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In just three months, COVID-19 has spread from Wuhan, China, to at least 175 countries around the world, bringing with it a host of challenges for governments and societies as a whole. As of March 26, the United States topped the charts as the country with the highest number of reported positive cases in the world—and the numbers continue to grow.

Darin Seehafer
Darin Seehafer
Sr. Director, Center for Vaccines and Emerging Infectious Diseases

Let’s take a look at how we got here:

December 31, 2019
First cases reported to the World Health Organization (WHO)
Chinese authorities alert WHO of several cases of pneumonia with an unknown cause in Wuhan City, China.

January 7, 2020
Chinese authorities identify a new type of coronavirus
Researchers determine the cases are caused by a novel strain of coronavirus, SARS-CoV-2. Chinese scientists sequence the genome of SARS-CoV-2 and make the data available to researchers around the world. Using the sequencing data, researchers conclude the virus was a result of natural selection and not a product of genetic engineering.

January 11, 2020
China reports first death due to the novel coronavirus

January 13-30, 2020
First cases outside of China reported
Thailand reports the first case outside of China on January 13. On January 20, both the US and South Korea report their first cases. Two patients in the UK test positive on January 29, followed by Italy’s first two cases on January 30.

January 23, 2020
Wuhan placed under quarantine
A few days later, the entire Hubei province follows suit.

January 30, 2020
WHO declares a public health emergency

February 9, 2020
The death toll in China surpasses that of SARS epidemic

February 12-21, 2020
Cases start to spike outside of China
South Korea sees a spike in cases on February 12. On February 19, the outbreak in Iran begins. By February 21, Italy’s outbreak begins.

February 29, 2020
US reports first COVID-19 death

March 8, 2020
Italy places all residents on lockdown

March 11, 2020
WHO declares COVID-19 a pandemic

March 17, 2020
Italy reports the highest single-day death toll since the outbreak began
Italy reports 475 COVID-19 deaths in one day. By March 20, the highest single-day death toll reaches 627 in Italy, followed by 793 on March 21.

March 26, 2020
US surpasses China and Italy in confirmed cases
On March 26, the US officially overtakes China and Italy as the country with the most confirmed COVID-19 cases, while global cases exceed 531,000.

April 6, 2020
1,289,380 cases confirmed globally
As of publishing, 1,289,380 cases have been confirmed around the world, with the global death toll reaching 70,590.

Where did COVID-19 come from?

Coronaviruses themselves are not new. They’re part of a large family of viruses known to cause illnesses that range widely in severity. The first known severe illness caused by a coronavirus occurred in 2003 with the Severe Acute Respiratory Syndrome (SARS) epidemic in China. In 2012, another outbreak of severe disease emerged in Saudi Arabia with Middle East Respiratory Syndrome (MERS).

COVID-19, SARS-CoV-2, and coronavirus are all different terms for the same disease continuum. While the pandemic is often referred to as the new coronavirus, the WHO’s official name for the clinical disease is COVID-19. The virus (causative agent) itself is known as SARS-CoV-2.

After sequencing the SARS-CoV-2 genome, scientists found that the overall molecular structure of the new novel coronavirus differed substantially from other already known coronaviruses. They determined that the new virus likely resulted from one of two possible scenarios:

  • The virus evolved through natural selection in a non-human host then jumped to humans in its current pathogenic state. This is how previous coronavirus outbreaks have emerged.
  • The virus jumped from an animal host into humans in a non-pathogenic state. Once in the human population, it evolved to its current pathogenic state.

Unlike SARS and MERS, COVID-19’s specific structure “allows it to bind at least 10 times more tightly” to its common host cell receptor. This factor, combined with the virus’s ability to potentially attack several organs at once, allows the COVID-19 virus to attack and spread much more rapidly than other coronaviruses we’ve seen. Additionally, infectious disease researchers found that “more than 10% of patients are infected by somebody who has the virus but does not yet have symptoms.

COVID-19 can efficiently replicate in the upper respiratory tract before moving into the lower respiratory tract. Rather than an abrupt onset of symptoms, infected individuals may experience symptoms similar to a common cold. Because symptoms often appear mild at first, many individuals go about their usual activities, further spreading the virus to others. Some cases present as non-life-threatening pneumonia, while others appear as severe pneumonia with acute respiratory distress syndrome (ARDS). These more severe cases typically begin with mild symptoms lasting seven to eight days before progressing to rapid deterioration and ARDS.

So, how do we fight it?

The current coronavirus situation looks much different than it did back in January. In China and South Korea, outbreaks appear to be leveling off due in large part to aggressive testing and quarantine efforts. The same cannot be said for a growing number of countries. As more cases are confirmed each day, the death toll continues to rise, and healthcare systems are pushed to their limits.

On March 3, the WHO warned that a “severe and mounting disruption to the global supply of personal protective equipment (PPE) – caused by rising demand, panic buying, hoarding, and misuse – is putting lives at risk.” Surgical masks, N95 respirators, gloves, and gowns are all in short supply, which puts medical professionals at even higher risk when caring for patients with the coronavirus. This is a devastating problem as infection rates begin to double, and even the most advanced healthcare systems become overwhelmed by cases. In the Lombardy region of Italy, for example, about 10% of COVID-19 patients required intensive care. At the same time, more and more medical staff tested positive for the virus themselves and were placed in quarantine, further stretching the system’s resources to their breaking point.

To avoid this situation elsewhere, experts warn that countries must “flatten the curve.” Put simply, this means “preventing and delaying the spread of the virus so that large portions of the population aren’t sick at the same time.” Data shows that the mortality rate increases when hospitals are overcrowded. By suppressing the rate of new infections, countries can provide relief to help already strained healthcare systems and minimize the impact of the illness.

To flatten the curve, governments are enforcing a variety of strategies, including:

  • Quarantines: Keeping individuals or groups of people who may have been exposed to the virus but are not showing symptoms away from others to stop the spread of disease.
  • Self-isolation: Similar to quarantine, but for individuals who are already sick or showing symptoms of the disease.
  • Social distancing: Avoiding large gatherings and maintaining a safe distance from others. Experts recommend individuals keep at least six feet distance from others and avoid spaces where crowds are likely, including schools, churches, concert halls, and public transportation.

Social distancing and quarantines can help but alone are not enough. For every confirmed COVID-19 case, it is estimated that another five to ten infected people within the same community will go undetected. Asymptomatic individuals and those that experience only mild illness often will not—or simply cannot—get tested. As a result, these individuals can unknowingly spread the virus to others who may experience life-threatening complications. Widespread testing can help detect and isolate individuals that have contracted or come in contact with the virus, further slowing the spread of disease.

To survive, COVID-19 relies on humans to transmit it—the virus cannot move on its own and only survives on contaminated surfaces for a finite period of time. By significantly reducing or eliminating social interactions and administering comprehensive testing, countries can slow the rate of infection, reducing crowding in hospitals and minimizing the mortality rate. If no effective action is taken, confirmed cases are likely to grow exponentially in the coming weeks and days.

While these measures can be effective in minimizing exposure and transmission of infection, they can also have a profound economic, societal, and psychological impact. Many industries are already feeling the effects of these policies, including small businesses, restaurants, tourism, travel, and entertainment. As the situation progresses, more and more workers face reduced hours, layoffs, and financial insecurity. Other essential workers—medical professionals, grocery store employees, and delivery workers to name a few—are faced with the difficult decision of continuing to go into a potentially unsafe work environment, risking their health and the health of their loved ones at home, or staying home and forfeiting an income.

Pandemics disrupt daily life and can fuel anxiety and obsessive-compulsive disorders. Many individuals may experience worries of becoming infected, obsessions with contamination, and cleaning and washing compulsions. The current outbreak may also lead to mood problems and sleep issues in some individuals. For many, the lack of social interaction and structure from a daily routine can result in depression, boredom, and loneliness. Others may experience frustration or anger due to perceived loss of agency and personal freedom. For individuals who are sick or have been exposed to someone with COVID-19, stigmatization is a legitimate concern.

These are challenges we’re all facing, at least until a vaccine is widely distributed, which could take another 12 to 18 months. While social distancing policies can help minimize the effects of the virus, they cannot eliminate it completely, and continued strategies to reduce the spread of infection will be critical moving forward.

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