Do you need to change your toothbrush after having an orgasm?

As more and more people are infected with the new coronavirus, many people are considering a question that has gradually changed from "what to do after a positive test result" to "what to do after a negative test result". For example, will there be traces of the new coronavirus on the original cosmetics and daily necessities? Especially lipsticks, lip balms, toothbrushes, cups, these personal items that come into contact with the mouth, do they need to be replaced?

In order to determine whether daily necessities need to be replaced after a positive test, we must first talk about how long the virus survives on the surface of objects .

01

How long can different strains of the new coronavirus survive on surfaces?

As early as the beginning of 2020, a research team from the National Institute of Allergy and Infectious Diseases and Princeton University published an article in the New England Journal of Medicine, which studied the survival time of the new coronavirus after it leaves the human body and spreads through aerosols or droplets to the surfaces of various daily necessities. Three years ago, the new coronavirus was still the original strain. This study showed that at the experimental temperature, the original strain can survive in the air for 3 hours , on the surface of paper items for 4-24 hours , on plastic and stainless steel for 2-3 days , and on glass for a longer time , up to 9 days .

An article published in the New England Journal of Medicine reveals the survival time of the original strain of the new coronavirus. Image source: Reference [1]

So this year, will the survival time of the new coronavirus, the Omicron strain, which has mutated so many times, change on the surface of objects?

There are indeed changes . From the original strain in early 2020 to the Alpha strain, to the Beta strain, the Gamma strain, the Delta strain, and finally to the current Omicron strain, as the new coronavirus continues to evolve, its transmissibility becomes stronger and stronger, which is related to the time they survive on various surfaces. The Omicron strain that is prevalent today can survive for a long time in the environment, which also "contributes" to the rapid spread of the epidemic.

So how long is this “long time”?

Earlier this year, a study by Kyoto Medical University in Japan showed that Omicron can survive on plastic surfaces for 193.5 hours, followed by the Alpha strain at 191.3 hours, the Beta strain, the Delta strain and the Gamma strain at 157 hours, 114 hours and 59 hours respectively, while the original strain from three years ago only survived for 56 hours.

They also studied the ability of different coronavirus strains to survive on human skin. The results showed that the Omicron strain had the longest survival time on the skin, at 21.1 hours, followed by the Alpha strain (19.6 hours) and the Beta strain (19.1 hours), and finally the Delta strain (16.8 hours), the Gamma strain (11.1) and the Original strain (8.6 hours).

In other words, Omicron's survival time in the environment is indeed longer than the original strain , but it is still only a few hours or days.

02

The coronavirus is least active on porous surfaces

Another study published in the journal Scientific Reports also studied the survival time of the Omicron strain on smooth and porous surfaces such as stainless steel, glass, printed paper and facial tissue. The results showed that Omicron had the highest survival rate on the glass surface, and viable viruses could still be found even after 7 days. On 100% cotton fabric, the survival rate of Omicron was greatly reduced within 4 hours, and no live virus was detected after 24 hours.

Virus survival time on different surfaces. Image source: Reference [3]

(A) stainless steel, (B) plastic, (C) nitrile gloves, (D) chemical protective gloves, (E) N95 masks, (F) N100 masks, (G) high-density polyethylene fiber, and (H) cotton

Although many scientists have studied the survival time of different virus strains on the surface of objects, the reasons that affect the survival of each strain in the environment are still unclear. One hypothesis suggests that the porosity of cotton fabrics increases the surface area for adsorption of inoculated droplets , which may enhance the degradation of the virus and thus reduce its activity .

03

So, can you get infected with the virus by touching the surface of objects?

If you just turned from "positive" to "negative" today, so you invite a group of friends who have not been infected with Omicron to your house to celebrate. In order to prevent your friends from being infected, would you choose to open the windows for ventilation or disinfect the surfaces of all objects in your home?

In fact, there is no need to wipe and disinfect the surface of daily necessities in the home . Although the Omicron strain will survive longer on the surface of objects, people are unlikely to be infected with Omicron by contacting the surface of objects. Aerosols and droplets are the main routes of transmission.

For example, if the virus is transmitted to your friend's hands through aerosols or droplets, and he happens to rub his eyes, the new coronavirus is likely to enter the human body through his eye mucosa, causing him to be infected.

Therefore, when you invite friends to your house for a "negative party", in order to prevent your friends from becoming "positive", it is more reliable to open the windows for ventilation !

04

Can viruses on daily necessities cause us to be infected again?

Let's assume that you have the flu instead of the coronavirus. After you recover from the flu, will you throw away your lipstick, toothbrush and other daily necessities that may contain traces of the flu virus?

Of course not!

Should I throw away my lipstick?

In the same way, when you recover from COVID-19, you don’t need to replace your daily necessities . On the one hand, as I just mentioned, the virus can survive on the surface of objects in an experimental environment for no more than 10 days.

On the other hand, even if the virus survives on the surface of an object for a few weeks and infects the human body again, it will not be a big deal because after infection, the human body will produce specific antibodies against the corresponding strains and variants. When the human body is exposed to the same virus again, the immune cells in the body can quickly produce antibodies and eliminate the virus.

A study in October 2021 showed that reinfection with the new coronavirus can occur as early as three months after infection. This "re-infection" is unlikely to be reinfected by the virus on one's daily necessities. If it is "re-infected" in a short period of time, it must be accidentally infected with another variant of the virus. This is the same as catching a cold several times in a winter.

Therefore, after the "yang pass", your lipstick, lip balm, toothbrush, and cup can all be used! Not to mention other daily necessities, there is no need to replace them, so don't worry too much.

References:

[1] Van Doremalen N, Bushmaker T, Morris DH, et al. Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1[J]. New England journal of medicine, 2020, 382(16): 1564-1567.

[2] Hirose R, Itoh Y, Ikegaya H, et al. Differences in environmental stability among SARS-CoV-2 variants of concern: Omicron has higher stability[J]. bioRxiv, 2022.

[3] Kasloff SB, Leung A, Strong JE, et al. Stability of SARS-CoV-2 on critical personal protective equipment[J]. Scientific reports, 2021, 11(1): 1-7.

[4] Riddell S, Goldie S, Hill A, et al. The effect of temperature on persistence of SARS-CoV-2 on common surfaces[J]. Virology journal, 2020, 17(1): 1-7.

[5] Wilson C. How quickly can you catch covid-19 again?[J]. 2022.

[6] Townsend JP, Hassler HB, Wang Z, et al. The durability of immunity against reinfection by SARS-CoV-2: a comparative evolutionary study[J]. The Lancet Microbe, 2021, 2(12): e666-e675.

[7] Stegger M, Edslev SM, Sieber RN, et al. Occurrence and significance of Omicron BA. 1 infection followed by BA. 2 reinfection[J]. medRxiv, 2022.

Author: Denovo

Review | Sun Siqing, Chief Physician, Department of Respiratory and Critical Care Medicine, Nanjing Second Hospital

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