A recent report from the CDC from the US Centers for Disease Control and Prevention stated that Coronavirus RNA was found on the Diamond Princess ship 17 days after the passengers had vacated the premises-the news is making may question what the risks are when it comes to handling “high-touch” surfaces.
In conversation with The Guardian, Dr Akiko Iwasaki, professor of immunology at Yale University and Dr Julia Marcus, infectious disease epidemiologist and professor in the Department of Population Medicine at Harvard Medical School talk about how to handle groceries and packages, tips for cleaning surfaces and the chances of being contaminated via surfaces.
What do we need to know about the coronavirus RNA that was found on the Diamond Princess cruise ship 17 days after passengers left?
Dr Julia Marcus: A CDC investigation of the cruise ship found evidence of viral RNA in cabins that hadn’t yet been cleaned. But to be clear, that just means the virus was detectable – not that it was viable or that contact with those services would have been able to infect someone. (Editor’s note: RNA, or ribonucleic acid, carries the virus’s genetic information.) Dr Akiko Iwasaki: It just means that there are parts of the virus that still remain. The virus needs many other components to be intact. If you have bits and pieces of RNA, that’s not going to make a virus, you need an entire intact genome. Just because you had a little piece of RNA doesn’t mean that there’s an infection. Dr Julia Marcus: The New England Journal of Medicine just published a study that tested how long the virus can remain stable on different kinds of surfaces within a controlled laboratory setting. They found that it was still detectable on copper for up to four hours, on cardboard for up to 24 hours, and on plastic and steel for up to 72 hours. But it’s important to note that the amount of virus decreased rapidly over time on each of those surfaces. And so the risk of infection from touching them would probably decrease over time as well. Dr Akiko Iwasaki: There’s a certain amount of viral particle that you need to be exposed to become infected. If you just had one viral particle on your finger, it’s unlikely that you’re going to be infected. Some viruses are very potent, you only need like 10 particles to get infected, while others you [may] need millions. The fewer viral particles you’re exposed to, the less likely you’re going to get infected. That’s why the amount of virus on a surface is important.
How many people are being contaminated via surfaces as opposed to airborne particles or direct contact with an infected person?
Dr Julia Marcus: As far as we know right now, people are much more likely to be infected by close contact with an infected person than by touching a contaminated surface. That said, it’s still important to be conscious of what we’re touching, especially high-touch surfaces, and be careful about cleaning our hands after touching things. For example, public transit or grocery stores and places where there tend to be a lot of people. Dr Akiko Iwasaki: The virus is pretty stable on [materials] like plastic and steel – they can persist for a few days. So it’s very possible that someone who’s sick will deposit the virus on to the surface and then somebody else will touch it and touch their face.
Is there a risk of being infected by groceries and packages that we have delivered?
Dr Julia Marcus: It’s a low risk, but it’s possible that if someone is delivering a package to your house and they are sick, that may be a route for transmission. I would recommend that any time something new comes into your household, be conscious of washing your hands after handling it. Dr Akiko Iwasaki: The [virus’s] stability is pretty good on the cardboard. Once you get those packages, open them, quickly throw away the cardboard, wash your hands, and try to avoid touching your face. Take any measures that you can to minimize contact from the surface of the package to your face.
Is it possible the contents of a package could have been contaminated by whoever packed it?
Dr Akiko Iwasaki: There’s definitely a possibility of contamination, but it’s much more likely that the outer cardboard itself will come into contact with a lot more people than what’s inside. And if it takes days to get to your home, whatever virus that was inside will be deactivated already.
Do you have any tips for cleaning surfaces?
Dr Julia Marcus: It’s good to routinely clean any high-touch surfaces, like door handles and toilets. Regular household cleaners are effective, including bleach solutions and alcohol solutions of at least 70% alcohol. If somebody in your household has been diagnosed with Covid-19, then cleaning and disinfection becomes much more important and should be done more frequently. Dr Akiko Iwasaki: The [Food and Drug Administration] has a list of home cleaning products that are known to kill Covid-19. This virus is an enveloped virus so it doesn’t survive well in soap and alcohol. Read more from ProperGaanda: During a pandemic that has ravaged the world’s super powers, 4 countries are still safe