A novel coronavirus emerged
in China in 2019 named as SARS-CoV-2, become a pandemic. Scientists,
Researchers and Health care professionals are still learning about it. It is an
endeavor to compile all the possible modes of transmission of the virus from
different reputed sources, so that it can help to understand the behavior of
the virus and suitably modify the preventive measures practiced at present.
This may change as more knowledge acquired on the virus.
- COVID-19 Outbreak Associated with Air Conditioning in Restaurant, Guangzhou, China, 2022:
During January 26–February 10, 2020, an outbreak of
2019 novel coronavirus disease in an air-conditioned restaurant in Guangzhou,
China, involved 3 family clusters. The airflow direction was consistent with droplet transmission. To prevent the
spread of the virus in restaurants, the researchers recommend increasing the
distance between tables and improving ventilation.
Reference 2. Aerosol
and Surface Distribution of Severe Acute Respiratory Syndrome Coronavirus 2 in
Hospital Wards, Wuhan, China, 2020
Contamination was greater in
intensive care units than general wards. Virus was widely distributed on
floors, computer mice, trash cans, and sickbed handrails and was detected in
air ≈4 m from patients.
In this study, researchers tested
surface and air samples from an intensive care unit (ICU) and a general
COVID-19 ward (GW) at Huoshenshan Hospital in Wuhan, China.
The study led to 3 conclusions.
First, SARS-CoV-2 was widely distributed in the air and on object surfaces in
both the ICU and GW, implying a potentially high infection risk for medical
staff and other close contacts. Second, the environmental contamination was
greater in the ICU than in the GW; thus, stricter protective measures should be
taken by medical staff working in the ICU. Third, the SARS-CoV-2 aerosol
distribution characteristics in the GW indicate that the transmission distance of
SARS-CoV-2 might be 4 m.
In
addition, their findings suggest that home isolation of persons with suspected
COVID-19 might not be a good control strategy. Family members usually do not
have personal protective equipment and lack professional training, which easily
leads to familial cluster infections. During the outbreak, the government of
China strove to the fullest extent possible to isolate all patients with
suspected COVID-19 by actions such as constructing mobile cabin hospitals in
Wuhan, which ensured that all patients
with suspected disease were cared for by professional medical staff and that
virus transmission was effectively cut off. As of the end of March, the
SARS-COV-2 epidemic in China had been well controlled.
Reference
3. Transmission
Potential of SARS-CoV-2 in Viral Shedding Observed at the
University of Nebraska Medical Center
University of Nebraska Medical Center
SARS-CoV-2 is
shed during respiration, toileting, and fomite contact, indicating
that infection may occur in both direct and indirect contact. Reference
that infection may occur in both direct and indirect contact. Reference
4.
The Role of Particle Size in Aerosolised
Pathogen Transmission:
In a review, particle sizes generated from
breathing, coughing, sneezing and talking showed healthy individuals generate
particles between 0.01 and 500 μm, and individuals with infections produce
particles between 0.05 and 500 μm. This indicates that expelled particles
carrying pathogens do not exclusively disperse by airborne or droplet
transmission, but avail of both methods simultaneously and current
dichotomous infection control precautions should be updated to include measures
to contain both modes of aerosolised transmission.
Reference
5.
Respiratory Virus RNA is Detectable
in Airborne and Droplet Particles
In a study, on breathing, 58% of participants
produced large particles (>5 µm) containing viral RNA and 80% produced small
particles (≤5 µm) carrying viral RNA. On coughing, 57% of participants produced
large particles containing viral RNA and 82% produced small particles
containing viral RNA. Forty five percent of participants produced samples
positive for hRV viral RNA and 26% of participants produced samples positive
for viral RNA from parainfluenza viruses.
Reference
6.
Potential for Airborne Transmission
of Infection in the Waiting Areas of Healthcare Premises: Stochastic Analysis
Using a Monte Carlo Model:
The researchers have found that under normal
circumstances the risk of acquiring a TB infection during a visit to a hospital
waiting area is minimal. Likewise, the risks associated with the transmission
of influenza, although an order of magnitude greater than those for TB, are
relatively small. By comparison, the risks associated with measles are high.
While the installation of air disinfection may be beneficial, when
seeking to prevent the transmission of airborne viral infection, it is
important to first minimize waiting times and the number of
susceptible individuals present, before turning to expensive
technological solutions. Reference
7. 7. COVID-19 Can Travel on
Shoes:
The floor swabs
also had a high rate of positive tests, potentially due to virus droplets
falling on the ground. Half of the ICU staff’s shoes also tested positive. As medical staff
walk around the ward, the virus can be tracked all over the floor, as indicated by the 100%
rate of positivity from the floor in the pharmacy, where there were no patients.
falling on the ground. Half of the ICU staff’s shoes also tested positive. As medical staff
walk around the ward, the virus can be tracked all over the floor, as indicated by the 100%
rate of positivity from the floor in the pharmacy, where there were no patients.
COVID-19 is
thought to spread mainly through close contact from person-to-person in
respiratory droplets from someone who is infected. People who are infected often have
symptoms of illness. Some people without symptoms may be able to spread virus.
Spread from contact with contaminated surfaces or objects. This virus is spreading
more efficiently than influenza, but not as efficiently as measles, which is highly contagious. Reference
9. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1
respiratory droplets from someone who is infected. People who are infected often have
symptoms of illness. Some people without symptoms may be able to spread virus.
Spread from contact with contaminated surfaces or objects. This virus is spreading
more efficiently than influenza, but not as efficiently as measles, which is highly contagious. Reference
9. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1
Aerosol and fomite
transmission of SARS-CoV-2 are plausible, since the virus can remain viable and
infectious in aerosols for hours and on surfaces up to days (depending on the inoculums
shed.
SARS-CoV-2
remained viable in aerosols for 3 hours in experimental conditions, with a
reduction in infectious titer from 103.5 to 102.7 TCID50
per liter of air.
SARS-CoV-2 was
more stable on plastic, viable virus was detected up to 72 hours
after application to this surface, although the virus titer was greatly reduced
(from 103.7 to 100.6 TCID50 per milliliter of medium
after 72 hours.
SARS-CoV-2 was
stable on stainless steel, although the virus titer was greatly
reduced from 103.7 to 100.6 TCID50 per
milliliter after 48 hours.
On copper, no viable SARS-CoV-2 was measured after 4
hours.
On cardboard, no viable SARS-CoV-2 was measured after 24
hours
Reference Reference
10. Modes of transmission of virus causing COVID-19: implications for IPC precaution recommendations; WHO
10. Modes of transmission of virus causing COVID-19: implications for IPC precaution recommendations; WHO
Respiratory
infections can be transmitted through droplets of different sizes: when the
droplet particles are > 5-10 μm in diameter they are referred to as respiratory
droplets, and when they are < 5μm in diameter, they are referred to
as droplet
nuclei. According to current evidence, COVID-19 virus is
primarily transmitted between people through respiratory droplets and contact
routes. In an analysis of 75,465 COVID-19 cases in China, airborne
transmission was not reported.
Reference
11. Speed of a Sneeze.
11. Speed of a Sneeze.
The largest droplets rapidly settle within 1 to
2 m away from the person. The smaller and evaporating droplets are trapped
in the turbulent puff cloud, remain suspended, and, over the course of seconds
to a few minutes, can travel the dimensions of a room and land up to 6 to
8 m away. Reference
12. Coughing and Aerosols
A maximum
airspeed of 8 m per second (18 mph) has been observed by researchers,
averaged during the half-second cough. The cough plume may project infectious
aerosols into the surrounding air.
It was
calculated that the original diameters of the respiratory drop lets ranged
from1to 2000 micron that 95% were between 2 and 100 micron and that the most
common were between 4 and 8 micron.
Reference
14. Seasonality of Respiratory Viral Infections
14. Seasonality of Respiratory Viral Infections
There can be
possible seasonal determinants in the epidemics of respiratory viruses as well
as host factors affected by these contributing factors. These include seasonal
changes in temperature, absolute humidity (AH), sunlight, vitamin status, and
host behavior. Animal transmission studies with guinea pigs and ferrets
have revealed that high RH (>60%) and low RH (<40%) seems to allow
viability of influenza viruses in droplets, while in intermediate RH (40% to 60%)
viruses become inactivated.
Since, the type
II alveolar cells, where the angiotensin-converting enzyme II concentrated, are
located deep in the respiratory tract, are not reachable by respiratory
droplets with a diameter of more than 5 micrometers, it appears likely that at
least, the severe cases of COVID-19 with viral pneumonia, are the result of air
borne transmission events.
The combination
of low humidity, temperature, and sunlight may trigger an impairment of the
local and systemic antiviral defense mechanisms, leading to the increased host
susceptibility to the respiratory viruses in winter.
In addition to
vaccines and antiviral drugs, non-pharmaceutical interventions to prevent
respiratory infections are gaining attention. Lifestyle (eating healthy,
sleeping more than 7 h/day) and hygiene practices (washing hands, wearing
facemasks) are known to increase antimicrobial resistance and prevent
transmission, respectively. In addition to these measures, we might consider
controlling the indoor environment to combat respiratory infections. Such
interventions with humidifiers (RH~45) have been realized since the 1960s with promising
results. Reference
15. Possible
Preventive Measures1:
- The first and foremost message emerging out of the researches is Social Distancing:
(i)
2
meters (6 feet), instead of 1 meter, wherever possible, like market places,
malls, hospital waiting areas, restaurants, and offices etc..
(ii)
Quick
disposal of patients and customers in commercial establishments (Malls &
Restaurants)
(iii)
At
least, 1 meter (3 Feet) distance in Triage facility in Hospital and during home
quarantine (If, no separate room is available).
(iv)
Barrier
(Glass) communication at Reception Counters in Acute Respiratory Infection or
Fever Clinic
(v)
Restriction
of entry of non-essential health care staff to the ICU/Rooms of COVID-19
patients, multi-tasking.
(vi)
Sanitization
of footwear, like two coir mat system2;
standing for 1 minute on a mat soaked with 1% Sodium Hypochlorite solution,
then drying foot on 2nd coir mat.
(vii)
As
health care persons (as well as some other professions, like saloon staff), who
cannot maintain distancing, Correct use of PPEs (separate donning &
doffing) as recommended for ICU and other places.
(viii)
Healthcare
supervised quarantine, in lieu of home quarantine.
2. Use of Facemasks: At least, Home-made mask for all, while going out (only to collect essential items). Standard PPEs for Hospital staff as per protocol.
2. Use of Facemasks: At least, Home-made mask for all, while going out (only to collect essential items). Standard PPEs for Hospital staff as per protocol.
3. Use
of HEPA (High Efficiency particulate Air Filter) filters in Hospital settings
(Acute Respiratory Infection treatment ICU/WARDS).
4. Following Good Hand Hygiene practice (Minimum 30 second, instead of 20 seconds) & Cough Etiquette.
5. Correct way of hand Sanitization (20 seconds, six steps as hand washing.
6. Maintaining healthy Lifestyle (eating healthy, sleeping more than 7 h/day), physical exercise (at least in Indoor), taking fresh fruits, and Vitamin D (Exposure to Sun is better).
7. Humidifier in Rooms to maintain RH (Relative Humidity = ~45).
8. Providing correct PPEs to patient.
9. Box-Shield Protected (as shown in NEJM video) Endotracheal Intubation/Ex-tubation/Splash generation procure.
10. Sanitization of frequently touched places, Bed-rail of patient, Door-knobs, Computer Key-board & Mouse, Lifts, stair-case rail, Hospital trolleys/stretchers/wheel-chairs, and handles of trolley/cart in Malls etc.. Sanitization of card boards (files, not required, if, not exposed; however, UV sterilizer can be used or exposed to Sun).
11. Cupper coating of steel surfaces in Hospital Settings (Like, bed-rails, bathroom door-knobs, and wheel-chairs etc.).
12. Covering the wheel-chair and stretchers with rubber mackintosh sheets that can be sanitized later.
13. Designing AIR-Conditioners with HEPA filters for hospital use, like used in Airplanes.
14. Managing laundry according to SoP (Soaking in detergent & hot water-washing/Use Hypochlorite) with correct use of PPEs.
15. Vaccination (When available).
4. Following Good Hand Hygiene practice (Minimum 30 second, instead of 20 seconds) & Cough Etiquette.
5. Correct way of hand Sanitization (20 seconds, six steps as hand washing.
6. Maintaining healthy Lifestyle (eating healthy, sleeping more than 7 h/day), physical exercise (at least in Indoor), taking fresh fruits, and Vitamin D (Exposure to Sun is better).
7. Humidifier in Rooms to maintain RH (Relative Humidity = ~45).
8. Providing correct PPEs to patient.
9. Box-Shield Protected (as shown in NEJM video) Endotracheal Intubation/Ex-tubation/Splash generation procure.
10. Sanitization of frequently touched places, Bed-rail of patient, Door-knobs, Computer Key-board & Mouse, Lifts, stair-case rail, Hospital trolleys/stretchers/wheel-chairs, and handles of trolley/cart in Malls etc.. Sanitization of card boards (files, not required, if, not exposed; however, UV sterilizer can be used or exposed to Sun).
11. Cupper coating of steel surfaces in Hospital Settings (Like, bed-rails, bathroom door-knobs, and wheel-chairs etc.).
12. Covering the wheel-chair and stretchers with rubber mackintosh sheets that can be sanitized later.
13. Designing AIR-Conditioners with HEPA filters for hospital use, like used in Airplanes.
14. Managing laundry according to SoP (Soaking in detergent & hot water-washing/Use Hypochlorite) with correct use of PPEs.
15. Vaccination (When available).
(A
Paradip Port Trust Hospital document)
Credits:
Acknowledgements
Sri Rinkesh Roy, IRTS, Chairman, Paradip Port Trust for reviewing of the article
Dr Raja Ravi Varma, Chief Medical Officer, Chennai Port Trust for use of hypochloride soaked mat
