Epidemiology

The World Health Organization (WHO) was informed of cases of pneumonia of unknown microbial etiology associated with Wuhan City, Hubei Province, China on 31 December 2019. The WHO later announced that a novel coronavirus had been detected in samples taken from these patients. Since then, the epidemic escalated and rapidly spread around the world, with the WHO first declaring a public health emergency of international concern (PHEIC) on 30 January 2020, and then formally declaring it a pandemic on 11 March 2020. The WHO declared that COVID-19 no longer constitutes a PHEIC in May 2023.

Cases have been reported across all continents since the beginning of the pandemic, with over 776 million confirmed cases and over 7 million deaths reported globally.[17]

[Figure caption and citation for the preceding image starts]: Number of COVID-19 cases reported weekly by WHO Region, and global deaths, as of 15 September 2024World Health Organization [Citation ends].com.bmj.content.model.Caption@3959b16e

Updated case counts are available from the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC):

Older people ≥70 years of age and males are at increased risk for infection and severe disease.[18] Adolescents appear to have similar susceptibility to infection as adults, and children have a lower susceptibility. However, evidence is conflicting and the detailed relationship between age and susceptibility to infection requires further investigation.[19][20] Unlike adults, children do not seem to be at higher risk for severe disease based on age or sex.[21] Variants may spread more effectively and rapidly among young children compared with the wild-type virus, although hospitalization rates decreased.[22][23]

The incidence of infection in healthcare workers ranged from 0% to 49.6%, and the prevalence of seropositivity ranged from 1.6% to 31.6%. There was no association between age, sex, or healthcare worker role (i.e., nurse versus physician) and the risk for infection, based on moderate-certainty evidence. There was an association between Black race or Hispanic ethnicity and increased risk for infection compared with White race or non-Hispanic ethnicity, based on moderate-certainty evidence. There was an association between use of personal protective equipment and decreased risk for infection, based on moderate-certainty evidence.[24][25]

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