1 Chapter 14a - COVID-19 - SARS-Cov-2 Chapter 14a - COVID-19 - SARS-CoV-2 26 April 2023 14a COVID-19 - SARS-CoV-2 NOTIFIABLE The disease COVID-19 is a disease of the respiratory tract caused by the SARS-CoV-2 virus, an RNA virus of the family of Coronaviridae and genus Betacoronavirus (Zhu et al, 2020). As with other coronaviruses, SARS-CoV-2 encodes four major structural proteins, spike (S), membrane (M), envelope (E) and a helical nucleocapsid (N) (Dhama et al, 2020) The S glycoprotein is considered the main antigenic target, including the receptor binding domain (RBD) which binds to angiotensin converting enzyme 2 (ACE2) on host cells (Kaur et al, 2020, Amanat et al, 2020). SARS-CoV-2 is primarily spread through respiratory droplets and aerosols and from direct person-to-person contact. The role of fomites appears to play a minor role in transmission. (Goldman et al. 2020). Viral RNA can persist in respiratory samples for 7-12 days after symptom onset, and viral loads are highest soon after symptom onset. Secondary attack rates within households are high (Lopez Bernal et al, 2020). The estimated reproductive number (R0) for the original wild-type strain was 2.8, with subsequent strains becoming more infectious. The Delta strain had an estimated R0 of 5.1 and the Omicron strain, which emerged in late 2021, had an estimated R0 of 9.5. (Liu et al. 2022) Common symptoms include headache, fatigue, cough, and muscle aches. In severe cases, COVID-19 can lead to pneumonia, acute respiratory distress syndrome, multiple organ failure and death. Compared to previous variants, Omicron is less likely to cause loss of sense of smell (anosmia) and more likely to cause a sore throat. (Menni et al. 2022, Pachetti et al, 2020). The long-term sequelae of COVID-19 infection, dubbed Long COVID or Post-Acute Sequelae of SARS-CoV-2 (PASC) infection, are an area of ongoing study. In the UK, 4.5% of cases report long-term symptoms 12-16 weeks after the initial infection. Reported symptoms are varied, involving most organ systems and affecting both physical and mental health. (Crook et al. 2022) Natural immunity due to previous infection lasts up to 1 year before beginning to wane, (Hall et al, 2022), although new strains and variants, such as Omicron, appear to exhibit greater immune escape, making reinfection more common.
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Related Documents
