If diffusing in your home, please ensure pets have access to other areas of the home.  Humans can deal with the scents, not all pets can.
Best Defense is my personal version of Thieves/On Guard.  An organic essential oil blend with a multitude of uses.....
Diffuse 15-20 drops of Best Defense Oil for 15 minutes three or four time a day in an essential oil diffuser. This can help freshen the air while adding a nice fragrance. As your family breathes in the oils it will help to support healthy lung, sinus and respiratory functions.
Washing your hands frequently with soap and water is good practice for stopping the spread of germs.
If you want additional immune support we run the diffuser continuously for a few hours.   
Adding a few additional drops of Lemon Essential Oil along with the Best Defense Oil in the diffuser to give extra support for healthy lung and sinus functions. 
Run the diffuser in the bedroom, at night, for anyone who could benefit from extra support. This gets a continuous flow of the oils into the lungs and sinuses. It can help relax, calm, and support a good night's sleep.
The Historical Story of the Four Thieves
The thieves were actually spice traders and merchants who imported spices, including cinnamon and clove from India. When the Black Plague hit, all international shipping and trade was closed down. Unable to do business, these spice traders quickly ran out of money and had to find a way to support themselves.
Since people in the communities were afraid to touch the dead bodies, they decided to loot the homes and bodies of the plaque victims. They would take clothes, jewelry, pots and pans, and then barter or trade them for food and money. They believed they wouldn't get sick if they rubbed vinegar, oils, and certain spices all over their bodies.
They were able to set up a very lucrative pawn business. Until the King found out…
When the King heard about the story of the thieves he wanted to know their secret recipe.
He sent his Constables out to capture them. Four of the thieves were caught and brought before the King. He gave them a choice to either share their secret formula of "immunity" or be burned at the stake. The four thieves decided to share their secret formula with the King.
The King immediately posted the thieves secret formula all over the town.
Hence the story of the four thieves.
There is an account of the Thieves Story recorded in the Royal English Archives.
Best Defense Oil Recipes for Household Use:
Stuffed Animals- Place toy inside pillowcase and tie shut. Fill washer with detergent, use fabric softener if desired. Add 5-10 drops of Best Defense Essential Oil, (for small load) to washing machine. Wash on gentle cycle.
Hair spray buildup, gum, gummy adhesive- Dilute 8 drops in 4 ounces of water, spray, let set for a few minutes before wiping.
Cell phones- Spray Best Defense cleaning solution very lightly on a cloth and gently wipe phone.
Dishwasher- Add 4-5 drops Best Defense oil to help clean dishes, eliminate build up and freshen odors.
Laundry- Add 5-6 drops per load to clean and freshen.
Pet Bedding- Spray down cat boxes, dog houses, and pet cages to clean and freshen.
Pet Dishes- Add 1-2 drops to soapy water and wash dishes. Rinse well.
 
Plants- For aphids spray plants with a mixture of 2 drops Best Defense oil to every 4 ounces of water.
Floors- Add 10-15 drops to ½ bucket of cleaning water.
Surfaces- To clean surfaces: add 8-16 drops to 8 oz. of water in spray bottle.
Fragrance- Add a few drops to potpourri or cinnamon sticks to fragrance your home.
Freshen the air- Add several drops of oil onto a cotton ball and place in home, office, car, or hotel air vents.
Freshen laundry- Drop 4–5 drops onto a cloth and place in clothes dryer.
Children’s Toys- Add 4-5 drops to sink water with a few drops of dish soap and wash children's toys.