Coronavirus does not spread easily through contaminated surfaces or objects, say updated CDC guidelines
The advisory comes even as a new study has found that presymptomatic patients have high viral load shedding and can easily contaminate environments. Researchers detected SARS-CoV-2 RNA on 8 (36%) of 22 surfaces, as well as on the pillow cover, sheet, and duvet cover used by these patients.
The new coronavirus spreads easily between people, but it "does not spread easily" from touching surfaces or objects, according to updated guidelines by the US Centers for Disease Control and Prevention (CDC). The CDC says that while scientists and health experts are still learning about how the virus spreads and the severity of the illness it causes, SARS-CoV-2, the virus that causes Covid-19, is spreading very easily and sustainably between people. The guidance on "How Covid-19 spreads", clarifies what sources are not major risks.
Under the heading — the virus does not spread easily in other ways — the document says that while it may be possible for Covid-19 to spread in other ways, "these are not thought to be the main ways the virus spreads", such as from touching surfaces or objects. "It may be possible that a person can get Covid-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes. This is not thought to be the main way the virus spreads, but we are still learning more about this virus," it says.
As far as animal to human transmission is concerned, the CDC says that at this time, such a risk is considered to be low. On people to animal spread, the guidelines say, "It appears that the virus can spread from people to animals in some situations. CDC is aware of a small number of pets worldwide, including cats and dogs, reported to be infected with the virus that causes Covid-19, mostly after close contact with people with Covid-19."
The document also says that information from the ongoing Covid-19 pandemic suggests that this virus is spreading more efficiently than influenza, but not as efficiently as measles, which is highly contagious. "The virus is thought to spread mainly from person-to-person: Between people who are in close contact with one another (within about 6 feet) and through respiratory droplets produced when an infected person coughs, sneezes or talks. These droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs. Covid-19 may be spread by people who are not showing symptoms," say experts.
The changes were made to the CDC website, without any explanation or formal announcement. It does not clarify what studies or new data the CDC may have consulted before updating its guidelines. CDC spokesperson Kristen Nordlund told NBC News the change was made during an internal review of its website and was meant to "clarify other types of spread beyond person to person." The advisory, however, continues to recommend routine cleaning and disinfecting of frequently touched surfaces, besides maintaining good social distance (about 6 feet) and washing hands to avoid being exposed to this virus.
Previous CDC guidelines on how the new coronavirus spreads said that Covid-19 is primarily spread from person to person, and one can become infected from respiratory droplets when an infected person coughs, sneezes, or talks. It said that a person may also be able to get it by touching a surface or object that has the virus on it, and then by touching the mouth, nose or eyes.
An earlier study, which was conducted by scientists from the CDC, the National Institutes of Health (NIH), UCLA, and Princeton University, found that SARS-CoV-2 could be detected 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. The results provide key information about the stability of SARS-CoV-2, which causes the Covid-19 disease, and suggests that people may acquire the virus through the air and after touching contaminated objects, the team had said back then.
"In contrast to SARS-CoV-1, most secondary cases of virus transmission of SARS-CoV-2 appear to be occurring in community settings rather than healthcare settings. However, healthcare settings are also vulnerable to the introduction and spread of SARS-CoV-2, and the stability of SARS-CoV-2 in aerosols and on surfaces likely contributes to the transmission of the virus in healthcare settings," said the study.
"The findings affirm the guidance from public health professionals to use precautions similar to those for influenza and other respiratory viruses to prevent the spread of SARS-CoV-2. This includes avoiding close contact with people who are sick, avoiding touching your eyes, nose, and mouth, covering your cough or sneeze with a tissue, then throwing the tissue in the trash, and cleaning and disinfecting frequently touched objects and surfaces using a regular household cleaning spray or wipe," experts had recommended.
Can Covid-19 spread through pillow covers?
Meanwhile, a new study has found that people who are infected with the coronavirus but do not show symptoms yet could spread the virus to a range of surfaces in a hotel room, including pillowcases, sheets and duvets. According to the research team from China, the findings reaffirm the potential role of surface contamination in the transmission of SARS-CoV-2 and the importance of strict surface hygiene practices, including linens of SARS-CoV-2 patients.
Two Chinese students studying overseas returned to China on March 19 (patient A) and March 20 (patient B). On the day of their arrival in China, neither had a fever or clinical symptoms, and they were transferred to a hotel for a 14-day quarantine. During the quarantine period, the local medical staff was to monitor their body temperature and symptoms each morning and afternoon. On the morning of the second day of the quarantine, they had no fever or symptoms. At the same time their temperatures were taken, throat swab samples were collected; both tested positive for SARS-CoV-2 RNA. The students were transferred to a local hospital for treatment.
Approximately 3 hours after the 2 patients were identified as positive for SARS-CoV-2 RNA, the team sampled the environmental surfaces of the two rooms in the centralized quarantine hotel in which they had stayed. The researchers found that presymptomatic patients have high viral load shedding and can easily contaminate environments.
"Our study demonstrates extensive environmental contamination of SARS-CoV-2 RNA in a relatively short time (less than 24 hours) in occupied rooms of 2 presymptomatic persons. We also detected SARS-CoV-2 RNA on 8 (36%) of 22 surfaces, as well as on the pillow cover, sheet, and duvet cover," says the team in their findings published in Emerging Infectious Diseases, an open-access, peer-reviewed journal published by the CDC.
They add, "The detection of SARS-CoV-2 RNA in the surface samples of the sheet, duvet cover, and pillow cover highlights the importance of proper handling procedures when changing or laundering used linens of SARS-CoV-2 patients. Thus, to minimize the possibility of dispersing virus through the air, we recommend that used linens not be shaken upon removal and that laundered items be thoroughly cleaned and dried to prevent additional spread."