Chapter 1 VIRUS ALERT In 2020 a deadly virus spread around the world The virus emerged in China at the end of 2019 Then international travelers carried it to other nations Scientists studied the virus to learn more about it They discovered it was a coronavirus a name that means crown virus 4
Each virus particle is covered by little spikes They look like points on a crown A team of international scientists gave the virus an official name SARS-CoV-2 but the media simply called it the coronavirus The virus caused a disease called COVID-19 The spikes on the coronavirus lock into cells in the human body 5
Most people who are infected with the coronavirus have mild symptoms such as coughs fevers and body aches They usually recover on their own at home Some people who got the virus didn’t get sick at all But others became extremely sick They had trouble breathing and needed hospital care Many of those patients died BECAUSE THE VIRUS ATTACKS THE LUNGS COUGHING IS A COMMON SYMPTOM OF COVID-19 6
STEM Spotlight A pandemic is a widespread outbreak of disease Pandemics have hit human society many times before One of the worst pandemics took place in 1918 and 1919 A deadly flu virus spread around the world At the time there was no flu vaccine Doctors then didn’t know much about viruses They did not have good medicines to treat the sick Worldwide the virus infected about 500 million people and killed at least 50 million In the United States the virus killed about 675,000 people 7
