It is becoming increasingly clear that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is optimized to spread widely . It causes mild but prolonged illness, infected people are contagious even when minimally symptomatic or asymptomatic, the incubation period can extend beyond 14 days, and some patients appear 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, giving rise 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 half of patients with confirmed disease have fever at initial presentation. The sensitivity of a single nasopharyngeal swab early in the course of the disease is only 70%. There are already multiple reports of delayed diagnoses leading to nosocomial transmissions.
How bad will it be?
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% .
A later analysis that included patients who were less sick reported a mortality rate of 2.3% , but this is still likely an overestimate. Mortality rates are substantially lower outside than within Hubei province, where the outbreak began (114 deaths among 13,152 patients [0.9%] vs. 2,986 deaths among 67,707 patients [4.4%] as of March 8 2020).
This is presumably due to Hubei’s initial focus on severely ill patients, limitations in the province’s testing and care capacity, and the passage of more time since the outbreak began in Hubei compared to other provinces, allowing more time for patients to declare themselves. Furthermore, current mortality estimates minimally represent patients with mild or asymptomatic infections, an important aspect of this epidemic.
| Case detection still primarily focuses on identifying patients with fever, cough, or shortness of breath; This approach leads to underestimation of the number of infected people, overestimation of the mortality rate, and continued spread of the disease. |
What can we do to prevent further spread of infection?
We have to be more aggressive with case detection.
Current evaluation still focuses on identifying patients with foreign travel or contacts with known cases. Both outbreaks no longer reflect the current state of this epidemic given the growing evidence of community spread. We need to be able to evaluate patients with milder syndromes, regardless of travel or contact history. The US Centers for Disease Control and Prevention has updated its "person under investigation" criteria to allow for this, but there is still a serious shortage of testing available.
More generally, however, the best way to protect hospitals against COVID-19 is to strengthen our approach to routine respiratory viruses (i.e., influenza, respiratory syncytial virus, parainfluenza, adenovirus, human metapneumovirus, and "conventional" coronaviruses). "). This will simultaneously improve care for current patients, make work safer for doctors, and help prevent the incursion of hidden COVID-19 into hospitals.
We underestimate the contagion and seriousness of routine respiratory viruses. We underestimate that 30% to 50% of community-acquired pneumonia cases are caused by viruses, that nosocomial transmission of respiratory viruses is common, and that "routine" respiratory viruses cause substantial morbidity and mortality that They may not differ much from those caused by SARS-CoV-2, once minimally symptomatic COVID-19 is accounted for.
Respiratory viruses infect millions of people each year (about 10% 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 heart and lung conditions leading to death.
However, most hospitals manage respiratory viruses passively . We rely on signs alone to discourage visitors with upper respiratory tract infections from visiting, we isolate patients in private rooms only if they test positive for the influenza virus (although 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 (although viral tests have variable and imperfect sensitivity), we consider masks alone to be adequate protection (although viruses can be transmitted to through fomites and eye contact, as well as mouth and nose contact), and we tolerate healthcare workers coming to work with upper respiratory tract infections as long as they are not febrile.
Our half-hearted approach to endemic respiratory viruses is a source of harm to our patients and puts us at greater risk of COVID-19 infiltration.
To cause a nosocomial outbreak , it will only take 1 patient with occult COVID-19 who is hospitalized, tests negative for the influenza virus, and precautions are taken despite persistent respiratory symptoms. Or only 1 visitor with COVID-19 and mild respiratory symptoms who has free access to the hospital because they do not have an active screening and exclusion policy for visitors with respiratory tract symptoms. Or just 1 infected healthcare worker who decides to soldier through a shift despite a sore throat and runny nose.
We need to be more aggressive about respiratory hygiene and put restrictions on patients, visitors and healthcare workers with mild symptoms of upper respiratory tract infection. Possible policies to consider include:
1) Screen all visitors for any respiratory symptoms that may be related to a virus, such as fever, myalgia, pharyngitis, rhinorrhea, and cough, and exclude them from the visit until they are better.
2) Restrict healthcare workers from work if they have any upper respiratory tract symptoms, even in the absence of fever.
3) Screening of all patients, testing for all respiratory viruses (including SARS-CoV-2) in those with positive screening results regardless of disease severity, and use of precautions (individual 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 later 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 deplete supplies at all hospitals and bed capacity at hospitals that rely on shared rooms, and will prevent Health care providers with mild illnesses may 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.
