COVID-19: Facts, myths and hypotheses

COVID-19: Facts, myths and hypotheses
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Misinformation, confusion and conspiracies make it difficult to know how to confront the coronavirus that has caused illness in more than 100,000 people worldwide and spread to nearly half the states in the U.S. Distinguishing reality from myths and hypotheses provides guidance to decrease the risks to ourselves and others; ignorance, on the other hand, causes panic. 

This is how it started 

In early December an individual from rural China arrived in Wuhan, the largest city in Hubei province. The traveler had been infected with a coronavirus that normally infects bats, a virus we now call SARS-CoV-2 which causes COVID-19. The virus, which somehow jumped from the bat species to humans (perhaps through an unknown intermediate species), typically causes a relatively mild disease in humans. The hypothesis that the virus was created in a laboratory is a myth. 

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The virus mutated

In Wuhan, the virus mutated — as RNA viruses do — and became capable of transmission between humans. It has spread rapidly, originating from a group of closely related, more aggressive viruses called the “L” virus. While most young, healthy patients have mild symptoms, some have an aggressive course of the disease.

The L virus seems to target and kill the cells that line the tiny air sacs, or alveoli. (Alveoli allow the exchange of oxygen to take place in the deepest parts of the lung; when they are damaged, oxygen cannot reach the blood.)

Initially infected individuals show no symptoms

Patients with fever and a cough started going to Wuhan’s hospitals because they could not breathe; they were put on respirators in intensive care units (ICUs) but soon overwhelmed the ICU space.

On Jan. 23, the Chinese government quarantined the entire city, but it was too late — an estimated 5 million people had left the city to celebrate the Chinese New Year, while others left when it became known that the city would be locked down. Five million is way too many; the infection could no longer be contained.

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Following international air travel, we can track the virus’s subsequent spread. 

A higher viral load and capacity to infect others occurs about two days before infected individuals develop symptoms, so symptom-screening does not prevent them from boarding airplanes. (Screening is based on checking body temperature, which remains normal in the early stages of infection.) Not only can infected individuals spread the virus once they reach their destinations but they can infect fellow passengers. Thus far, air travelers appear to be the major spreaders of the virus internationally.

The lady from Shanghai

One of these travelers, a Chinese woman from Shanghai, flew into Germany on Jan. 22 and, while there, infected a 33-year-old German man. SARS-CoV-2 was now in Europe. 

From Germany or China, in a possibly independent event, SARS-CoV-2 also reached — probably via air travel — northern Italy, where the first case of COVID-19 was diagnosed on Feb. 22. The incidence of infection there has doubled every 2.5 days. 

Hospitals overwhelmed

As of March 11th, 1,028 patients infected with SARS-CoV-2 were in ICUs in northern Italy, saturating nearly all ICU beds. Assuming that the number continues to double every 2.5 days, patients will have to be transferred to other regions in Italy, increasing the risk of further spreading the disease. 

The capacity of ICUs is limited, in every country. Once capacity is reached, the number of acutely ill patients becomes a health catastrophe, because new patients cannot be properly treated; doctors may have to decide who gets into ICUs, thus increasing the chances of their survival, and who doesn’t — a difficult decision. 

Elective surgeries cannot be performed

An additional problem is that serious elective surgeries — cardiac, brain or many cancer surgeries, etc. — can only be performed if ICU space is available. Thus, once ICU beds are at saturation, all elective surgeries must stop; that causes additional deaths, indirectly caused by the viral epidemic, in patients with other diseases who cannot be properly treated. This happened in Wuhan a few weeks ago and may happen in Italy now. Elective surgeries are how hospitals make money; if hospitals cancel elective surgeries for a protracted time, governments will have to step in with extra money to protect them from bankruptcy.

Putting people in quarantine

These are the reasons we put people in quarantine. Not to stop the epidemic, because it cannot be stopped; too many are infected around the world, and people keep traveling, further spreading the disease. Instead, the goal of quarantine is largely to reduce the speed at which the epidemic spreads, in order not to saturate ICU beds.

Let us look at some numbers

About 80 percent of infected people have mild flu-like disease and require no treatment; 20 percent develop severe symptoms and, of those, about 5 percent are sick enough to be placed in ICUs. So far in Italy, 30 percent of patients placed in ICUs have died, contrasted to 50 percent in Wuhan. No specific therapy has proven to be more effective, but clinical trials are ongoing and there is hope that U.S. pharmaceutical companies will develop more effective drugs before year’s end. As for a vaccine, it will take more than one year to be ready for production and mass vaccination. 

People at greater risk

This infection is much more aggressive for certain groups. Few people under age 30 have died, compared to less than 1 percent of those younger than 50, about 4 to 5 percent of those between 50 and 70, and about 20 percent of those older than 70. Cancer patients — probably because of immunosuppressive therapies — and patients with cardiac disease, hypertension, or diabetes are at higher risk of dying. 

Testing

Testing has been uneven. The published rate of infection in different countries is largely influenced by the number of tests performed. For example, in northern Italy and South Korea, thousands have been tested and many found positive. In contrast, until last week, nobody had been tested in most U.S. states or in other countries. This is similar to what would happen if we removed all thermometers and then declared that no one has a fever. 

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Limited testing only postpones recognition of the problem and, when we are forced to confront it because ICUs are at capacity, the problem is difficult to deal with, which is what happened in Italy that is now experiencing a crisis. Only by extensive testing and implementing quarantine measures for those who test positive, like they are doing in South Korea — similar to those implemented in China, after officials there acknowledged an epidemic was occurring (and which is now experiencing a decline in cases) — can we contain and delay the speed of the epidemic so that it becomes manageable. 

Precautions we can take

Routine medical meetings planned in the coming months in the U.S. and abroad are now canceled; while doctors may appreciate the risks more acutely than most people, others may want to follow their example. We should avoid attending conferences or public gatherings where we are in close contact in enclosed spaces — six people were infected attending a funeral, for example.

Importantly, we should avoid traveling unless absolutely necessary. Many U.S. companies are allowing employees to work from home, which will help contain the epidemic; precautions similar to those to prevent flu, such as washing hands frequently, also reduces the risk of coronavirus infection. And, hopefully, by summer, the epidemic may wind down and the disease may be more manageable as effective drugs are identified.

Michele Carbone, M.D., Ph.D., is a pathologist, cancer researcher and molecular geneticist and performed a three-year fellowship in the Viral Pathogenesis Section at the National Institutes of Health (NIH). He is the William & Ellen Melohn Chair in Cancer Biology and director of thoracic oncology at the University of Hawaii Cancer Center, and a professor of pathology at the John A. Burns School of Medicine, Honolulu.

Enrico Bucci, Ph.D., is an adjunct professor at the Sbarro Institute for Cancer Research and Molecular Medicine, Temple University, Philadelphia.