A virus is a small infectious organism—much smaller than a fungus or bacterium—that must invade a living cell to reproduce (replicate). The virus attaches to a cell (called the host cell), enters the cell, and releases its DNA or RNA inside the cell. The virus’s DNA or RNA is the genetic material containing the information needed to make copies of (replicate) the virus. The virus’s genetic material takes control of the cell and forces it to replicate the virus. The infected cell usually dies because the virus keeps it from performing its normal functions. When it dies, the cell releases new viruses, which go on to infect other cells. Viruses are classified as DNA viruses or RNA viruses, depending on whether they use DNA or RNA to replicate.
Coronaviruses are a family of RNA viruses that infect and cause disease in mammals and birds. In humans they typically cause upper respiratory infections that can range from mild to fatal.
Coronaviruses constitute the subfamily Orthocoronavirinae, in the family Coronaviridae. They have characteristic club-shaped spikes that project from their surface, which in electron micrographs create an image reminiscent of the stellar corona, from which their name derives.
Alphacoronaviruses and betacoronaviruses infect mammals, while gammacoronaviruses and deltacoronaviruses primarily infect birds.
Betacoronaviruses (β-CoVs or Beta-CoVs) are one of four distinct genera of coronavirus. Member viruses are enveloped, positive-strand RNA viruses that infect mammals (including humans). The natural reservoir for betacoronaviruses are bats and rodents. Rodents are the reservoir for the subgenus Embecovirus, while bats are the reservoir for the other subgenera.
Each coronavirus genera are composed of various viral lineages with the betacoronavirus genus containing four such lineages: A, B, C, and D.
Severe acute respiratory syndrome-related coronaviruses (SARS-CoV) are a species of coronavirus (family Coronaviridae) within the genus Betacoronavirus and the subgenus Sarbecovirus (ie. SARS Betacoronavirus). Bats serve as the main host reservoir species for the SARS-related coronaviruses. While SARS-coronaviruses have evolved in bats for thousands of years, they have only recently evolved to be able to jump into other species, including humans.
There have been two strains of SARS-CoV that have infected humans, and both have caused significant outbreaks.
Severe acute respiratory syndrome coronavirus 1 is a SARS-related coronavirus that is responsible for causing the disease SARS (Severe Acute Respiratory Syndrome). It is the virus responsible for the SARS outbreak in 2002-2004 which affected thousands across the globe and resulted in over 750 deaths worldwide.
Severe acute respiratory syndrome coronavirus 2 is a SARS-related coronavirus that causes the disease COVID-19 (coronavirus disease 2019), which was first discovered in Wuhan, China in late 2019 and within weeks of its identification spread across the globe, causing the worst pandemic in modern history.
In early 2020, in the span of a few short weeks, nearly every person on earth found their lives upended by a novel coronavirus discovered in December 2019 in Wuhan, China.
On December 31, 2019 China alerted officials at the World Health Organization of a cluster of cases in Wuhan of pneumonia with unknown cause. A week later, on January 7, 2020 Chinese officials identify the cause, a novel coronavirus, two days after researchers submit the genetic sequence for this atypical pneumonia virus, Wuhan-Hu-1.
On January 10th the World Health Organization begins referring to this new virus as the “2019 Novel Coronavirus” or “2019-nCoV”. The virus later became known as SARS-CoV-2 and the disease it caused was called COVID-19 (coronavirus disease 2019).
Almost exactly one month after the World Health Organization was notified of the new virus, on January 30, 2020 WHO’s International Health Regulation Emergency Committee declared the 2019 Novel Coronavirus outbreak a Public Health Emergency of International Concern (PHEIC). This was the 6th time WHO had declared a PHEIC since the International Health Regulations (IHR) came into force in 2005. The WHO's situation report from that day reported a total of 7,818 confirmed cases worldwide and 170 deaths, including 82 confirmed cases in 18 countries outside of China.
It was nearly 6 weeks later, on March 11, 2020, when the WHO would characterize the outbreak a "pandemic". By then there were 118,319 confirmed cases worldwide and 4,292 deaths (of which there were 37,364 cases and 1,130 deaths from 113 countries and territories outside of China).
On January 23, 2020, Wuhan, China -- a city of 11 million people -- and other cities in the province of Hubei are placed under lockdown due to the spread of the 2019 novel coronavirus outbreak. All public forms of transportation (trains, buses, airports, ferries, and major highways) were shut down. The residents of Wuhan were also not allowed to leave the city without permission from the authorities. However, the directive was announced at 2am that the lockdown would begin at 10am, leading to a mass exodus of people from Wuhan, likely further spreading the virus. By the end of the day on January 24th, 12 other cities in Hubei were placed under lockdown, affecting 50 million people. The lockdown in Wuhan was finally lifted on April 8th, with transportation resuming, but residents still needed clearance to come and go from the city.
Italy became the first country outside of China to impose a lockdown due to COVID-19. Decree-Law No. 6 was passed by the Italian government on February 23, 2020, with contained urgent measures to contain and manage the epidemiological emergency, effectively locking down the country.
In the United States, Washington became the first state to declare a public health emergency on February 29, 2020 - by March 13th all 50 states had followed suit. California was the first state to enact stay-at-home orders on March 19th (though Puerto Rico actually enacted one first on March 15th).
In New York, Governor Cuomo issued a state of emergency on March 7th, restricted large gatherings and shut down SUNY/CUNY schools on March 12th, and finally on March 15th he ordered all New York City public schools (the largest school system in the country with 1.1 million students) to immediately close. On March 20, 2020 New York State declared state-wide stay-at-home orders. All non-essential businesses were ordered to close. All non-essential gatherings were canceled/postponed.
While most of the rest of the world had significantly less restrictive lockdowns than those in enacted in China, by April 2020 almost half of the world's population was under some form of lockdown measures, with more than 3.9 billion people in more than 90 countries or territories having been asked or ordered to stay at home by their governments.
The COVID-19 pandemic impacted nearly every facet of our lives and of society as a whole, from the personal impacts on individuals and their families, to the morbidity and mortality caused by the infection, broad psychological and mental health challenges, to socioeconomic and racial/ethnic structures, disparities, education, employment, and access to healthcare, to the global economies and supply chains, international relations, scientific communication, medical research, and technological advancements, and even the environment.
While there have been many epidemics and pandemics throughout history, there has never been one that so rapidly and completely altered the dynamics of life on this planet as COVID-19.
On February 9, 2023 the U.S. Department of Health and Human Services (HHS) announced that the U.S. Public Health Emergency (PHE) for COVID-19, declared under Section 319 of the Public Health Service (PHS) Act, would expire at the end of the day on May 11, 2023. The emergency declaration gave the government flexibility to take actions and access emergency funding to respond to the COVID-19 outbreak.
The separate U.S. National Emergency Concerning the Coronavirus Disease 2019 (COVID-19) Pandemic, declared by then President Trump and renewed by President Biden, was set to expire the same day, however on April 11, 2023, a month earlier than anticipated after pressure from Congressional Republicans, President Biden signed a bipartisan congressional resolution to bring it to a close after three years. The national emergency allowed the government to take sweeping steps to respond to the virus and support the country's economic, health and welfare systems. Some of the emergency measures have already been successfully wound-down, while others are still being phased out.
On May 4, 2023, the World Health Organization's International Health Regulations Committee (IRC) met and advised that it is time to transition to long-term management of the COVID-19 pandemic. The WHO Director-General, Dr. Tedros Ghebreyesus, agreed with the committee's recommendations. He determined that COVID-19 is now an established and ongoing health issue which no longer constitutes a public health emergency of international concern (PHEIC).
The IRC acknowledged that although SARS-CoV-2 has and will continue to circulate widely and evolve, it is no longer an unusual or unexpected event. The Director-General may decide to convene an IHR Emergency Committee on COVID-19 in the future if the situation requires.
The impacts of COVID-19 go far beyond the 2020, and impact society in ways that we likely don't even yet know or understand. The impacts of "Long COVID", and the potential of a mass disabling of society in the years that follow, it something that scientists are just now beginning to uncover. On May 3, 2023 the World Health Organization published their 2023-2025 COVID-19 Strategic Preparedness and Response Plan, From emergency response to long-term COVID-19 management: sustaining gains made during the COVID-19 pandemic, with a focus on supporting countries as they are transitioning from critical emergency response activities to longer-term sustained COVID-19 disease prevention, control and management.
