For quite some time now, we've maintained that SARS-CoV-2, the virus responsible for COVID-19, can linger on surfaces. Even when the CDC seemed to suggest otherwise, we continued to emphasize this fact. Additionally, we've discussed how the number of asymptomatic cases might be underreported. By now, it feels like we're speaking to an audience that already agrees with us.
However, today, a new study has been released in *mSphere*, focusing on something that hasn't received much attention: precisely *how* do COVID-19 patients spread the virus to their surroundings? And where does it end up?
The study reveals that both symptomatic and asymptomatic COVID-19 patients can contaminate their environment. This makes logical sense—of course, it's not just critically ill patients in hospitals who can transmit the virus. The study also mentions a "false sense of security," which resonates as we see case maps turning red again despite bars and restaurants reopening.
Here’s what you should know:
- Surfaces pose a significant risk! PCR tests found that 39.3% of surface samples were positive for SARS-CoV-2. In some hospital rooms, over 90% of surfaces tested positive for live virus.
- Air samples came back negative! You can breathe easy in an unoccupied room, provided you avoid touching anything. Masks remain crucial.
- The study suggests that self-isolation at home might not work well for asymptomatic patients. Alternative solutions like shelter hospitals, similar to those in China, could be more effective.
Let’s talk about how this study was conducted. Researchers in Chengdu, China, collected samples from the hospital rooms of 13 COVID-19 patients. Eleven of these patients were symptomatic, but two were asymptomatic despite testing positive. These individuals had returned from abroad and were placed in isolation after testing positive. Their rooms were under negative pressure, ensuring air circulated inside without escaping.
On April 2, researchers sampled the air and various objects in these rooms, including bedrails, door handles, light switches, flush buttons, sink rims, bowls, bedside tables, bedsheets, pillows, walls, floors, and air exhaust outlets. Despite thorough cleaning twice daily with a 2,000 mg/L chlorine solution, the objects were heavily contaminated. Out of 112 surface samples, 44 tested positive for SARS-CoV-2, representing 39.3% of all objects.
In some rooms, only 4.6% of objects were positive, whereas in others, 95.7% tested positive. The most contaminated areas included bedrails (53.9%), pillows (50%), bedsheets (50%), air exhaust outlets (50%), and light switches (40%).
Nurses diligently disinfected the rooms and toilets twice daily. Samples were taken 4-7 hours after the first cleaning session. One room with an asymptomatic patient had four positive sites: bedrails, pillows, bed sheets, and the air exhaust outlet. This underscores that asymptomatic patients can still contaminate their surroundings, exposing those who come into contact with them, such as family members and healthcare workers.
The study also noted that aerosols were less prevalent compared to droplets. While the virus is primarily transmitted person-to-person, all air samples in this study were negative for SARS-CoV-2. Samples were taken during routine morning activities from 0.6 meters away from the patient for 15 minutes. Despite this, half of the air exhaust outlets tested positive. Rooms with positive outlets had more contaminated surfaces, suggesting small virus particles could travel through the air and settle on surfaces.
Even though the study found fewer aerosolized particles, it highlighted that droplets spread the virus through the air and onto surfaces. Virus particles could still drift through the air and land on surfaces. Talking to someone could still result in exhaled particles making you sick. Therefore, wearing a mask remains critical.
The researchers noted a significant limitation: while they collected 1,500 liters of air per sample, this volume is minimal compared to the entire room. They tested for viral nucleic acid but didn’t culture the virus to check its viability. Thus, further research is needed to fully understand how the virus behaves in the air.
This study was conducted in a hospital setting. We still don’t know how particles move in homes, stores, or outdoors. This doesn’t change the advice to wear masks around others who could sneeze, cough, or laugh near you. However, after someone leaves a room, catching the virus from the air you breathe is unlikely. Instead, focus on cleaning surfaces you touch.
The worst scenario is in households where social distancing has relaxed or cleaning has been neglected. An asymptomatic or presymptomatic family member could contaminate every surface before anyone knows they have COVID-19. Cleaning alone might not prevent the virus from spreading through the air conditioning or onto surfaces.
Stay home as much as possible, clean frequently, wear masks in public, and sanitize regularly.
Additional mask tips:
- Smooth Operator: A Gentleman's Guide to Beards, Masks, and Pandemic Shaving
- DIY N95 Masks: Repurpose an Old Prom Dress
- Review: The GORUCK Face Mask
- How to Safely Put On and Remove Personal Protective Equipment
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