The coronavirus from China refers to SARS-CoV-2, the virus first identified in Wuhan, China, in late 2019 that caused the global COVID-19 pandemic. On December 31, 2019, the Wuhan Municipal Health Commission reported a cluster of unusual pneumonia cases, and scientists soon identified the cause as a novel coronavirus, a type of virus named for the crown-like spikes on its surface.
How the Virus Was First Identified
In late December 2019, doctors in Wuhan, a city of about 11 million people in central China’s Hubei Province, noticed a pattern of severe pneumonia cases that didn’t match any known respiratory illness. Many of the early cases were linked to the Huanan Seafood Wholesale Market, which also sold live animals. Chinese health authorities alerted the World Health Organization on December 31, and within weeks, scientists had sequenced the virus’s genetic code and confirmed it belonged to the same family as SARS (Severe Acute Respiratory Syndrome), which caused a smaller outbreak in 2002-2003.
The virus was officially named SARS-CoV-2, and the disease it causes was named COVID-19 (short for “coronavirus disease 2019”). By January 2020, cases had appeared in Thailand, Japan, and South Korea. The WHO declared a global pandemic on March 11, 2020.
How SARS-CoV-2 Infects the Body
The virus spreads primarily through respiratory droplets and aerosols released when an infected person breathes, talks, coughs, or sneezes. Once inhaled, the virus uses a protein on its surface (the “spike” protein) to latch onto a specific receptor found on many human cells, particularly in the lungs, nose, and throat. This receptor, called ACE2, normally plays a role in regulating blood pressure. The virus essentially hijacks this receptor as a doorway into the cell, where it then copies itself and spreads to neighboring cells.
This attachment process is what made SARS-CoV-2 so effective at spreading between people. The spike protein binds to ACE2 receptors with high efficiency, and a second enzyme on human cell surfaces helps the virus complete its entry. Because ACE2 receptors exist throughout the body, including in the heart, kidneys, and intestines, COVID-19 can affect far more than just the lungs.
Symptoms and Severity
COVID-19 symptoms typically appear two to fourteen days after exposure. The most common include fever, cough, fatigue, shortness of breath, loss of taste or smell, sore throat, and body aches. For most people, especially those who are vaccinated, the illness is mild to moderate and resolves within one to two weeks.
Severe cases can lead to pneumonia, difficulty breathing, organ damage, and in some cases death. Older adults and people with underlying conditions like heart disease, diabetes, or weakened immune systems face higher risks of serious illness. Early in the pandemic, before vaccines were available, mortality rates were significantly higher.
Long COVID in China
A substantial number of people who recover from the initial infection go on to experience lingering symptoms for months or even years. A large-scale survey of more than 74,000 Chinese participants, one of the largest studies of its kind from China, found that roughly 10% to 30% of people reported Long COVID symptoms. The most common complaints were fatigue, memory decline, reduced exercise ability, and brain fog. These symptoms can persist regardless of how severe the original infection was.
China’s Vaccination Campaign
China mounted one of the world’s largest vaccination efforts, relying primarily on inactivated virus vaccines developed domestically. By March 2023, over 3.49 billion doses had been administered across the country, with approximately 92.8% of the population having received at least one dose.
The effectiveness of these vaccines varied depending on the variant. Against the Delta variant, full vaccination provided an estimated 52% to 68% effectiveness at preventing infection, depending on how the data was adjusted. Against the Omicron subvariants BA.1 and BA.2, which became dominant in 2022, the vaccines showed no significant difference in effectiveness between the two sublineages, though overall protection against infection was lower than against earlier variants. The vaccines were more effective at preventing severe illness and death than at blocking infection entirely.
How the Virus Has Evolved
Like all viruses, SARS-CoV-2 has mutated repeatedly since 2019, producing a series of variants. The major ones included Alpha, Delta, and Omicron, each more transmissible than the last. Omicron and its many subvariants became dominant worldwide starting in late 2021 and continued to evolve into dozens of sublineages. More recently, newer subvariants like BA.3.2 have been detected across multiple countries, including in Hong Kong. The virus continues to circulate globally, though the severity of illness has generally decreased as population-level immunity from both vaccination and prior infection has grown.
China’s Healthcare Response
China initially pursued a strict “zero-COVID” policy, using lockdowns, mass testing, and quarantine measures to suppress transmission. This approach kept case numbers low for nearly three years but came with significant economic and social costs. In December 2022, China abruptly lifted most restrictions, leading to a massive wave of infections across the country.
The pandemic exposed gaps in China’s critical care infrastructure. In response, the government set a goal of reaching 15 intensive care beds per 100,000 people by the end of 2025, including both dedicated ICU beds and an additional 10 beds per 100,000 that could be converted for intensive care use during surges. This expansion represented a significant increase from pre-pandemic capacity and reflected lessons learned about the strain that large outbreaks place on hospital systems.