Over 516 million cases have been reported globally, with approximately 6.25 million deaths according to the World Health Organization. The US has the highest number of reported infections and deaths in the world. India, Brazil, France, and Germany have the highest number of infections after the US. Brazil, India, Russia, and Mexico have the highest number of deaths after the US.
Current detailed data for the US situation is available.
In China, 87% of confirmed cases were ages 30 to 79 years and 3% were ages 80 years or older in the first wave of the pandemic. Approximately 51% of patients were male.[23]Novel Coronavirus Pneumonia Emergency Response Epidemiology Team. The epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19) in China [in Chinese]. Zhonghua Liu Xing Bing Xue Za Zhi. 2020 Feb 17;41(2):145-51.
http://weekly.chinacdc.cn/en/article/id/e53946e2-c6c4-41e9-9a9b-fea8db1a8f51
http://www.ncbi.nlm.nih.gov/pubmed/32064853?tool=bestpractice.com
In the UK, the median age of patients was 73 years and males accounted for 60% of admissions in a prospective observational cohort study of more than 20,000 hospitalized patients in the first wave.[24]Docherty AB, Harrison EM, Green CA, et al. Features of 20 133 UK patients in hospital with covid-19 using the ISARIC WHO clinical characterisation protocol: prospective observational cohort study. BMJ. 2020 May 22;369:m1985.
https://www.bmj.com/content/369/bmj.m1985
http://www.ncbi.nlm.nih.gov/pubmed/32444460?tool=bestpractice.com
In the US, older patients (ages ≥65 years) accounted for 31% of all cases, 45% of hospitalizations, 53% of intensive care unit admissions, and 80% of deaths in the first wave, with the highest incidence of severe outcomes in patients ages ≥85 years.[25]CDC COVID-19 Response Team. Severe outcomes among patients with coronavirus disease 2019 (COVID-19): United States, February 12 - March 16, 2020. MMWR Morb Mortal Wkly Rep. 2020 Mar 27;69(12):343-6.
https://www.cdc.gov/mmwr/volumes/69/wr/mm6912e2.htm?s_cid=mm6912e2_w
http://www.ncbi.nlm.nih.gov/pubmed/32214079?tool=bestpractice.com
Adolescents appear to have similar susceptibility to infection as adults.[26]Viner RM, Mytton OT, Bonell C, et al. Susceptibility to SARS-CoV-2 infection among children and adolescents compared with adults: a systematic review and meta-analysis. JAMA Pediatr. 2021 Feb 1;175(2):143-56.
https://jamanetwork.com/journals/jamapediatrics/fullarticle/2771181
http://www.ncbi.nlm.nih.gov/pubmed/32975552?tool=bestpractice.com
However, evidence is conflicting and the detailed relationship between age and susceptibility to infection requires further investigation.[27]World Health Organization. COVID-19 disease in children and adolescents: scientific brief, 29 September 2021. 2021 [internet publication].
https://www.who.int/publications/i/item/WHO-2019-nCoV-Sci_Brief-Children_and_adolescents-2021.1
In the US, hospitalizations in adolescents peaked at 2.1 per 100,000 in early January 2021, declined to 0.6 per 100,000 in March, and rose to 1.3 per 100,000 in April. Among hospitalized adolescents, approximately one third required admission to the intensive care unit and 5% required mechanical ventilation. This data was based on 204 adolescents who were likely hospitalized primarily for COVID-19 during January 1 to March 31 2021.[28]Havers FP, Whitaker M, Self JL, et al. Hospitalization of adolescents aged 12-17 years with laboratory-confirmed COVID-19: COVID-NET, 14 states, March 1, 2020–April 24, 2021. MMWR Morb Mortal Wkly Rep. 2021 Jun 11;70(23):851-7.
https://www.cdc.gov/mmwr/volumes/70/wr/mm7023e1.htm?s_cid=mm7023e1_w
http://www.ncbi.nlm.nih.gov/pubmed/34111061?tool=bestpractice.com
Evidence suggests that children have a lower susceptibility to infection compared with adults.[26]Viner RM, Mytton OT, Bonell C, et al. Susceptibility to SARS-CoV-2 infection among children and adolescents compared with adults: a systematic review and meta-analysis. JAMA Pediatr. 2021 Feb 1;175(2):143-56.
https://jamanetwork.com/journals/jamapediatrics/fullarticle/2771181
http://www.ncbi.nlm.nih.gov/pubmed/32975552?tool=bestpractice.com
However, evidence is conflicting and the detailed relationship between age and susceptibility to infection requires further investigation.[27]World Health Organization. COVID-19 disease in children and adolescents: scientific brief, 29 September 2021. 2021 [internet publication].
https://www.who.int/publications/i/item/WHO-2019-nCoV-Sci_Brief-Children_and_adolescents-2021.1
Emerging data suggests variants may spread more effectively and rapidly among young children, although hospitalization rates decreased.[29]Somekh I, Stein M, Karakis I, et al. Characteristics of SARS-CoV-2 infections in Israeli children during the circulation of different SARS-CoV-2 variants. JAMA Netw Open. 2021 Sep 1;4(9):e2124343.
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2783851
http://www.ncbi.nlm.nih.gov/pubmed/34491353?tool=bestpractice.com
Most cases in children are from familial clusters, or children who have a history of close contact with an infected patient. It is rare for children to be the index case in household transmission clusters.[30]Zhu Y, Bloxham CJ, Hulme KD, et al. A meta-analysis on the role of children in severe acute respiratory syndrome coronavirus 2 in household transmission clusters. Clin Infect Dis. 2021 Jun 15;72(12):e1146-53.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7799195
http://www.ncbi.nlm.nih.gov/pubmed/33283240?tool=bestpractice.com
Unlike adults, children do not seem to be at higher risk for severe illness based on age or sex.[31]Castagnoli R, Votto M, Licari A, et al. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children and adolescents: a systematic review. JAMA Pediatr. 2020 Sep 1;174(9):882-9.
https://jamanetwork.com/journals/jamapediatrics/fullarticle/2765169
http://www.ncbi.nlm.nih.gov/pubmed/32320004?tool=bestpractice.com
In the UK, a prospective observational cohort study found that children and young adults represented 0.9% of all hospitalized patients at the time. The median age of children admitted to hospital was 4.6 years, 56% were male, 35% were under 12 months of age, and 42% had at least one comorbidity. In terms of ethnicity, 57% were White, 12% were South Asian, and 10% were Black. Age under 1 month, age 10 to 14 years, and Black race were risk factors for admission to critical care.[32]Swann OV, Holden KA, Turtle L, et al. Clinical characteristics of children and young people admitted to hospital with covid-19 in United Kingdom: prospective multicentre observational cohort study. BMJ. 2020 Aug 27;370:m3249.
https://www.bmj.com/content/370/bmj.m3249
http://www.ncbi.nlm.nih.gov/pubmed/32960186?tool=bestpractice.com
In the US, a retrospective cohort study of over 135,000 children found that the mean age of infected children was 8.8 years, and 53% were male. In terms of ethnicity, 59% were White, 15% were Black, 11% were Hispanic, and 3% were Asian. Only 4% of children tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in this population, and clinical manifestations were typically mild.[33]Bailey LC, Razzaghi H, Burrows EK, et al. Assessment of 135,794 pediatric patients tested for severe acute respiratory syndrome coronavirus 2 across the United States. JAMA Pediatr. 2021 Feb 1;175(2):176-84.
https://jamanetwork.com/journals/jamapediatrics/fullarticle/2773298
http://www.ncbi.nlm.nih.gov/pubmed/33226415?tool=bestpractice.com
Globally, the case fatality rate in children appears to be higher in low- and middle-income countries compared with high-income countries.[34]Kitano T, Kitano M, Krueger C, et al. The differential impact of pediatric COVID-19 between high-income countries and low- and middle-income countries: a systematic review of fatality and ICU admission in children worldwide. PLoS One. 2021 Jan 29;16(1):e0246326.
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0246326
http://www.ncbi.nlm.nih.gov/pubmed/33513204?tool=bestpractice.com
The overall prevalence in pregnant and recently pregnant women attending or admitted to hospital for any reason has been estimated to be 10%; however, the rate varies across studies and countries.[35]Allotey J, Stallings E, Bonet M, et al. Clinical manifestations, risk factors, and maternal and perinatal outcomes of coronavirus disease 2019 in pregnancy: living systematic review and meta-analysis. BMJ. 2020 Sep 1;370:m3320.
https://www.bmj.com/content/370/bmj.m3320
http://www.ncbi.nlm.nih.gov/pubmed/32873575?tool=bestpractice.com
[36]Allotey J, Stallings E, Bonet M, et al. Update to living systematic review on covid-19 in pregnancy. BMJ. 2021 Mar 10;372:n615.
https://www.bmj.com/content/372/bmj.n615
http://www.ncbi.nlm.nih.gov/pubmed/33692025?tool=bestpractice.com
A meta-analysis of over 2500 pregnant women with confirmed disease found that 73.9% of women were in the third trimester; 50.8% were from Black, Asian, or minority ethnic groups; 38.2% were obese; and 32.5% had chronic comorbidities.[37]Khalil A, Kalafat E, Benlioglu C, et al. SARS-CoV-2 infection in pregnancy: a systematic review and meta-analysis of clinical features and pregnancy outcomes. EClinicalMedicine. 2020 Aug;25:100446.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7334039
http://www.ncbi.nlm.nih.gov/pubmed/32838230?tool=bestpractice.com
In the UK, the estimated incidence of admission to hospital with confirmed infection in pregnancy is 4.9 per 1000 maternities. Most women were in the second or third trimester. Of these patients, 41% were ages 35 years or older, 56% were from Black or other ethnic minority groups, 69% were overweight or obese, and 34% had preexisting comorbidities.[38]Knight M, Bunch K, Vousden N, et al. Characteristics and outcomes of pregnant women admitted to hospital with confirmed SARS-CoV-2 infection in UK: national population based cohort study. BMJ. 2020 Jun 8;369:m2107.
https://www.bmj.com/content/369/bmj.m2107
http://www.ncbi.nlm.nih.gov/pubmed/32513659?tool=bestpractice.com
In the US, approximately 205,000 cases have been reported in pregnant women (as of 2 May 2022), with over 32,000 hospitalizations and 292 deaths.[39]Centers for Disease Control and Prevention. Data on COVID-19 during pregnancy: severity of maternal illness. 2022 [internet publication].
https://covid.cdc.gov/covid-data-tracker/?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fcoronavirus%2F2019-ncov%2Fcases-updates%2Fspecial-populations%2Fpregnancy-data-on-covid-19.html#pregnant-population
According to an analysis of approximately 400,000 women ages 15 to 44 years with symptomatic disease, Hispanic and non-Hispanic Black pregnant women appear to be disproportionately affected during pregnancy.[40]Zambrano LD, Ellington S, Strid P, et al. Update: characteristics of symptomatic women of reproductive age with laboratory-confirmed SARS-CoV-2 infection by pregnancy status: United States, January 22–October 3, 2020. MMWR Morb Mortal Wkly Rep. 2020 Nov 6;69(44):1641-7.
https://www.cdc.gov/mmwr/volumes/69/wr/mm6944e3.htm
http://www.ncbi.nlm.nih.gov/pubmed/33151921?tool=bestpractice.com
Approximately 14% of the cases reported to the World Health Organization are in healthcare workers (range 2% to 35%).[41]World Health Organization. Prevention, identification and management of health worker infection in the context of COVID-19. 2020 [internet publication].
https://www.who.int/publications/i/item/10665-336265
The incidence of infection in healthcare workers ranged from 0% to 49.6% (by polymerase chain reaction), and the prevalence of SARS-CoV-2 seropositivity ranged from 1.6% to 31.6%. The wide ranges are likely related to differences in settings, exposures, rates of community transmission, symptom status, use of infection control measures, and other factors. There was no consistent association between sex, age, or healthcare worker role (i.e., nurse versus physician) and risk for infection or seropositivity. However, non-White race (Black, Asian or Asian/Pacific Islander, or combined non-White races) or Hispanic ethnicity was significantly associated with an increased risk of infection compared with White people. Working in a hospital unit with COVID-19 patients, being a frontline worker, and direct or prolonged patient contact were also associated with an increased risk for infection. Household or private setting exposure was a stronger risk factor than work exposure in most studies. The presence of immunoglobulin G antibodies was associated with a decreased risk for reinfection.[42]Chou R, Dana T, Buckley DI, et al. Epidemiology of and risk factors for coronavirus infection in health care workers: a living rapid review. Ann Intern Med. 2020 Jul 21;173(2):120-36.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7240841
http://www.ncbi.nlm.nih.gov/pubmed/32369541?tool=bestpractice.com
[43]Chou R, Dana T, Buckley DI, et al. Update alert 10: epidemiology of and risk factors for coronavirus infection in health care workers. Ann Intern Med. 2021 Nov 16;M21-4294.
https://www.acpjournals.org/doi/10.7326/M21-4294
http://www.ncbi.nlm.nih.gov/pubmed/34781714?tool=bestpractice.com