A coronavirus is one of a number of viruses that cause diseases in mammals and birds. In humans, the viruses cause respiratory infections, including the common cold, which are typically mild, though rarer forms such as SARS, MERS and COVID-19 can be lethal. Symptoms vary in other species: in chickens, they cause an upper respiratory disease, while in cows and pigs coronaviruses cause diarrhea. There are no vaccines or antiviral drugs to prevent or treat human coronavirus infections.
Coronaviruses comprise the subfamily Orthocoronavirinae in the family Coronaviridae, in the order Nidovirales.[5][6] They are enveloped viruses with a positive-sense single-stranded RNA genome and a nucleocapsid of helical symmetry. The genome size of coronaviruses ranges from approximately 26 to 32 kilobases, the largest among known RNA viruses. The name coronavirus is derived from the Latin corona, meaning "crown" or "halo", which refers to the characteristic appearance of the virus particles (virions): they have a fringe reminiscent of a crown or of a solar corona.
In 2019, an outbreak began in Wuhan, China, and is ongoing as of February 2020. As of 15 February it has affected over 66,000 people. Because of the virus's contagiousness, mortality rate, and resistance to treatment, it has prompted extensive government action including mandated quarantines. Internationally, countries have limited travel to and from affected regions and implemented screening measures to detect potential carriers of the virus.
A coronavirus is one of a number of viruses that cause diseases in mammals and birds. In humans, the viruses cause respiratory infections, including the common cold, which are typically mild, though rarer forms such as SARS, MERS and COVID-19 can be lethal. Symptoms vary in other species: in chickens, they cause an upper respiratory disease, while in cows and pigs coronaviruses cause diarrhea. There are no vaccines or antiviral drugs to prevent or treat human coronavirus infections.
Coronaviruses comprise the subfamily Orthocoronavirinae in the family Coronaviridae, in the order Nidovirales.[5][6] They are enveloped viruses with a positive-sense single-stranded RNA genome and a nucleocapsid of helical symmetry. The genome size of coronaviruses ranges from approximately 26 to 32 kilobases, the largest among known RNA viruses. The name coronavirus is derived from the Latin corona, meaning "crown" or "halo", which refers to the characteristic appearance of the virus particles (virions): they have a fringe reminiscent of a crown or of a solar corona.
In 2019, an outbreak began in Wuhan, China, and is ongoing as of February 2020. As of 15 February it has affected over 66,000 people. Because of the virus's contagiousness, mortality rate, and resistance to treatment, it has prompted extensive government action including mandated quarantines. Internationally, countries have limited travel to and from affected regions and implemented screening measures to detect potential carriers of the virus.
1 read
I didn't read the newspaper this morning.
Did I read the newspaper this morning?
2 visited
We didn't visit her parents last month.
Did we visit her parents last month?
3 wanted
They didn't want to read this book last year.
Did they want to read this book last year?
4 watched
The didn't watch TV this night.
Did they watch TV this night?
5 saw
She didn't see him last year.
Did she see him last year?
6 ran
The didn't run this morning.
Did the run this morning?
7 stayed
Marina didn't stay at home yesterday evening.
Did Marina stay at home yesterday evening?
8 paid
He didn't pay by credit card yesterday.
Did he pay by credit card yesterday?
9 happened
It didn't happen last summer.
Did it happen last summer?
10 won
I didn't win last night.
Did I win last night?