Refining the Covid-19 SOP for the public


A man wearing a mask improperly. While masks are key to stopping the spread of Covid-19, they are useless unless they cover both the nose and mouth. - Reuters

We are all in the long-haul stretch of the Covid-19 marathon, and we see fatigue and hopelessness setting in as repeated movement control orders and tighter restrictions are imposed.

We need to be science based with our daily SOP rather than resort to harsh measures. I would like to offer some evidence-based suggestions for key SOP that work, or do not work, for members of the public.

Our mantra for Covid-19 prevention should be three things: masks, ventilation and physical distancing. These are the key measures and all SOPs should be focused around them. All three relate to airborne transmission, which is the primary mechanism for Covid-19 spread.

Temperature scanning is of little value and should be stopped: By now, we are all accustomed to the temperature checks required at all premises.

However, some of us have been cautious about their value in detecting possible Covid-19 cases. Igor B. Mekjavic and Michael J. Tipton have written a detailed review of available data on the value of infrared thermographic screening for Covid-19 in the Journal of Experimental Physiology. The key points from all the studies reviewed suggest that:

> A measurement of skin (forehead) temperature does not provide an accurate assessment of core body temperature that is raised in a fever.

> Not all who have Covid-19 have a fever, especially in the early stages while still infectious. Hence a normal temperature check may provide false reassurance. We are aware that pre-symptomatic and currently asymptomatic individuals are important in Covid-19 transmissions.

> The reliability of infrared thermometers is an issue and they may vary by as much as 20°C. One study comparing the forehead temperature of 1,000 people with different infrared thermometers gave variable temperatures ranging from 31°C to 35.6°C. Another study showed a > 80% false negative (missed the fever) using infrared thermometers.

One of the authors of the review, Prof Tipton, said: “Using a surface temperature scanner to obtain a single surface temperature, usually of the forehead, is an unreliable method to detect the fever associated with Covid-19.”

Hence infrared thermometer screening is inaccurate and provides a false reassurance. In addition, we have seen locations where you have to get very close to the device, often touching it, to get a reading – this is high risk, of course. Queuing for a temperature check also slows movements and reduces physical distancing. It is best that we stop this SOP.

Make all sit-down food locations open air: Ventilation is key to reducing Covid-19 risk, especially in buildings. Here, we are focusing on F&B outlets.

While takeaway is a good option we also need to get back to sit-down dining to enable some to make a living (the government announced that dine-in is allowed from Feb 10, 2021, onwards, with two people per table). Lipinski and colleagues have reviewed the data on ventilation strategies to reduce the risk of disease transmission in high occupancy buildings. The data is clear that “recirculating ventilation” and systems that “move indoor air around” produce turbulent air flows with stale air and hence are of high risk.

What is preferred are “displacement ventilation systems” that remove contaminated indoor air and supply fresh air from outside constantly.

The US Centers for Disease Control and Prevention (CDC) have good guidance on improving ventilation in buildings and considerations for restaurants. The CDC suggests that restaurants prioritise outdoor dining with 2m spacing between tables. Small outdoor “bubbles” for dining are not safe as they restrict airflow. Any indoor dining should significantly restrict patrons, have 2m spacing between groups and have displacement ventilation, ie increase fresh outdoor air by opening windows and doors, and place fans at a window to exhaust room air to the outdoors and draw fresh air into the room (avoid placing fans in a way that could cause contaminated air to flow directly from one person over to another).

Hence all shops and restaurants should be open-air and non-airconditioned. We can make this happen by allowing tables and chairs to be put on the five-footway and perhaps even the road at night. Strictly limit indoor patrons, keep all doors and windows open and use fans judiciously as mentioned above.

The current single entry into a shop with tape to cordon off all other entries, may be harmful – we can still do mobile phone MySejahtera registration for entry at multiple sites.

Restaurant bathrooms remain a high risk location and should be avoided by patrons. Other useful tips include avoiding reusable menus or other items where surface spread may happen, enabling strict booking times and limited eating times to reduce crowding. Do not use straws for drinks as they pose a high contamination risk.

Some members of the public have expressed concern with the opening of pasar malam (night markets) but such open air markets are definitely a much safer place to eat at than a shopping complex or an enclosed airconditioned restaurant.

Improve mask quality and fit: Despite the widespread use of masks, we still have many issues with how they're used, especially poor usage. In addition, there is a growing call for the general public to replace cloth masks with medical/surgical masks.

There have been a number of good reviews looking at all the evidence for mask use: cloth mask effectiveness compared with medical/surgical masks, face shields, etc; they include work by Chu et al, Howard et al, Clapp et al, Edelstein & Ramakrishnan, and the Royal Society & the British Academy.

The key points from all the studies reviewed support that:

> Masks are effective in reducing transmission of infected Covid-19 respiratory particles to others (they protect others and protect us).

> When compliance with mask-wearing by the public is high, spread of the virus is effectively reduced.

> Cloth masks are effective if made with multiple layers and hybrid construction (following World Health Organisation guidelines for three layers: outer layer of non-absorbent material, such as polyester or polyester blend; middle layer of nonwoven non-absorbent material, such as polypropylene; inner layer of absorbent material, such as cotton). Cloth masks could provide 70%-90% filtration efficiency with a good fit and aluminium nose bridge.

> An improperly fitted mask can result in a significant decrease in filtration efficiency. This applies to both medical/surgical masks and cloth masks. Medical/surgical masks with ear loops are a poor fit (38% filtration efficiency) compared with those with ties (72% efficiency). Hence it is important that those wearing medical/surgical masks with ear loops work to improve the fit of those masks. (Note that the effective N95 respirator-type masks, used in hospitals, are not discussed here.)

Finally, no amount of mask usage is of value if the nose is exposed or the mask placed on the chin.

Open nature parks and jungle trails to the public: Outdoor activities are relatively safe (but not contact sports), provided unrelated persons maintain some physical distancing. Nature parks and jungle trails are safe locations for the public to go to. The current restrictions on forest reserves and jungle trails works against the public, who require some outlets for recreation.

Not all areas are covered in this brief write up but I hope the data and evidence quoted here supports improvements in our SOP and works towards improved control of the pandemic locally.

DATUK DR AMAR-SINGH HSS

Senior Consultant Paediatrician

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Covid-19 , SOPs , masks

   

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