How is COVID-19 transmitted?

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Understanding COVID-19 Transmission

Human-to-Human Transmission via Respiratory Droplets

COVID-19, caused by the SARS-CoV-2 virus, is primarily transmitted from person to person through respiratory droplets. These droplets are expelled when an infected person coughs, sneezes, or talks, and can be inhaled by individuals in close proximity, leading to infection . This mode of transmission is well-documented and is considered the dominant route for the spread of the virus.

Aerosol Transmission in Indoor Environments

Aerosol transmission, where smaller virus-laden particles remain suspended in the air and can be inhaled, is another significant route of COVID-19 spread, especially in indoor settings. Studies have shown that aerosols can effectively transmit the virus in environments such as offices, classrooms, and social gatherings, particularly when ventilation is poor . This mode of transmission underscores the importance of wearing masks and ensuring proper ventilation to reduce infection risk.

Direct Contact and Surface Transmission

Direct contact with infected individuals or contaminated surfaces can also lead to COVID-19 transmission. The virus can survive on surfaces for varying periods, and touching these surfaces followed by touching the face, especially the mouth, nose, or eyes, can result in infection . Regular hand hygiene and disinfection of surfaces are critical preventive measures.

Potential Transmission via Ocular Surfaces

There is some evidence suggesting that the virus may enter the body through the eyes. Although the presence of the virus in conjunctival swabs is not consistently observed, the possibility of transmission through the ocular surface, particularly via the nasolacrimal ducts, cannot be entirely ruled out. Healthcare workers are advised to use eye protection to mitigate this risk.

Vertical Transmission from Mother to Infant

The likelihood of vertical transmission, where the virus is passed from a pregnant mother to her baby, appears to be low. Studies indicate that only a small percentage of infants born to COVID-19 positive mothers test positive for the virus at birth. However, antibodies against SARS-CoV-2 have been detected in some infants, suggesting some level of natural passive immunity.

Conclusion

COVID-19 is primarily transmitted through respiratory droplets and aerosols, with direct contact and surface transmission also playing roles. While the potential for ocular and vertical transmission exists, these routes are less common. Preventive measures such as mask-wearing, hand hygiene, surface disinfection, and proper ventilation are essential to curb the spread of the virus. Understanding these transmission mechanisms is crucial for developing effective public health strategies and protecting vulnerable populations.