Yes, but some viruses are more harmful than others.
it can be harmful but we have antibiotics so they aren't as harmful as some viruses.
Some viruses target harmful organisms. For example, bacteriophage viruses kill bacteria. Other viruses might kill mosquitoes or weevils or other harmful insects without hurting any other species.
Harmful chemicals or viruses that can be transferred from a mother to her developing fetus are called teratogens.
Antibodies
No. some viruses like the Bacteriophage ,instead of infecting us, infect the bacteria and devour it. This is a bacteriophage.
As harmful as the other viruses. You need to turn off your system restore and turn it back on .
Computer viruses have been known to cause millions of dollars worth of damage.
Biological Warfare
They can cause death and other diseases
Viruses can reproduce very quickly. When reproducing they enter a living cell and they inject their genetic material.
Harmful microbes are germs ,they cause various diseases i.e Bacteria,fungi,protozoa & viruses etc