Are reasonable because jeans is plural. "is" is used when there is a singular subject and "are" is used when there is a plural subject.
Answer:
H1N1 is a subtype of the influenza virus, which causes the illness commonly known as the flu.
The method of contagion is the same for all flu: the virus enters the human system through the respiratory tract, mainly affecting the respiratory system (lungs, but it can also affect the throat), generating infections in these organs, which can cause a series of symptoms such as cough, excessive mucus, fever and physical discomfort.
These symptoms are attacked through different antiviral drugs, since there are no really effective antibiotics against this common disease. This, added to the existence of vaccines, means that the severity of the disease is not so important. Therefore, the antivirals in question are limiting these symptoms until the human body's own defense system defeats the virus.
Now days NASA has been evolving and making new ways to keep our astronauts safe in space however we sometimes might wonder is space traveling really safe after all?
