Earth is always rotating around the sun that means if it were winter on one side of the world, (that is not on the side of the sun) the other side of the world would be summer, ( the side that the sun is shining on)
These preparations are called Vaccines. A vaccine is a biological preparation that provides active acquired immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing micro-organism and is often made from weakened or killed forms of the microbe, its toxins or one of its surface proteins.
Opportunistic infections are infections that occur more frequently and are more severe in people with weakened immune systems, including people with HIV.
