Why Rapid Spread of a New Virus Is So Dangerous
Since the new coronavirus outbreak in January 2020, I have been trying to better understand why this virus and not the seasonal flu virus is receiving so much attention. We could track seasonal flu cases if desired, but we don’t. We don’t even routinely test for it, even though many people die of flu-related complications every year. The most recent estimate of global influenza-related death due to respiratory symptoms is between 290,000 and 650,000 people. That is a rather large number of influenza-related deaths and likely underestimates the total that have a contribution from influenza.
With SARS-CoV-2 (the name of the new coronavirus) and COVID-19 (the disease caused by SARS-CoV-2), countries are actively testing people and tracking infection data, recovery data, severity of disease data, and mortality data. We have a real-time tracking site by Johns Hopkins University, daily and multi-day news releases by WHO (World Health Organization), continuously updated information at CDC (Centers for Disease Control and Protection), researchers and publishers making their discoveries and related content freely available through an effort led by Wellcome Trust and that includes Springer Nature, New England Journal of Medicine, Science and its family of journals, and many others, and a new initiative by Bill & Melinda Gates Foundation, Wellcome, and Mastercard to help discover treatments for this and other emerging pathogens. And, of course, there has been overwhelming media coverage.
When a new virus enters the population, there is very little, if any, immunity against the virus in the population. If the virus causes severe symptoms and is spread fairly easily, as this SARS-CoV-2 does, then the medical systems can be quickly overwhelmed.
For seasonal flu, the spread of the influenza virus is limited partly by a level of immunity within the population and partly by annual vaccination. Additionally, the healthcare systems have a reasonable expectation of how the flu will impact the system and can be prepared. None of this possible with the COVID-19. Consequently, when the virus first appeared in Wuhan, China, it rapidly spread through the population and rapidly overwhelmed the existing medical care facilities. China took rapid action, built temporary hospitals, and employed massive testing and tracking of infected individuals and their contacts. They also enforced quarantines and took non-pharmaceutical measures to slow transmission.
Most countries cannot and would not take as extreme steps to contain the virus. However, there are steps that they can take. Unfortunately, many countries, including the US, have not put in place stringent social distancing and effectively tested and tracked infected individuals and their contacts. For Italy, the result has been a quarantine of the entire country and a massive overwhelming of the medical system in the worst affected areas.
When the Healthcare System Is Overwhelmed
What people may not realize is that, as medical systems become overwhelmed, even those who are not suffering from the new infectious disease can be affected. Most hospitals have a limited number of beds, ventilators, and other respiratory assistance devices. Even a hospital with only half of its beds occupied can easily become overwhelmed by an infection that follows a rapid spread through the community. When that happens, beds and effective care will not be available for anyone, not just those with a failing respiratory system due to the infection.
What doctors in Italy are reporting shows just how desperate the situation can become:
- Beds in hospitals become unavailable for treatment of other emergent patients (new heart patients, kidney patients, stroke patients, and so on)
- Ventilators and assisted respiratory systems go to infected patients and then become unavailable for new patients with respiratory failure due to infection or other causes
- Intensive care units fill with patients with respiratory failure
- Oxygen becomes limiting, and patients in need, whether because of infection or other conditions, do not have access
- Operations are cancelled or postponed so that those rooms can be used for COVID-19 patients
- Emergency departments are overwhelmed and begin to turn away patients who would normally receive care
- Patients older than 65 or younger with comorbidities are not assessed, because their chances of survival are too low given the high patient volume
- Doctors in many specialty areas are diverted to seeing patients suffering respiratory symptoms and on noninvasive ventilation
- Healthcare workers become exhausted and many eventually become infected, reducing the availability of healthcare providers and further compromising care
In the absence of effective treatments and vaccines, social distancing and good hygiene are the best strategies we can take to protect ourselves and prevent the rapid spike in virus transmission and COVID-19 cases. Social distancing is how we protect our most at-risk members of our families and communities. Even if you are not in a high-risk category, consider that you could become infected and spread the virus to others without becoming seriously sick yourself. You may not realize that a person near you is immune compromised or in a high-risk group or lives with someone who is.
Influenza: Burden of Disease. World Health Organization [accessed 10 March 2020] https://www.who.int/influenza/surveillance_monitoring/bod/en/
Estimate of Respiratory Deaths due to Seasonal Influenza. World Health Organization [English version] https://www.who.int/influenza/surveillance_monitoring/bod/WHO-INFLUENZA-MortalityEstimate.pdf?ua=1
A. D. Iuliano, et al., Estimates of global seasonal influenza-associated respiratory mortality: A modelling study. The Lancet 391, 1285–1300 (2018). DOI: 10.1016/S0140–6736(17)33293–2
Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19). https://www.who.int/docs/default-source/coronaviruse/who-china-joint-mission-on-covid-19-final-report.pdf [accessed 10 March 2020]
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