Using heat to kill SARS‐CoV‐2

This article is being made freely available through PubMed Central as part of the COVID-19 public health emergency response. It can be used for unrestricted inquiry re-use and analysis in any form or by any means with acknowledgment of the original generator, for the duration of the populace health emergency. The current coronavirus pandemic has reached ball-shaped proportions and requires alone corporate and individual efforts to slow its spread. One critically important write out is the proper sterilization of forcible objects that have been contaminated by the virus. here, we review the presently existing literature on thermal deactivation of coronavirus ( SARS‐CoV‐2 ) and portray preliminary guideless on temperatures and photograph durations required to sterilize. We besides compare these temperatures/exposure durations with potential family appliances that may be thought able of performing sterilization .

1. INTRODUCTION

As societies put themselves into volunteer or enforce isolation, large populations of people are experiencing reduced contact with others in populace. When people venture into public, they are often donning masks ( homemade or industrially produced ) or other protective invest. Upon returning to isolation, masks and other invest should be treated as contaminated with virus. How should masks, invest, and other items be treated ? In many instances, plainly setting items aside for a long enough period of prison term will kill the virus. however, the command durations are not known absolutely, and surely depend on the type of airfoil. 1, 2, 3, 4, 5 Some invest types, for example, are identical able of retaining moisture and consequently, this affects the survival of virus contained therein. The general consensus is that viruses can survive up to a few days in clothing. It is reasonable to expect a exchangeable survival duration for viruses on/in protective face masks. That is, pollute masks can be treated by merely setting them aside for some needed duration until the viruses die. But to our best cognition, there is no scientific discipline on the command duration, and any needed duration would depend on the materials that form the mask. For example, waver fibers differ from non‐woven polymeric filter media. Mask users can apply sanitizing chemicals ( such as alcohol ) but it is not net whether this character of sanitizing would adversely affect the holey structure of masks and thereby make them less effective over clock time. similarly, there is no stream advice available for the manipulation of heat to destroy SARS‐CoV‐2.

here, we summarize all the existing temperature/duration information for both SARS‐CoV‐2 and its sensitivity to heat. The compendious is used to provide a fair recommendation for users to thermally destroy viruses on masks, invest, or other objects .

1.1. Summary of the existing literature

An example of the state of cognition on temperatures and coronavirus survival is provided by the CDC, which states : “ Generally coronaviruses survive for shorter periods at higher temperatures and higher humidity than in cooler or dryer environments. however, we do n’t have directly data for this virus, nor do we have direct data for a temperature‐based cutoff for inactivation at this point. The necessary temperature would besides be based on the materials of the surface, the environment, etc. ”. 6 But despite official statements such as the above, there is, in fact, some literature on the temperature and exposure durations that are required to inactivate SARS‐CoV‐2. In the stick to, a list of temperature/duration/inactivation rates is provided for coronavirus pathogens. In the number, we report logarithm reductions in viral load obtained from the references. In some studies, the inflame protocol was such that no viral bearing was detected afterwards. We have substituted an equivalent log reduction of 7 for these cases. Of course, the actual log reduction would be based on the sensitivity of the measurement instruments ; however, for practical purposes, we consider a viral reduction of 7 or greater to be at or near full sterilization. In Table, we present this literature information. We note that there are differences in the strains and media in which the virus was cultivated. We besides acknowledge that there are different thermal sensitivities for differing strains. It is far known that the media can affect the viral survival. For example, media with protein subject make the virus more repellent to heating. With this acknowledged, we opt to not provide classify psychoanalysis for different strains or media. preferably, our captive is to provide a one thermal recommendation that can be used to sterilize a broad rate of materials .

TABLE 1

Temperature (°C, °F) Duration (minutes) Log reduction Virus References
56, 133 10 5 SARS‐CoV (Urbani strain) 9
56, 133 20 6 SARS‐CoV (Urbani strain) 9
65, 149 3 6 SARS‐CoV (Urbani strain) 9
75, 167 15 7 SARS‐CoV (Urbani strain) 9
55, 131 120 5 Gastroenteritis coronavirus 10
56, 133 60 7 Canine coronavirus 11
65, 149 40 7 Canine coronavirus 11
75, 167 15 7 Canine coronavirus 11
56, 133 50 5 Canine coronavirus 11
65, 149 5 5 Canine coronavirus 11
75, 167 4 5 Canine coronavirus 11
56, 133 30 >5 SARS CoV, FFM1 no protein 12
50, 122 30 1.9 SARS, CoV, FFM1 With 20% protein 12
60, 140 30 >5 SARS CoV, FFM1 no protein 12
60, 140 30 >5 SARS, CoV, FFM1 With 20% protein 12
56, 133 5 5.8 SARS CoV (Hanoi strain) 13
56, 133 10 6.5 SARS CoV (Hanoi strain) 13
56, 133 30 >6.4 SARS CoV (Hanoi strain) 13
56, 133 30 2–5 SARS CoV (FFM1 strain) 13
56, 133 20 >4.3 SARS CoV (Urbani strain) 13
60, 140 30 >5 SARS CoV (FFM1 strain) 13
60, 140 30 >4 SARS CoV (FFM1 strain) 13
60, 140 60 >4 SARS CoV (FFM1 strain) 13
65, 149 10 >4.3 SARS CoV (Urbani strain) 13

Open in a separate window What is seen from these tabulations is that the independent studies are mutually reinforcing. The results from table can be used to formulate general guidelines for the public .

1.2. Recommendations for thermally destroying coronavirus

We provide a reasonable estimate for near complete thermal destruction of coronavirus. For temperatures above 65°C ( 149°F ) is expected to cause near complete deactivation with exposures greater than 3 minutes. For temperatures between 55 and 60°C ( 131‐140°F ) inflame should stopping point 5 minutes or more. however, for temperatures in the rate 50‐55°C ( 122‐131°F ) we recommend 20 minutes or longer of exposure. At these levels, we expect the viral concentration to be lowered by log 5‐7, near or below the detectable terminus ad quem.

Because of the seriousness of the stream coronavirus infection, we suggest a reasonable safety factor can be obtained by increasing the above‐listed temperatures by 10°C ( about 18 °F ). extensive inquiry has confirmed that at least for support cells, the sensitivity of thermal destruction is very powerfully linked to temperature. That is, small increases in temperature campaign large increases in the death rate. As an case, for mammalian cells and other pathogens ( bacteria, viruses, and protozoan ) the death rate rises quickly as temperature increases. 7, 8 Another reason for using a guard divisor is that the temperatures experienced by the virus during heating will not inevitably equal the temperature of the give hotness. Thermal inactiveness causes a heating system lag that depends, in separate, on the media being heated. With this conservative approach path, the follow become the recommendations : In order to kill COVID‐19, heat virus‐containing objects for :

  • 3 minutes at temperature above 75°C ( 160°F ) .
  • 5 minutes for temperatures above 65°C ( 149°F ) .
  • 20 minutes for temperatures above 60°C ( 140°F ) .

It should be noted that these findings agree with WHO guidelines which report a 4 log reduction of coronavirus for 56°C ( 133°F ) with 15‐minute exposures 14 and is consistent with information for killing other infectious agents. 15 These recommendations are hotter than encountered in residential clothes dryers, clothes washing machines, and serve washers. For these appliances, temperatures are typically at or below 57°C ( 135°F ). These temperatures are besides much hotter than residential hot water ( in the United States ), for example, plumbing codes limit hot water to 49°C ( 120°F ). Of course, since soap has some viricide characteristics, washing with soap is expected to inactivate viruses by nonthermal means .