from pneumonia caused by the virus, according to the World Health Organization’s March 5 Situation Report. Most cases are from Wuhan and the surrounding Hubei province, although dozens of other countries have been affected, including the U.S., but chiefly South Korea, Iran, and Italy.

An accurate estimate of the disease incubation period for a new virus makes it easier for epidemiologists to gauge the likely dynamics of the outbreak and allows public health officials to design effective quarantine and other control measures. Quarantines typically slow and may ultimately stop the spread of infection, even if there are some outlier cases with incubation periods that exceed the quarantine period.

Lessler notes that sequestering people in a way that prevents them from working has costs, both personal and societal, which is perhaps most obvious when healthcare workers and first responders like firefighters are quarantined.

The new estimate of 5.1 days for the median incubation period of SARS-CoV-2 is similar to estimates from the earliest studies of this new virus, which were based on fewer cases. This incubation period for SARS-CoV-2 is in the same range as SARS-CoV, a different human-infecting coronavirus that caused a major outbreak centered in southern China and Hong Kong from 2002 to 2004. For MERS-CoV, a coronavirus that has caused hundreds of cases in the Middle East, with a relatively high fatality rate, the estimated mean incubation period is five to seven days.

Human coronaviruses that cause common colds have mean illness-incubation periods of about three days.

Lessler and colleagues have published an online tool that allows public health officials and members of the public to estimate how many cases would be caught and missed under different quarantine periods.

“The incubation period of COVID-19 from publicly reported confirmed cases: estimation and application” was written by co-first authors Stephen Lauer and Kyra Grantz, and Qifang Bi, Forrest Jones, Qulu Zheng, Hannah Meredith, Andrew Azman, Nicholas Reich, and Justin Lessler.

Keeping Frontline Healthcare Workers Safe

As we have seen, experts are emphasizing the need for healthcare personnel to keep precautions at the forefront as they care for the influx of COVID-19 patients.

Christopher Friese, professor of nursing at the University of Michigan School of Nursing and professor of health management and policy at the School of Public Health, leads a research team focused on healthcare delivery in high-risk settings. As the coronavirus spreads throughout the country, an increasing number of American healthcare workers helping to treat patients are contracting the infection.

Friese’s research has shown that healthcare workers often don’t receive the equipment and training they need, or they use the equipment improperly.

“To me, the strategy for any healthcare worker is first take care of yourself,” Friese says. “It’s the old analogy, when you’re on the airplane put your own mask on first. Take the time to study up on this problem. There are good resources at the CDC website to learn about this virus, how it spreads and what you can do to protect yourself. The second step is to practice these skills yourself. Don’t wait for your employer to roll out training, as this virus may be in your communities right now. We know from our work that despite training, nurses do not apply and remove their protective equipment as recommended, even during routine care. They’re subject to contamination. Healthcare workers need to practice this. They can’t assume they will do it right when the urgent matter arises.”

Friese continues, “Healthcare workers should have the conversation with their employer to make sure the supplies are present and the staff are trained on their correct use. One thing that happened with H1N1 about 10 years ago is that many hospitals supplied different masks than the staff were used to, and this led to failures because the staff didn’t know how to wear them properly. I think it’s important to stay connected to the CDC and WHO. We may learn over time that the guidance may change like it did with Ebola—the initial information was updated but it’s not clear all health care workers were updated with that new information. My strong recommendation is before each shift to take five minutes and check the CDC website to see if there have been changes. That may seem like a lot but we’re in uncertain territory, and personal, up-to-date knowledge is the best defense right now.”

Regarding healthcare workers and patients in home healthcare, nursing homes and outpatient clinics, Friese notes, “The problem in places like home health, nursing homes, and EMS is they’re under-resourced (in training and equipment). Workers in these settings are often part-time and work in multiple agencies or facilities, which allows the spread to happen more rapidly. Also, these environments are not designed to isolate patients; nursing homes often have two beds to a room, home health workers go house-to-house and EMS teams pick up dozens of patients a day—how do you clean and disinfect those spaces? All places that treat patients, particularly vulnerable patients, will need equipment and procedures to isolate patients and clean and disinfect surfaces.”

Friese emphasizes continued use of the practices and products that are proven to keep healthcare workers safe. “The most important thing is to wash your hands thoroughly with soap and water. Use a hand gel with 60 percent or higher alcohol concentration if soap and water aren’t available. For appropriate respiratory protection, the current recommendation from CDC is for healthcare workers to wear a gown, gloves, N-95 or higher-level respirator, and eye protection for patients with presumed or confirmed COVID-19. After removing the equipment carefully to avoid contamination, wash hands again. Unless you are told otherwise by the CDC, reusing personal protective equipment is not recommended.”

COVID-19 a Reminder of the Challenge of Emerging Infectious Diseases

The emergence and rapid increase in cases of COVID-19 poses complex challenges to the global public health, research and medical communities, write federal scientists from NIH's National Institute of Allergy and Infectious Diseases (NIAID) and from the Centers for Disease Control and Prevention (CDC). Their commentary appears in The New England Journal of Medicine.

NIAID director Anthony S. Fauci, MD, NIAID deputy director for clinical research and special projects; H. Clifford Lane, MD, and CDC director Robert R. Redfield, MD, shared their observations in the context of a recently published report on the early transmission dynamics of COVID-19. The report provided detailed clinical and epidemiological information about the first 425 cases to arise in Wuhan, Hubei Province, China.

In response to the outbreak, the United States and other countries instituted temporary travel restrictions, which may have slowed the spread of COVID-19 somewhat, the authors note. However, given the apparent efficiency of virus transmission, everyone should be prepared for COVID-19 to gain a foothold throughout the world, including in the United States, they add. If the disease begins to spread in U.S. communities, containment may no longer be a realistic goal and response efforts likely will need to transition to various mitigation strategies, which could include isolating ill people at home, closing schools and encouraging telework, the officials write.

Fauci, Lane and Redfield point to the many research efforts now underway to address COVID-19. These include numerous vaccine candidates proceeding toward early-stage clinical trials as well as clinical trials already underway to test candidate therapeutics, including an NIAID-sponsored trial of the experimental antiviral drug remdesivir that began enrolling participants on Feb. 21, 2020.

"The COVID-19 outbreak is a stark reminder of the ongoing challenge of emerging and re-emerging infectious pathogens and the need for constant surveillance, prompt diagnosis and robust research to understand the basic biology of new organisms and our susceptibilities to them, as well as to develop effective countermeasures," the authors conclude.

Persistence of Coronaviruses and Environmental Hygiene

One of the most unsettling aspects of coronaviruses is its persistence on inanimate surfaces. Kampf, et al. (2020) reviewed the literature on all available information about the persistence of human and veterinary coronaviruses on inanimate surfaces as well as inactivation strategies with biocidal agents used for chemical disinfection in healthcare facilities. The analysis of 22 studies reveals that human coronaviruses such as Severe Acute Respiratory Syndrome (SARS) coronavirus, Middle East Respiratory Syndrome (MERS) coronavirus or endemic human coronaviruses (HCoV) can persist on inanimate surfaces like metal, glass or plastic for up to none days, but can be efficiently inactivated by surface disinfection procedures with 62 percent to 71 percent ethanol, 0.5 percent hydrogen peroxide or 0.1 percent sodium hypochlorite within 1 minute. Other biocidal agents such as 0.05 percent to 0.2 percent benzalkonium chloride or 0.02 percent chlorhexidine digluconate are less effective.

Kampf, et al. (2020) report that ethanol (78–95%), 2-propanol (70–100%), the combination of 45% 2-propanol with 30% 1-propanol, glutardialdehyde (0.5–2.5%), formaldehyde (0.7–1%) and povidone iodine (0.23–7.5%) readily inactivated coronavirus infectivity by approximately 4 log10 or more. Sodium hypochlorite required a minimal concentration of at least 0.21% to be effective. Hydrogen peroxide was effective with a concentration of 0.5% and an incubation time of 1 minute. Data obtained with benzalkonium chloride at reasonable contact times were conflicting. Within 10 minutes, a concentration of 0.2% revealed no efficacy against coronavirus whereas a concentration of 0.05% was quite effective. 0.02% chlorhexidine digluconate was basically ineffective.

As Kampf, et al. (2020) explain, “Human coronaviruses can remain infectious on inanimate surfaces at room temperature for up to nine days. At a temperature of 30°C or more the duration of persistence is shorter. Contamination of frequent touch surfaces in healthcare settings are therefore a potential source of viral transmission. Data on the transmissibility of coronaviruses from contaminated surfaces to hands were not found. However, it could be shown with influenza A virus that a contact of 5 seconds can transfer 31.6 percent of the viral load to the hands. The transfer efficiency was lower (1.5 percent) with parainfluenza virus 3 and a 5 second contact between the surface and the hands.”

The researchers add, “Although the viral load of coronaviruses on inanimate surfaces is not known during an outbreak situation it seem plausible to reduce the viral load on surfaces by disinfection, especially of frequently touched surfaces in the immediate patient surrounding where the highest viral load can be expected. The WHO recommends ‘to ensure that environmental cleaning and disinfection procedures are followed consistently and correctly. Thoroughly cleaning environmental surfaces with water and detergent and applying commonly used hospital-level disinfectants (such as sodium hypochlorite) are effective and sufficient procedures.’ The typical use of bleach is at a dilution of 1:100 of 5% sodium hypochlorite resulting in a final concentration of 0.05 percent. Our summarized data with coronaviruses suggest that a concentration of 0.1 percent is effective in 1 minute. That is why it seems appropriate to recommend a dilution 1:50 of standard bleach in the coronavirus setting. For the disinfection of small surfaces ethanol (62 percent to71 percent; carrier tests) revealed a similar efficacy against coronavirus. A concentration of 70 percent ethanol is also recommended by the WHO for disinfecting small surfaces.”

No data were found to describe the frequency of hands becoming contaminated with coronavirus, or the viral load on hands either, after patient contact or after touching contaminated surfaces. As Kampf, et al. (2020) note, “The WHO recommends to preferably apply alcohol-based hand rubs for the decontamination of hands, e.g. after removing gloves. Two WHO recommended formulations (based on 80 percent ethanol or 75 percent 2-propanol) have been evaluated in suspension tests against SARS-CoV and MERS-CoV, and both were described to be very effective. No in vitro data were found on the efficacy of handwashing against coronavirus contaminations on hands. In Taiwan, however, it was described that installing hand wash stations in the emergency department was the only infection control measure which was significantly associated with the protection from healthcare workers from acquiring the SARS-CoV, indicating that hand hygiene can have a protective effect. Compliance with hand hygiene can be significantly higher in an outbreak situation but is likely to remain an obstacle especially among physicians. Transmission in healthcare settings can be successfully prevented when appropriate measures are consistently performed.”

Infection Control Measures

Appropriate hospital infection control measures could prevent nosocomial transmission of COVID-19, experts say. Cheng, et al. (2020) sought to describe the infection control preparedness for COVID-19) due to SARS-CoV-2 in the first 42 days after announcement of a cluster of pneumonia in China, on Dec. 31, 2019 (day 1) in Hong Kong.

The researchers implemented a bundle approach of active and enhanced laboratory surveillance, early airborne infection isolation, rapid molecular diagnostic testing, and contact tracing for healthcare workers (HCWs) with unprotected exposure in the hospitals. Epidemiological characteristics of confirmed cases, environmental and air samples were collected and analyzed.

Cheng, et al. (2020) report that from day 1 to day 42, 42 (3.3%) of 1,275 patients fulfilling active (n=29) and enhanced laboratory surveillance (n=13) confirmed to have SARS-CoV-2 infection. The number of locally acquired case significantly increased from 1 (7.7%) of 13 [day 22 to day 32] to 27 (93.1%) of 29 confirmed case [day 33 to day 42] (p<0.001). Twenty-eight patients (66.6%) came from 8 family clusters. Eleven (2.7%) of 413 HCWs caring these confirmed cases were found to have unprotected exposure requiring quarantine for 14 days. None of them was infected and nosocomial transmission of SARS-CoV-2 was not observed. Environmental surveillance performed in a patient with viral load of 3.3x106 copies/ml (pooled nasopharyngeal/ throat swab) and 5.9x106 copies/ml (saliva) respectively. SARS-CoV-2 revealed in 1 (7.7%) of 13 environmental samples, but not in 8 air samples collected at a distance of 10 cm from patient’s chin with or without wearing a surgical mask.

As the researchers observe, “The emergence of novel coronavirus associated pneumonia posed a global threat and challenges to the community as well as the healthcare system. In response to this unprecedented outbreak, which had already produced a higher number of infected case and mortality as compared with outbreak of SARS-CoV in 2003 within the first six weeks of its declaration, a rapid infection control response is essential to contain and mitigate the risk of nosocomial transmission and outbreak. With reference to experience in the outbreak of SARS-CoV, almost 60 percent of nosocomial acquisition of SARS-CoV was HCWs, it is critically important to implement proactive infection control measures, which must be planned ahead.”

The researchers say they enhanced the infection control measures at their institution by implementation of standard, contact, droplet, and airborne precautions for suspected or confirmed cases. “We stepped up the use of PPE among HCWs in performing aerosol generating procedures (AGPs), even when caring for patients without clinical features and epidemiological exposure risk in the general wards. Performance of AGPs such as endotracheal intubation, open suctioning, and use of high flow oxygen had been shown to be associated with the risk factors for nosocomial transmission of SARS-CoV among HCWs. In addition, provision of surgical masks to all HCWs, patients, and visitors in clinical areas was implemented since day 5. Although wearing surgical masks alone was not clearly associated with protection of person from acquisition of SARS-CoV, wearing surgical masks by either HCWs or patients had shown to reduce the risk of nosocomial transmission of influenza pandemic. The combination of hand hygiene with facemasks was found to have statistically significant efficacy against laboratory-confirmed influenza in the community as illustrated in a systematic review and meta-analysis. Hand hygiene among HCWs and patients was promoted and enforced during the epidemic of SARS-CoV-2. With all these measures, we could maintain zero nosocomial transmission of SARS-CoV-2 since the importation of first confirmed case since day 22 in Hong Kong.”

The researchers add, “With the implementation of active and enhanced surveillance with progressive widening of screening criteria during the evolution of epidemic, we could recognize most of the confirmed cases upon hospitalization and achieved zero nosocomial transmission in HCWs and patients within the first six weeks. However, our surveillance program may be challenged by patients with mild symptoms. In the early publications, fever and cough were reported in 87 percent and 80 percent of patients, respectively, at the time of presentation. With the presence of locally acquired cases, epidemiological criteria may no longer be useful for admission screening. Vigilance in hand hygiene practice, wearing of surgical masks in the hospital, and appropriate use of PPE in patient care, especially performing AGPs, are the key infection control measures to prevent nosocomial transmission of SARS-CoV-2 even before the availability of effective antiviral agents and a vaccine.”

To summarize, the researchers, from Queen Mary Hospital in Hong Kong, reported that zero healthcare workers contracted COVID-19 and no hospital-acquired infections were identified after the first six weeks of the outbreak, even as the health system tested 1,275 suspected cases and treated 42 active confirmed cases of COVID-19. Eleven healthcare workers, out of 413 involved in treating confirmed cases, had unprotected exposure and were quarantined for 14 days. None became ill.

“Appropriate hospital infection control measures can prevent healthcare-associated transmission of the coronavirus,” study authors say. “Vigilance in hand-hygiene practice, wearing of surgical masks in the hospital, and appropriate use of personal protective equipment in patient care, especially when performing aerosol-generating procedures, are the key infection control measures to prevent hospital transmission of the virus.”

Researchers also conducted an experiment taking air samples from close to the mouth of a patient with a moderate level of viral load of coronavirus. The virus was not detected in any of the tests, whether the patient was breathing normally, breathing heavily, speaking or coughing, and tests of the objects around the room detected the virus in just one location, on a window bench.

“The descriptive study employed unique environmental and air samples with the results suggesting that environmental transmission may play less of a role than person to person transmission in disease propagation,” says Gonzalo Bearman, MD, professor of medicine and chair of the Division of Infectious Disease at Virginia Commonwealth University, who reviewed but was not involved in the study.

When the first reports of a cluster of pneumonia cases came from Wuhan, Hong Kong’s 43 public hospitals stepped up infection control measures by widening screening criteria to include factors like visits to hospitals in mainland China. When the screening process identified a patient infected with the coronavirus, the patient was immediately isolated in an airborne infection isolation room or, in a few cases, in a ward with at least a meter of space between patients.

Enhanced infection control measures were put in place in each hospital, including training on the use of personal protective equipment, staff forums on infection control, face-to-face education sessions, and regular hand-hygiene compliance assessments. Hospitals also increased the use of personal protective equipment for healthcare workers performing aerosol generating procedures like endotracheal intubation or open suctioning for all patients, not just those with or at risk for COVID-19.

During the first six weeks of the outbreak, the number of locally acquired cases of COVID-19 in Hong Kong increased from 1 of 13 cases confirmed in the first 32 days of surveillance to 27 of 29 cases confirmed from day 33 to 42. Of the locally acquired cases, 28 came from eight family clusters with 11 cases likely transmitted during a gathering for “hot pot,” where utensils contaminated with saliva were comingled in shared pots. This family included a 91-year-old woman and a child who both tested positive for the virus but did not display symptoms.”



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