Epidemiology is the study of how diseases affect the health and illness of groups of people.
On 31 December 2019, Chinese health authorities reported to the World Health Organization (WHO) a cluster of viral pneumonia cases of unknown cause in Wuhan, and an investigation was launched in early January 2020.
On 9 June 2020, a Harvard University study suggested that COVID-19 may have been spreading in China as early as August 2019, based on hospital car park usage and web search trends.
Cases means the number of people who have been tested for COVID-19 and have tested positive. These cases are according to University.
Most people who contract COVID-19 recover. For those who do not, the time between the start of symptoms and death usually ranges from 6 to 41 days, but most of the time about 14 days. This data are recorded by the WHO.
On 11 March 2020, the WHO said that the pandemic could be controlled.
According to the United States Centers for Disease Control and Prevention, COVID-19 makes people feel sick in different ways, but it usually affects the lungs. People usually cough and have difficulty breathing. They often also have a fever, chills, headache, pain in their muscles, or trouble tasting or smelling things, which can often be confused with the flu virus.
According to an April 2020 study by the American Gastroenterological Association, COVID-19 can make sick people vomit or have diarrhea, but this is rare. They said about 7.7% of COVID-19 patients vomited, about 7.8% had diarrhea and about 3.6% had pain in their stomachs.
In February 2020, the WHO announced a name for the disease caused by SARS-CoV-2: COVID-19. It replaced the name "2019-nCoV." "Covi" is for "coronavirus," "D" for "disease," and "19" for the year 2019-- the year it was first detected. They said they did not want the name to have any person, place, or animal in it because people might blame the disease on that place, person, or animal. For example, it did not use the word "Wuhan." They also wanted the name to be easy to say out loud.
According to an article in Market Watch dated on February 27, 2020, the overall case mortality rate in China was 2.3%. However, these results might be severely different between different age groups and between men and women. People over the age of 70 experienced a rate of mortality 4-5 times that of the average. Men were more likely to die than women (2.8% versus 1.7% for women) possibly due to lifestyle, such as it being more possible in men to drink and smoke, making the risk of having a respiratory illness more possible, and thus more vulnerable. These numbers were the conclusion of a study by the Chinese Center for Disease Control and Prevention using 72,314 COVID-19 cases in mainland China as of Feb. 11. At that point this was the largest sample of cases for such a study.
On March 5, 2020, the WHO released the case fatality rate.
COVID-19 did not affect everyone in each country the same way. As of May 2020, APM Research Lab said the death rate among black Americans was 2.4 times as high as for whites and 2.2 times as high as for Latino and Asian Americans. In July 2020, The New York Times printed data from the Centers for Disease Control showing that black and Latino Americans were three times as likely to become sick and twice as likely to die as white Americans. This was not only in large cities but also in rural areas. This was not only for old people but for people in all age groups. Native Americans were also more likely than whites to become sick and die. Asian Americans were 1.3 times as likely as whites to become sick.
Camara Jones, an epidemiologist who once worked for the Centers for Disease Control and Prevention said this was socioeconomic and not because of any natural difference in black and white people's bodies. In the United States, black citizens are more likely to work jobs where they serve the public directly and to ride on public transport rather than take their own cars to work. This makes them more likely to be infected than people who work in private offices or from home. Sharrelle Barber, an epidemiologist and biostatistician from Drexel University, also said black Americans can live in crowded neighborhoods where social distancing is harder to do and healthy food harder to find. Both Barber and Jones blamed the long history of racism in the United States for these things. Three senators, Kamala Harris, Cory Booker and Elizabeth Warren said the federal government should start recording the race of COVID-19 patients so scientists could study this problem.
In June, the Centers for Medicare and Medicaid Services (CMS) told the public that people using the United States' government's Medicare health program had different results depending on race. Four times as many black Medicare patients went to hospitals for COVID-19 than white Medicare patients. There were twice as many hospitalized Hispanic patients than white patients. There were three hospitalized Asian patients for every two hospitalized white patients. The head of CMS, Seema Verma, said this was mostly because of socioeconomic status.
In the United Kingdom, twice as many black COVID-19 patients died as white COVID-19 patients. Other non-white people, like people from India and Bangladesh, were also more likely to die of COVID-19 than whites. Britain's Office of National Statistics said that the differences in money and education explained some of this difference but not all of it. They also said they did not know whether non-white patients caught COVID-19 more often or whether they caught more severe cases. Only female Chinese Britons were less likely to die of COVID-19 than white Britons.
Native Americans in the United States have shown more deaths from COVID-19 than the rest of the U.S. As of May, the Navajo Nation had 88 deaths and 2,757 cases, and the money they had been promised by the government arrived several weeks late. Only 30% of the people in the Navajo Nation have pipes with running water, which made it difficult for people to wash their hands.
Scientists from Chapman University made a plan to protect the Tsimane people in Bolivia from COVID-19 and said this plan would also work for other indigenous peoples living on their own land. The scientists said that many indigenous peoples have problems that make COVID-19 more dangerous for them, like poverty, less clean water, and other lung diseases. Hospitals may be a long distance away, and racism can affect the way doctors and nurses react. But they also sometimes have things that help, like traditions of making decisions together and the ability to grow food nearby. The scientists found people who spoke the Tsimane language as a first language and made teams to go to Tsimane towns to warn them about COVID-19. They also used radio stations. They said the best plan was for whole communities to decide to isolate. They found this worked well because the Tsimane already usually made their big decisions together as a community in special meetings and already had a tradition of quarantining new mothers. The Chapman scientists said their plan would also work for other indigenous peoples who also make decisions together, like the Tsimane. The Waswanipi Cree in Canada, the Mapoon people in Australia, and many groups in South America already tried plans like these on their own.
In May 2020, police officers in Minneapolis, Minnesota killed an unarmed black man called George Floyd while they were arresting him. There were weeks of protests all over the world against police brutality and racism. Experts said they were worried protesters and police could spread SARS-CoV-2 to each other. Other experts said some of the reasons that the protests were so big was because non-white people were being killed by COVID-19 more than white people were, because poor leadership in the COVID-19 crisis reminded them of poor leadership about racism, and because the lockdowns shut down workplaces and other things. This meant people had more time to protest.
African Americans are more likely to die from the virus.
In early 2020, some people began to think that the SARS-CoV-2 may have been made on purpose in a laboratory and either released by accident or on purpose like a weapon. Some Iranians thought the Americans might have made it. Chinese state media said COVID-19 came from the United States to China and not the other way around. Some Americans thought the Chinese might have made it. Some Britons thought it might have been created by accident by 5G cell phone networks.
On March 17, 2020, scientists from Columbia University and other places published a paper in Nature Medicine showing that SARS-CoV-2 was almost surely not made by humans in a laboratory. They did this by comparing the genomes of different viruses to each other. The scientists saw that SARS-CoV-2 did not match any of the viral backbones that already exist for virologists to use. Within a few weeks, it became one of the most cited scientific papers in history, meaning that other scientists were reading and using it.
Case fatality rates by age group in China. Data through 11 February 2020.
Epidemic curve of daily new cases of COVID-19 (7 day rolling average) by continent
Semi-log plot of weekly new cases of COVID-19 in the world and top five current countries (mean with deaths)
COVID-19 total cases per 100,000 population from selected countries
COVID-19 active cases per 100,000 population from selected countries
COVID-19 deaths per 100,000 population from selected countries
On December 31, 2019, China alerted WHO to several cases of unusual pneumonia in Wuhan, Hubei province.
On January 20, 2020, Chinese premier Li Keqiang called for efforts to stop and control the pneumonia epidemic caused by a novel coronavirus. As of February 5, 2020, 24,588 cases have been confirmed, including in every province-level division of China. A larger number of people may have been infected, but not detected (especially mild cases). The first local transmission of the virus outside China occurred in Vietnam between family members, while the first local transmission not involving family occurred in Germany, on January 22, when a German man contracted the disease from a Chinese business visitor at a meeting. As of 5 February 2020[update], 493 deaths have been attributed to the virus since the first confirmed death on January 9, with 990 recoveries. The first death outside China was reported in the Philippines, in a 44-year-old Chinese male on February 1. but another source reported: "The first cases of COVID-19 outside of China were identified on January 13 in Thailand and on January 16 in Japan".
There has been testing which have showed over 6000 confirmed cases in China, some of whom are healthcare workers.
Confirmed cases have also been reported in Thailand, South Korea, Japan, Taiwan, Macau, Hong Kong, the United States (Everett, Washington and Chicago), Singapore, Vietnam, France and Nepal.
The World Health Organization declared that this is a Public Health Emergency of International Concern since January 30, 2020.
Bloomberg News and other business publications have reported several plant closures, travel restrictions, and imposed quarantines as a result of this outbreak.
As of February 10, 2020 there have been 40,235 confirmed cases reported of people infected by the virus in China. Also reported were 909 deaths, and 319 cases in 24 other countries, including one death, according to WHO chief Tedros Adhanom Ghebreyesus.
On November 14, 2020, there were 53,853,718 global COVID-19 cases and 1,311,524 deaths with cases in 217 countries and territories.
The pandemic made it more difficult for millions of people all over the world to get enough food. People lost their jobs, so they did not have money to buy food. Farms were shut down, so there was less food made. Processing plants and food factories were shut down, so less food was made ready for people to eat.
In April, Arif Husain of the United Nations' World Food Program said that 130 million more people could go hungry, in addition to the 135 million who were already hungry before the pandemic began. He said that poorer countries would be more affected than rich countries because the way they move raw food from farms to cities and other places where people live is less organized and relies more on human beings than on automatic systems.
This hunger crisis is different from crises in other years because it happened to the whole world at the same time. That meant that people working in other countries could not help by sending money home.
All over the world, children who ate meals at school had less access to food when the schools were shut down.
Scientists from the University of Michigan said the pandemic was making it harder for people to find food. In a study published in May, they said out of of seven Americans over age 50 said they had trouble getting enough food before the pandemic, and it got worse when senior centers that provided meals were closed. Federal and state governments started programs to bring food to older people and children. There were also more food donation drives in towns.
In the United States, nursing homes had some of the highest rates of infection and death,
40% of all COVID-19 deaths in the country. Nursing homes are group homes for old people who need medical care, for disabled people who need medical care, and for people recovering from severe sickness or injury, like stroke patients.
Many people who live in nursing homes pay through the government program Medicaid, which pays less than Medicare or regular insurance companies. In June, many American nursing homes were caught throwing their regular patients out so they could make room for COVID-19 patients who could pay them more. Because nursing homes had stopped allowing visitors, it took longer for them to get caught. United States law requires nursing homes to warn patients 30 days before kicking them out, but the nursing homes did not do this.
Some of the nursing homes took the COVID-19 patients because state governments asked them to and they say they sent their elderly residents away because they were worried they would catch COVID-19 from the sick patients.
Because so many governments told people to stay at home, there was less air pollution than usual for that time of year. Pollution in New York fell by 50% and the use of coal in China fell by 40%. The European Space Agency showed pictures taken from a satellite of China's pollution disappearing during quarantine and coming back when everyone went back to work.
The pandemic and shutdowns made people use less electricity. In the United States, people got less of their electricity from coal power but kept using gas and renewable power like wind and solar power. This was because coal plants are more expensive to run, so power companies used them less.
Pollution from before the pandemic also affected what happened after people became sick. Scientists saw that more people died from COVID-19 in places with large amounts of air pollution. One team of scientists from Martin Luther University Halle-Wittenberg looked at air pollution information from satellites and statistics on COVID-19 deaths in Italy, France, Germany and Spain and saw that places with large amounts of nitrogen dioxide pollution had more people die from COVID-19. Nitrogen dioxide can damage the lungs.
The shutdowns and social distancing also affected animals. Human beings started staying at home about the same time in the spring when sea turtles like to come on land to lay their eggs. Turtle scientists in the United States and Thailand both reported more nests than usual on seashores in Florida and Phuket. They say it is because people are not coming to the beach or bringing their dogs to the beach and because there are fewer boats in the water nearby. Scientists also say they see more dugong and dolphins. With fewer cars driving down roads, salamanders, frogs, and other amphibians were able to cross them for their spring migration. According to citizen scientists from Big Night Maine, a group that watches amphibians, four amphibians made it across the roads alive for every one amphibian killed by cars. Most years, it is only two to one.
Not all ocean mammals did well. According to marine biologists in Florida, manatee deaths in April and May were 20% higher than in 2019. They say this was because many people decided to go boating because other things to do were closed.
Researchers from the San Diego Zoo Global had the idea for a system that people could use to find dangerous germs before they become pandemics or even before they jump from other animals to humans. They said it was important to watch the wildlife trade, like in the Wuhan wet market. The scientists said that over the past eleven years it has gotten easier and easier to sequence viral genomes, and it does not have to be done by a large lab or by a government any more. The scientists said it would be better to spread the work out among more people.
Avoiding traveling and staying home will greatly reduce your risk from catching COVID-19. Staying home doesn't apply if one is sick and needs medical care. Get enough rest and stay hydrated. Wearing a mask and washing your hands can prevent the virus from spreading. Masks should not be placed on children under 2 years of age, people who have trouble breathing, have a respiratory or other medical condition which renders one unable to wear a mask safely, or anyone who is unable to remove the mask without help. Covering coughs and sneezes also reduce the risk of spreading the virus, but one can infect someone else by touching things with coughed/sneezed-in hands. Making sure not to share drinking glasses, cups and particularly other objects which people will drink or eat out of is important if one assumes they are infected or tested positive in the past. Washing eating utensils and other oral eating objects is preferable and cleaning surfaces or possessions which have been repeatedly touched is also important. These include, according to the Centers For Disease Control and Prevention, phones, remote controls, counters, tabletops, doorknobs, bathroom fixtures, toilets, keyboards, tablets, and bedside tables. Avoiding touching your face, nose, or mouth with your hands. Avoiding public transportation, taxis or taking rides with others can stop one's exposure to the virus. Rumors spread about high doses of Vitamin C preventing COVID-19, but these as of October 14, 2020, there has been no conclusive evidence to support this idea. However, there has been evidence pointing to the fact that dosing patients with Vitamin C, either through mouth or IV can reduce time on mechanical ventilators for seriously ill patients by 14%.Drinking tea such as black tea and green tea can inhibit the virus. Staying home for the holidays, having a small gathering of close friends and family members who are consistently taking measures to reduce the spread of COVID-19 and celebrating virtually through social media can prevent being infected by the virus. Airports, bus stations, train stations, public transport, gas stations, and rest stops are all places travelers can be exposed to catching the virus. Eating a healthy diet that is high in fruits and vegetables, getting rest and sleep, exercising, consuming raw honey, probiotics, garlic, mushrooms and elderberry can boost the immune system. Playing video games to pass time during quarantine can prevent the virus from spreading. Flavanols and proanthocyanidins which are chemicals found in dark chocolate, grapes and green tea may block SARS-CoV-2 proteins. Places you are most likely to catch the virus are churches, hair and nail salons, cruise ships, hospitals and the doctor’s office, restaurants and bars, theaters, sporting events, concert venues, buses, restrooms, elevators, the gym, airplanes, hotels, public swimming pools, nightclubs and the beach.