Mrigank Warrier
While surface disinfection and thermal screening are the most widely used measures adopted by facilities to maintain a safe indoor environment and screen visitors before entry respectively, are they enough to offer a strong defense against Covid? New research reveals their relative efficacy and impact.
On the morning of the day I was to submit the piece — just hours before we went to press — a small news article caught my eye. Researchers in Hyderabad’s Centre for Cellular and Molecular Biology (CCMB) and Chandigarh’s Institute of Microbial Technology (IMT) revealed the results of a study conducted in three hospitals in each city, to find if the novel coronavirus was present in the air. They found the virus was circulating in the Covid-19 wards, while wards treating non-Covid-19 patients did not contain any traces of the virus. If I were to try and draw a parallel to non-medical facilities, I would find that they correlated to neither ward; neither are all the facility’s users known to be Covid-positive, nor are we certain that they are all Covid-negative. The public at large falls into the grey zone, and we must assume at least some of those now patronising theatres, malls, restaurants and offices are unknowingly Covid-positive.
The study also found that the chances of picking up the virus in air were directly related to the number of Covid-19 positive individuals in the room, symptomatic status and duration of exposure. Tamil Nadu has just allowed 100% occupancy in movie theatres, no non-office facilities are asking visitors if they have any symptoms; offices and theatres both have individuals spending a significant amount of time together.
Finally, research revealed that when Covid-positive individuals spent longer hours in a room, the virus was found in the air for more than two hours even farther than two metres from their seating places. For asymptomatic cases, the virus did not spread farther from them when they were seated in a room without air flow due to a fan or air-conditioner. Spending hours in a room is the definition of an office, and AC’s are ubiquitous in most modern facilities. Elsewhere in this issue, we have focussed on the importance of indoor quality, ventilation and HVAC systems. Let me instead quote the director of CCMB, and let us take note of what he has not
mentioned: “If we ensure that we follow hygiene protocols such as regular handwashing, using masks and preventing symptomatic people from public mixing, we can start getting back to normalcy”. Even an expert in microbiology has said nothing about surface disinfection and temperature screening, the two pillars of caution upon which most facilities have relied to reopen.
Are we focusing too much only on surface disinfection?
The early months of the pandemic were marked by panic, paranoia and an earnest need to protect human health above all else. The coronavirus — as is apparent in its official name — is novel, or new, and scientists had very little knowledge about how it does and doesn’t spread, and how exactly it can be contained. Consequently, facility managers scouted for the little authentic information that was available, which — in March and April — said that the virus can survive on various surfaces for varying lengths of time. While FM professionals could not (and still can’t) test every visitor, they could — and did — use chemicals which can eliminate the virus from surfaces. That the virus can survive on surfaces is still true. But now that the heat and dust of the initial storm has begun to settle down, and we have learnt to live with the virus, let us look at an article on this subject, published in Lancet — the world’s most prestigious medical journal. It found that most experiments which tested surfaces for survival of the virus required the introduction of an abnormally large titre of infectious viral particles on the surfaces to be tested, running into multiples of a million and tens of millions. I quote: “None of these studies present scenarios akin to real-life situations.”
In real life, few surfaces have been found naturally contaminated with enough viral particles to create a tangible risk for surface-to-human transmission. I further quote: “ In a study in which the authors tried to mimic actual conditions in which a surface might be contaminated by a patient, no viable SARS-CoV was detected on surfaces”. It is not at all my intention to suggest that FM providers should stop surface disinfection, or even reduce its frequency. After all, the same article still says, “The chance of transmission through inanimate surfaces is very small, and only in instances where an infected person coughs or sneezes on the surface, and someone else touches that surface soon after the cough or sneeze (within 1–2 hours).” Surface disinfection — particularly of high-touch surfaces — must certainly continue. My point is that it can no longer be considered the cornerstone of Covid protection measures.
How effective is temperature screening?
The sight of a security personnel standing outside the entrance to a facility, scanning visitors with a thermal gun — often without even noticing the reading or noting it down — has become commonplace. Yes, fever is one of the symptoms of Covid, but that does not make this type of screening a particularly reliable way to detect Covid-carrying individuals. Here’s why:
- Fever is not present in every patient with Covid-19, and by definition, is not present in an asymptomatic individual, who is still carrying around the virus.
- Fever is transient and follows a pattern throughout the day; a one-time spotcheck of temperature is a poor means of monitoring fever.
- Screening for fever is not sensitive enough to detect the vast majority of COVID-19 cases in the age group between 18 and 25 years, which is the age group that is most likely to be out and about.
- Medicines like paracetamol can mask fever, and cause normal readings on the device.
- Different facilities are following different cutoff points for what is considered an elevated temperature.
- Device readings are frequently inaccurate and may miss some low-grade temperatures. Thermal guns are less sensitive than oral thermometers, which obviously cannot be used for screening.
- Numerous reports have shown that temperature screening rarely identifies elevated temperatures. Let us assume a facility scans around 1,000 visitors a day. At any point in the pandemic, how many of them showed elevated levels? Considering government data on how many individuals have already been infected, how do these numbers correlate with the actual case load?
- Measurements are frequently inaccurate due to inaccurate positioning of the thermal gun relative to the examinee. An airport employee pointed the device at my shirt-covered shoulder before waving me through.
- Finally, fever is non-specific for Covid-19. Elevated temperatures captured by screening could be due to hundreds of other illnesses.
Mass temperature checks may create a false sense of security, and we cannot afford to compromise on vigilance. Dr Anthony Fauci – the world’s leading expert on Covid-19 has described temperature checks as “notoriously inaccurate”.
The bottom line
So, do we wash our hands (no pun intended) off surface disinfection and thermal screening? Not all all. I merely wish to emphasise what science has shown — that these two measures are merely parts of a much larger effort against Covid.
Anyone who lives in an urban area and has stepped out of home knows the utter lack of physical distancing being observed; FM professionals can impart soft skills training to their staff to persuade errant visitors to observe this at least whilst they are in the facility.
IMT director Sanjeev Khosla said: “Till the vaccines are available, the social vaccine i.e. wearing masks is the best prevention.” I can imagine how difficult it must be for FM staff to convince people who have been cooped up and masked for months to keep the mask on even when they’ve come out for some distractions and entertainment. But we must do what is hard, because the worst case scenario is unimaginable — another wave, another lockdown.
Let science direct our actions, not just our instincts.
