Perhaps I can help answer your microbiology question which is really about SARS-CoV-2 which is an enveloped mRNA virus. There is a lot of misunderstanding about SARS-CoV-2 and the medical disease it causes, COVID-19. The confusion is understandable as this is a novel coronavirus with a high rate of transmission & people around the globe are still in a learning curve about it. It's important to understand how to decimate SARS-CoV-2 whenever possible. I'm an RDN & years ago I went to grad school on an Allied Health Traineeship thanks to citizens of the U.S.A. Although now retired, as well as having been a clinician, I'm a former prof. I believe in giving back to society which has supported me.
Many pieces in the press unfortunately use terms of SARS-CoV-2 and then COVID-19 interchangeably, which they should not. This adds to public confusion. Keep in mind that disinfection in this instance pertains to decimation of the virus SARS-CoV-2 per se.
Cleaning should precede disinfection. Disinfection is biocidal elimination on fomite surfaces of microorganisms, in this instance SARS-CoV-2. After applying disinfecting dilution be sure to allow it adequate action time and then allow surface to air dry.
When CDC says to use “5 tablespoons (aka 1/3 cup) bleach per gallon of water” or “4 teaspoons bleach per quart of water” that is in effect 1000 ppm. CDC guidance assumes household bleach concentration to be 5-6.25%, even though most NaOCl manufacturers int the U.S.A. went to 8.25% back around 2012-2013. Check any bottle you have (or box it came in) for the NaOCl concentration for that batch of bleach. When first manufactured concentration is higher, but over time actual available free chlorine level drops and adequate potency passed by 1 year out from manufacturing date. If stored at higher room temperature, cut that down to 6 months which is more realistic. Adequate 1000 ppm of NaOCl for enough time (minimum 1 minute) can kill SARS-CoV-2. If the non-porous fomite surface happens to be a countertop where inadvertently later food might be placed on, then after first cleaning, then disinfecting, be sure to rinse with potable H2O, then use a sanitizing solution dilution and allow to air dry.
See: "COVID-19 – Disinfecting with Bleach" from Michigan State U Center for Research on Ingredient Safety which will explain how to read date code of manufacturing on a household bleach (NaOCl) bottle and how much bleach to add to cold water in order to reach what is effectively a 1000 ppm dilution if bleach is still ‘fresh enough’ aka adequate concentration in bottle as purchased. The bleach concentration bottle code information can be read as follows (quoted or paraphrased from article):
Example: code E619337.
●First two characters E6 identify the company facility that manufactured the bleach.
●Second two numbers 19 tell the year the company manufactured the bleach.
●Last three numbers 337 tell the day of the year the company manufactured the bleach.
So, code E619337 tells us this bottle of bleach was manufactured at facility E6 in 2019 on the 337 day of the year (using a Julian calendar), which is December 3.
This bottle of bleach technically expires one year from December 3, 2019, so it needs to be used or disposed of by December 2, 2020.
Similarly a product code A420027 tells us the product was manufactured at facility A4 in 2020 on the 27 day of the year, which is January 27. The product expires one year from January 27, 2020, so it needs to be used or disposed of by January 26, 2021.
Adjust the Julian calendar keeping in mind the year as 2020 is a leap year.
From experience using test strips with bleach concentrate dilutions, often that expiration timeline is closer to 6 months (commercial settings open bottle only 1 month).
Public Health Ontario has an online "Chlorine Dilution Calculator" to help anyone determine how much NaOCl "household" bleach of a given concentration level to add to how much safe tap water to achieve a certain ppm of diluted chlorine sol'n. One can calculate sanitizing or even disinfecting diluted chlorine sol'n levels using the online calculator. Although the site is in Canada, they kindly include both English and Metric units. https://www.publichealthontario.ca/en/health-topics/environmental-occupational-health/water-quality/chlorine-dilution-calculator
Advisement of 1000 ppm for a NaOCl dilution based on publication:
Kampf, G. et al. Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents. Journal of Hospital Infection, Volume 104, Issue 3, 246 - 251 (March 2020). https://doi.org/10.1016/j.jhin.2020.01.022
Fomite transmission (contact w/ inanimate or nonpathogenic object surface transmission exclusive of food components) reduction via biocidal agents such as 0.1%-0.5% NaOCl aka 1000-5000 ppm. “...Human coronaviruses on inanimate
surfaces can be effectively inactivated by surface disinfection procedures with 62-71% ethanol, 0.5% hydrogen peroxide or 0.1% sodium hypochlorite within 1 minute.” from pre-print https://doi.org/10.1016/j.jhin.2020.01.022
Edit: The question is really about disinfecting for SARS-CoV-2, the mRNA virus which causes COVID-19 in humans.
The edit is to:
1) Clarify the actual question, which deals w/ microbiology relating to SARS-CoV-2, not a medical disease condition COVID-19;
2) Acknowledge that the press has incorrectly used the two different terms interchangeably creating public confusion & explain why many professionals are responding in forums around the world trying to clear up that confusion by providing accurate information;
3) Include current full rather than shortened links to details of NaOCl disinfection of SARS-CoV-2 with enough detail that if links are later unavailable readers will still know what to do.