A worker cleans seats in a movie theater as it prepares for a possible reopening after the government eased lockdown restrictions previously imposed in Chennai on October 8, 2020 due to the Covid-19 coronavirus. (Photo by Arun SANKAR / AFP) (Photo by)
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LONDON – The coronavirus can survive on surfaces like glass, steel, vinyl, paper and polymer banknotes for 28 days, Australian researchers said Monday, underscoring the importance of effective cleaning and hand washing to curb the spread of Covid-19.
The results of the Australian national science agency CSIRO showed that SARS-CoV-2 can survive on surfaces significantly longer than many expected.
The peer-reviewed study also found that the virus was "extremely robust" at lower temperatures and remained infectious longer compared to higher temperatures.
The researchers tested the survival rates of the virus, dried in an artificial mucus solution, at three temperatures on six common surfaces. However, all experiments were carried out in the dark as UV light has already been shown to kill the virus.
The coronavirus is mostly transmitted from person to person through small droplets from the nose or mouth that are expelled when an infected person coughs, sneezes or speaks.
However, the World Health Organization has also stated that it is possible to become infected if these droplets land on objects and surfaces that are touched by people, who can then touch their eyes, nose or mouth.
To protect themselves, the United Nations Health Department recommends that people keep a distance of at least 1 meter from other people and disinfect surfaces that are touched frequently. It is also recommended that you clean your hands thoroughly and frequently, avoiding touching your eyes, mouth, and nose.
Globally, more than 37.4 million people have become infected with the coronavirus, with 1.07 million people killed, according to Johns Hopkins University.
What were the results of the study?
CSIRO researchers tested SARS-CoV-2 on multiple surfaces at 20 degrees Celsius, 30 degrees Celsius and 40 degrees Celsius, with the relative humidity being kept at 50%. The surfaces used in the study were stainless steel, glass, vinyl, paper, and polymer banknotes, and cotton cloth.
A drop of liquid containing the virus at concentrations similar to those seen in infected patients was dried on several small test surfaces and left for up to 28 days, the researchers said.
The study published in the Virology Journal found that the virus survived for 28 days on smooth surfaces such as stainless steel, glass, vinyl, and paper-polymer banknotes when kept at 20 degrees Celsius (68 F), which is roughly room temperature. and in the dark.
The study does not detail whether SARS-CoV-2 RNA or the live virus was identified on the surfaces. CNBC has asked the authors to comment.
The virus was no longer infectious on some surfaces within 24 hours when tested at 40 degrees Celsius. At 30 degrees Celsius (80 F), virus viability dropped to three days on cotton and vinyl and seven days on glass, steel, and polymer banknotes.
A worker cleans the classes in preparation for school before teaching in person in specific classes at Taybe Schools in Khan Yunis, Gaza, October 4, 2020 on October 10, 2020.
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"These results show that SARS-CoV-2 can remain infectious significantly longer than is generally believed possible," the authors of the study say. Further research into the number of virus particles that can cause infection was still needed.
The researchers said that the question of whether virus particles on a surface could infect someone depends on several conditions, and that the time it takes viruses to inactivate naturally also depends on many factors.
"The makeup of the virus itself, the type of surface it's on, and whether the virus is liquid or dried can all affect its lifespan. Environmental conditions like temperature, sunlight and humidity also play a role," they said.
A previous laboratory test published in The Lancet Medical Journal found that SARS-CoV-2 can survive for three days on banknotes and glass and up to six days on plastic and stainless steel.
In comparison, the influenza A virus was found to survive on surfaces for 17 days.