disinfect
The FDA disinfection is defined as:

"... through physical or chemical means to eliminate pathogenic and other types of microorganisms. Compared with sterilization, sterilization is less lethal because it can kill most recognized pathogenic microorganisms, but not necessarily destroy all microbial forms, such as Bacterial spores.

Bacterial spores are the main point of difference between disinfection and sterilization. Viruses do not reproduce through spores, which is one of the many reasons why work around the new coronavirus focuses on disinfection. The U.S. Institute of Health specifically pointed out this distinction and said that "disinfection and sterilization can both remove pathogens. The method to distinguish between these two technologies is endospores."

The CDC classifies disinfection as high, medium, and low-level disinfection based on the type of organism destroyed at each level. Sterilization is the highest level, which refers to the destruction of all potentially pathogenic organisms.

Like all coronaviruses, SARS-CoV-2 belongs to a subset of lipid viruses. Lipid viruses are single-stranded RNAs encapsulated in fatty membranes. Most chemicals considered to be disinfectants destroy the envelope and decompose RNA, making it easily inactivated by the lipid-encapsulated virus that is inactivated by microorganisms.

Intermediate disinfection refers to any procedure that can successfully destroy fungi and vegetative microorganisms (especially Mycobacterium tuberculosis that causes the disease of the same name in humans). Chemical disinfectants that reach this level usually carry the label "Mycobacterium tuberculosis".

, High-level disinfection refers to the process of destroying all microorganisms that destroy high concentrations of bacterial spores. Usually, EPA approved disinfectant chemicals are used for disinfection.

Sterilization
Unlike disinfection, the definition of sterilization is simpler. Sterilization refers to the process of destroying all microorganisms (including bacterial spores) that reach a specified level on an object or surface. The "specified level" is determined through a verification process using a biological indicator containing non-infectious bacterial spores. Since it is known to be difficult to inactivate, the spore Bacillus thermophilus is usually used to verify the sterilization effect. The biological indicator will contain a known population of these spores, for example 1,000,000 spores. If all these spores can be killed, the sterilization process is considered successful.

A common misunderstanding is that sterilization is binary, that is, whether the object is stable or unstable. In fact, sterilization is a statistical event. Only a certain degree of sterility can be ensured. The confidence factor is expressed as a probability measure called "Sterility Assurance Level" (SAL). SAL is written in the form of 10-n, the most common is 10 -6, which is 1 / 1,000,000 of the chance that a single microorganism will survive the sterilization process. This is also known as the "6 Log" reduction of living creatures.

By changing process parameters, SAL can be modified to meet various requirements. For the steam sterilization process, adding one or two main parameters (time and temperature) will increase SAL. Although the most common SAL is 10 -6, "overkill" methods may be used for processes that require high sterility. Overkill usually refers to a process where the target SAL is 10 -12. The purpose of overkill is to reduce the possibility of living organisms to such a low level that the risk is essentially zero.

When determining the process parameters for sterilization and validation, it is important to consider possible pathogens and the risks they pose. Historically, based on the 6 Log reduction of bacterial spores, the rule of thumb for steam sterilization is 15 minutes at 250°F. Recently, a new disease-causing microorganism called a virus has appeared. Ions viruses have attracted widespread medical attention because they are more resistant to common sterilization standards than bacterial spores.

Sterilization is the gold standard for microbial decontamination, but it can only be performed through approved procedures through approved sterilizing agents. Although steam is the most widely used disinfectant, there are many other methods available that rely on chemicals, radiation, and/or phases of matter. Material compatibility will usually tell you which biocide is the best choice for your application. Because of its low cost, short processing time and generally accepted by regulatory agencies.