Medical experts from HKU Li Ka Shing Faculty of Medicine such as Professor Ivan Hung have prepared useful health tips and precaution tips to keep us healthy during the outbreak of COVID-19.

How long does it take until the coronavirus loses its infectivity?

Q1. Are higher temperatures more likely to cause loss of infectivity in viruses?

Common knowledge says higher temperature are generally not ideal for viruses; our study further examines how different temperatures can have varying effects on the amount of time it takes for the virus to lose its infectivity. To test this hypothesis, our team incubated the virus and observed how long it would take for it to lose infectivity at different temperatures.

■ At 4°C, the virus remained stable after 14 days
■ At 22°C, the virus lost infectivity after 14 days
■ At 37°C, the virus lost infectivity after 2 days
■ At 56°C, the virus lost infectivity after 30 minutes
■ At 70°C, the virus lost infectivity after 5 minutes

For those concerned about having exposed their clothes to the virus (i.e. you had come in contact with a confirmed patient), or if you are taking care of someone currently under self-quarantine, you may want to first soak your clothes in hot water (60°C) f or 30 minutes before washing them in order to thoroughly disinfect.

Q2. Do different surfaces have an effect on the amount of time it takes for viruses to lose infectivity?

In addition to testing the impact of temperature on the infectivity of the virus, our team also tested how long it would take for the virus to lose infectivity on different surfaces. In summary, it seems the virus took a longer period of time to lose infectivity while on smoother surfaces, and less time on coarser ones:

■ Printed paper and tissue paper: the virus lost infectivity after three hours.
■ Wooden surfaces and fabric: the virus lost infectivity after two days.
■ Glass surfaces: the virus lost infectivity after 4 days.
■ Stainless steel surfaces and plastic: the virus lost infectivity after 4 to 7 days.
■ Surgical mask: the virus still detectable after 7 days

It is worth noting that the outer layer of surgical masks told a different story, as the virus remained infective and detectable even after 7 days. Knowing this, we once again stress that face masks should not be re-used; one should also wash their hands thoroughly before and after putting on the mask.

Q3. Are disinfectants effective in causing viruses to lose infectivity?

Although the coronavirus may take longer to lose infectivity when under room temperature, disinfectants may be used to shorten this duration, thereby reducing chances of transmission and infection. Our team tested a wide variety of different disinfectants and found that all the following were effective in causing viruses to lose infectivity after five minutes of use:

■ Household Bleach (1:49)
■ Household Bleach (1:99)
■ Ethanol (70%)
■ Povidone-iodine (7.5%)
■ Chloroxylenol (0.05%)
■ Chlorhexidine (0.05%)
■ Benzalkonium chloride (0.1%)

One point of note in the study: when hand soap was used at a ratio of 1:49, only half the number of the virus lost infectivity after five minutes; after 15 minutes however, all traces of the virus had lost its infectivity.

Read more:

Social Distancing DOs and DON'Ts

(Watch a video by HKUMED here.)

Distancing measures to reduce face-to-face interaction between people can help reduce the transmission of COVID-19, and has been a recommended precautionary measure by WHO. That being said, how can we carry out physical distancing in our daily lives? And how do we maintain routines that pertain to basic life necessities?

Q1. Can I go meet up with friends at restaurants? What about house parties?

We do not recommend social gatherings of any scale, whether it be at a crowded restaurant, a small house party, or even play dates. Close contact of any kind will increase the risk of infection and viral spread.

We must remember that those aged 70 years or above are three times more likely to be infected, and three times more likely to suffer fatal consequences; stay social with your loved ones through video chats, text messages, or even just phone calls. That is the best way to protect them.

Q2. I have scheduled appointments at the salon and beauty centre; can I still go?

We recommend postponing any non-essential appointments during this high-risk period until after the outbreak has subsided. In particular, salons and beauty centres often require long periods of close contact with service providers, increasing the risk of transmission and subsequent infection.

Q3. I’m getting really bored at home. Can we at least go to cinemas if seated in alternate rows?

Cinemas and other entertainment venues are all confined spaces where you are required to remain inside for extended periods of time with others; this of course has its associated health risks during times of an outbreak. We recommend instead to stay at home and stream your favorite movie or TV shows.

Q4. I can’t bear staying indoors all day. Can I at least go out to exercise?

Keeping a regular exercising routine is crucial for staying healthy. We recommend exploring workouts at home (such as stretching exercises, resistance training, yoga, etc), or doing cardio exercises in open-air areas where crowds are sparse. If you are outdoors, make sure to also maintain at least 3ft distance from others.

Bear in mind that physical distancing does not equate to social isolation. During these extraordinary times, both our physical and mental well-being can be affected; our social networks form an important support system, and should be maintained via virtual communications. Stay in touch with your friends and loved ones, as we face this outbreak together!

Health Precautions at the Workplace

With numerous confirmed cases of the COVID-19 stemming from group interactions, the most effective course of prevention is of course to stay home and minimise social contact. However, many of those in the work force may still be required to head out for work. The School of Public Health at HKU has suggested some health precautions and suggestions for those in the work force, covering potential areas of risk starting from when you head out to work, to when you return home.

Check out tips from HKU medical experts to protect yourself and minimise risks of infection!

Going to work:
◾Work from home if conditions permit
◾Staggered work schedules to avoid crowds
◾Wear a mask on public transportation
◾Minimise and shorten face-to-face meetings

While at work:
◾Maintain good indoor airflow
◾Place work spaces further apart to keep distance
◾Disinfect daily items such as keyboard, mouse, and mobile phone

During lunch:
◾Wash your hands before taking off your face mask, and handle it properly before eating
◾Enforce a staggered lunch schedule; buy takeaway meals or meal prep, and avoid going out
◾Avoid chatting while eating
◾Minimise face-to-face meals and use of round tables, and keep your distance from one another
◾Order individual portions of food and avoid sharing meals

Getting home:
◾Wash your hands and your work clothes after getting home
◾Avoid touching your nose and mouth after touching the door knob
◾Disinfect household items such as the door knob, toilet seat and basin, remote controls, and water tap handles etc.

Most importantly, if you are feeling unwell or experiencing any symptoms, avoid going to work and stay home in order to minimise chances of infecting others.

Stay healthy and stay well!

Outbreak precautions: thorough disinfection

Apart from droplets transmission, the new coronavirus can infect us through the conjunctiva in our eyes as well. As means of protection, we recommend putting on glasses to protect your eyes, as well as cleaning your belongings frequently to minimise the chances of getting infected. Professor Ivan Hung, Clinical Professor & Chief, Division of Infectious Diseases of HKUMed, is here today to introduce to everyone proper methods of maintaining the hygiene of personal everyday items.

Question: How should you clean your glasses?

Answer: Clean your glasses while washing your hands. Rub your hands with soap to create foam, and wash your glasses with it. Rinse the glasses with water afterwards.

Question: How should you clean your phone?

Answer: Spray hand sanitiser on a piece of tissue or cleaning cloth and clean the surface of the phone, the case and also the screen protector. Wipe the phone dry with a piece of tissue or cloth.

Question: Should we sanitise other clothing items, such as clothes, jackets, handbag and shoes?

◾Jacket: Wipe with wet cloth/ Put a piece of wet cloth on the jacket and iron it with high temperature/ Dry it under the sun.
◾Clothes: If the base or inner layers of clothing under your outerwear are not exposed to environments with an abundance of germs (i.e. clinics, hospitals or kindergartens), the chances of contamination are quite low. Doing laundry daily is recommended.
◾Handbag: Clean it with a piece of wet cloth.
◾Shoes: Take off your shoes before stepping into your home, and spray rubbing alcohol on the sole/ Wash the sole with soap and water/ Place a towel soaked with 1:99 diluted bleach at the entrance and step on it to sanitise your shoes.

Surgical Masks Demyth

Due to the recent outbreak of the coronavirus, surgical masks have been in high demand. "Should I make my own masks if I don't have enough at home?" We have been asked lots of questions regarding surgical masks lately.

Professor Ivan Hung from HKU Li Ka Shing Faculty of Medicine has prepared a set of Q&As specifically on the use of surgical masks. Check them out below and share with others! Always remember - sharing is caring. Stay alert and vigilant everyone! Stay strong and hang in there, we are all in this together!

Question: Are DIY masks better than nothing at all?

Answer: DIY masks can help reduce the amount of microbes expelled from a cough or a sneeze, but its effectiveness is only 1/3 of a surgical mask. 

Question: Are there any store-bought mask filters or materials that we can use to protect ourselves?

Answer: In short, no - the three layers each have specialised uses and cannot be bought in stores, while filters derived from other household items would obstruct breathing. 

Question: Is it possible to protect yourself with towels?

Answer: Towels and scarves can prevent direct contact of droplets onto your nose and mouth to a limited extent, but are not effective in protecting yourself against the new coronavirus. 

Question: Would wearing multiple masks improve its filtration effectiveness?

Answer: The key to effective filtration is the fit of the mask. Wearing multiple masks will affect its fit and obstruct your breathing. 

Question: Can we sanitise and reuse the masks if you want to extend its lifespan?

Answer: We cannot sanitise and reuse masks. If you want to extend its lifespan, cut a piece of gauze and line the inner part to prevent direct contact of the mask to your mouth and nose. 

Back to HKU Combats COVID-19