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The transmission of COVID-19 is the passing of coronavirus disease 2019 from person to person. COVID-19 is mainly transmitted when people breathe in air contaminated by droplets/aerosols and small airborne particles containing the virus. Infected people exhale those particles as they breathe, talk, cough, sneeze, or sing.
SARS-CoV-2, the causative agent of COVID-19, was first introduced to humans through zoonosis (transmission of a pathogen to a human from an animal), and a zoonotic spillover event is the origin of SARS-CoV-2 that is considered most plausible by the scientific community.
Some infectious diseases can be spread via respiratory droplets expelled from the mouth and nose, as when a person sneezes. A respiratory droplet is a small aqueous droplet produced by exhalation, consisting of saliva or mucus and other matter derived from respiratory tract surfaces. Respiratory droplets are produced naturally as a result of ...
The principal hypothesis for the origin of COVID-19 is that it became infectious to humans through a natural spillover event (zoonosis). That it became infectious to humans through escape from a laboratory where it was being studied is a minority position. The available evidence supports zoonosis.
Mild illnesses in humans include some cases of the common cold (which is also caused by other viruses, predominantly rhinoviruses), while more lethal varieties can cause SARS, MERS and COVID-19. In cows and pigs they cause diarrhea , while in mice they cause hepatitis and encephalomyelitis .
An infectious disease agent can be transmitted in two ways: as horizontal disease agent transmission from one individual to another in the same generation (peers in the same age group) [3] by either direct contact (licking, touching, biting), or indirect contact through air – cough or sneeze (vectors or fomites that allow the transmission of the agent causing the disease without physical ...
Dr. Watkins also reminds us that the best way to prevent respiratory infection is to get the flu, COVID-19, and RSV vaccines. “Don’t wait, the life you save can be your own.” “Don’t wait ...
The COVID‑19 vaccines are widely credited for their role in reducing the spread of COVID‑19 and reducing the severity and death caused by COVID‑19. [211] [217] According to a June 2022 study, COVID‑19 vaccines prevented an additional 14.4 to 19.8 million deaths in 185 countries and territories from 8 December 2020 to 8 December 2021. [218]