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As of Sunday, Mar. 22, there are 50 confirmed cases of COVID-19 in Idaho. Three of the confirmed cases are from Canyon County. In addition, we have over 130 exposures to a confirmed case in Ada County who was at Middleton Middle School on March 11 and 12. SWDH is working to contact those who were potentially exposed and will be monitoring them for symptoms through Thursday, March 26.

Counties with confirmed cases include Ada (13), Bingham (2), Blaine (21), Canyon (3), Kootenai (3), Madison (1), Teton (2), and Twin Falls (1).

Community transmission has been determined in Blaine County. Our six-county region remains in “none to minimal” community transmission status.

SWDH’s Continuity of Operations Branch asked our Medical Director the following questions; his responses may be of benefit to your organizations.

1. How long does the virus stay alive on surfaces?

A new study from National Institutes of Health, CDC, UCLA, and Princeton University scientists in The New England Journal of Medicine demonstrated that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was detectable in aerosols for up to three hours, up to four hours on copper, up to 24 hours on cardboard, and up to two to three days on plastic and stainless steel.

2. How long is it alive in the air?

Per above, up to 3 hours as an aerosol in a room with poor/no air exchange.

3. Do temperatures affect it?

For the novel coronavirus SARS-CoV-2, we have reason to expect that like other beta coronaviruses, it may transmit somewhat more efficiently in winter (and dryer) than summer (more humid) weather, though we don’t know the mechanism(s) responsible. The size of the change is expected to be modest, and not enough to stop transmission on its own. Based on the analogy of pandemic flu, we expect that SARS-CoV-2, as a virus new to humans, will face less immunity and thus transmit more readily even outside of the winter season.

Coronaviruses as a family have various temperature sensitivities. Many are considered to thrive in ‘cold weather’ and decrease activity in ‘warm weather’ but this is not seen in all coronaviruses and cannot be applied to SARS-CoV-2.

4. What are the most effective sprays, wipes?

Use diluted household bleach solutions if appropriate for the surface. Check to ensure the product is not past its expiration date. Unexpired household bleach will be effective against coronaviruses when properly diluted. Follow manufacturer’s instructions for application and proper ventilation. Never mix household bleach with ammonia or any other cleanser.

To make a bleach solution, mix:

n 5 tablespoons (1/3rd cup) bleach per gallon of water


n 4 teaspoons bleach per quart of water

n Alcohol solutions with at least 70% alcohol.

Household cleaners and disinfectants: Clean the area or item with soap and water or another detergent if it is dirty. Then, use a household disinfectant. Follow the instructions on the label to ensure safe and effective use of the product.

Many products recommend:

n Keeping the surface wet for several minutes to ensure germs are killed.

n Precautions such as wearing gloves and making sure you have good ventilation during use of the product. Most EPA-registered household disinfectants should be effective.

5. Distance to stay between people?

Social distancing means remaining out of congregate settings, avoiding mass gatherings, and maintaining distance (approximately 6 feet or 2 meters) from others when possible.

Other resources:



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