How do we contract COVID-19 and how to prevent it?
A Documentary by Dr. Mohammad Sultan Khuroo
How do we contract COVID-19 and how to prevent it?
A Documentary by
Dr. Mohammad Sultan Khuroo
The coronavirus infection which originated from Wuhan, China in December 2019 has turned in to a global catastrophe. The virus has been designated as Severe Acute Respiratory Syndrome-Coronavirus-2 or SARS-CoV-2 and the disease caused by the agent as Coronavirus Disease 2019 or COVID-19.
The virus is highly optimized for human transmission and the infectivity of the pathogen is much higher than other respiratory viruses namely influenza virus and its other 2 sister human-coronaviruses namely SARS and MERS. As of today, in absence of a highly effective drug and an efficacious vaccine, mitigation and preventive measures are most important to fight the pandemic. In order to prevent transmission, one must know how does the virus spread from one person to another. The knowledge about modes of transmission of coronavirus is evolving and as of today, several pathways are being actively explored and their relative significance evaluated.
Droplet transmission is being recognized as the Dominant mode of transmission of the virus. Respiratory Droplets of 5-10 µm are generated at sneeze, cough, loud talk & singing and thrown in to the air. Such Droplets if generated from an infected person contain the virus. These droplets are heavy and can travel up to a maximum distance of 6 feet in the air and drop on the surfaces. If a susceptible host is within 6 feet distance to the index case, Virus enters and attaches to mouth, nose and eyes. Such a situation can occur anywhere when you confront the infected person. We have to remember that the infected person carrying the virus may be with or without symptoms. Actions needed to Block such transmission include: Both persons confronting each other must wear face masks and keep a distance of 6 ft from each other. Practice of handwashing shall add further protection to you from infection.
Ultimately, wearing masks and social distancing are powerful tools to cut all the hypothesized routes of transmission.
There is evolving evidence that airborne (aerosol) transmission of disease may play a role in spread of COVID-19. Aerosol are small Respiratory droplets of < 5 µm which are generated at heavy breathing, talking & singing. Aerosol remain and float in air. The aerosol from an infected person contain the virus particles for varying period up to 3 hours.
Aerosols in the air behave differently based on location where they are generated: -
In an Open airy environment with sparse public presence, like a Golf course, a meadow, a wide roadside, an outside airy restaurant etc, aerosol disperse and sway with air currents and pose little risk to the susceptible persons. However, such places could pose a risk of disease spread if they are crowded like beaches, playgrounds, open marriage halls etc. The disease spread can occur due to droplet infection. So, it is mandatory to practice of wearing a mask, keep social distancing and hand washing to prevent contracting the virus.
In a closed environment with little aeration and crowds like choir parties, movie theatres, religious places, indoor restaurants, gyms, amusement parks, social gatherings and political party functions, Aerosol containing virus builds up in closed spaces and is inhaled by those susceptible to infection and enters lungs directly. It may enter the airways even if you are wearing a facemask (around the edges). The exact significance of this mode of transmission of virus is under serious scientific debate and has been documented in several situations namely Choir parties. So, during pandemics, it is advisable to Avoid crowded places, close-contact settings and confined and enclosed spaces with poor ventilation and Ensure good ventilation in indoor settings, including homes and offices. It is believed that People are more likely to contract the new coronavirus from members of their own households than from contacts outside the home.
Aerosol can be generated in healthcare places namely theatres, endoscopy & bronchoscopy procedure rooms, ENT & dental clinics etc. Here Significant aerosol circulating is generated and circulated in air and can be inhaled and enter lungs directly. It is mediatory that higher levels of personal protective equipment be worn by the healthcare workers to protect themselves.
Another way coronavirus can possibly spread is through fomites. Fomites are desktop surfaces, doorknobs, door handles, drinking cups, computer keyboards, pens, boxes, currency notes, stethoscope, and other medical appliances, etc. Droplets generated and coughed by infected persons containing the virus drop on such objects. Virus stays alive for varying periods depending upon the material, being more stable on plastics and stainless steel than on cardboard. On touching such objects, one can carry the virus through hands to the mouth, nose and eyes.; Intensity of transmission through fomites is definite but supposed to be low and has been overemphasized. In order to protect from contracting infection through fomites, one needs to Avoid touching mouth, nose & eyes; Disinfect surfaces regularly; handle all incoming items with care following infection control measures; handwashing practice after you touch a fomite.
Another mode of transmission under scrutiny is Enteric transmission. Virus is excreted in feces and urine. As of today, there is no evidance that fecal-oral spread of the virus occurs through direct contact, water and food items. However, it is Worthwhile to follow infection control measures like Handwashing after using washrooms and prior to taking any food.
Flushing of toilets produces ‘toilet plumes’ and significant aerosol in the closed environment of toilets especially in COVID-19 healthcare units; next person entering toilet can inhale the aerosol with virus and get infected; Data about this mode of spread are not available. So, it is imperative that we Cover the toilet with a lid prior to flushing; If not possible avoid flushing and use a bucket of water to clean the toilet. Intensive infection control practices in washrooms of COVID-19 units is mandatory.
COVID in pregnant mothers is a matter of concern and is being often reported. This raises the possibility of vertical or perinatal transmission of the virus to the fetus or the new-born. As of today, there is no evidence in the literature about such a transmission except an isolated event recently reported. It is our duty to do Intensive testing of neonates for infection. Of course, babies need to be isolated till mother turns non-infectious.
As of today, there is no evidence that Food can spread coronavirus. Knowledge about this form of transmission is evolving.
The fact that so many seemingly innocuous activities can transmit the virus can be scary. And it can be even scarier not knowing the actual risks associated with each transmission route — without that information, how can we take the right steps to protect ourselves? But ultimately there is some reassurance in the data as well (Tia Ghose Live Science April 7, 2020).