Acute respiratory tract infections (ARIs) are among the most prevalent infections in childhood worldwide, with the highest incidence among children younger than 2 years.^1,2 Risk factors for these infections include being male, living in crowded conditions, and being exposed to child care centers and passive smoking.^1,3 However, these factors explain only a fraction of the variation in incidence between children. Mannose-binding lectin (MBL) is a serum protein believed to play an important role in the innate immune response.⁴ A single gene, MBL2, located at chromosome 10, codes for human MBL.^5,6 Mannose-binding lectin may exert its action through binding to high mannose and N-acetylglucosamine oligosaccharides present on a variety of microorganisms, thereby activating the complement system by MBL-associated serine proteases and interacting with novel receptors on phagocytes.^7-9 As part of the innate immune system, the protein is considered particularly important in the vulnerable period of infancy before adequate specific immune protection is established by the adaptive immune system.¹⁰

The Paleo-Eskimo Saqqaq and Independence I cultures, documented from archaeological remains in Northern Canada and Greenland, represent the earliest human expansion into the New World's northern extremes. However, their origin and genetic relationship to later cultures are unknown. We sequenced a mitochondrial genome from a Paleo-Eskimo human by using 3400-to 4500-year-old frozen hair excavated from an early Greenlandic Saqqaq settlement. The sample is distinct from modern Native Americans and Neo-Eskimos, falling within haplogroup D2a1, a group previously observed among modern Aleuts and Siberian Sireniki Yuit. This result suggests that the earliest migrants into the New World's northern extremes derived from populations in the Bering Sea area and were not directly related to Native Americans or the later Neo-Eskimos that replaced them.

Objective. To describe incidence and temporal trends of intussusceptions in Danish children during 1980 to 2001. Methods. A population-based cohort study was conducted of 1.67 million children who were younger than 5 years during 1980 to 2001 and were followed up for 6.66 million person-years. The Danish National Patient Registry was used to identify cases of intussusception in the cohort. Age-specific incidence rates were main outcome measure. Results. A total of 1814 cases of intussusception among children who were younger than 5 years were reported from 1980 to 2001. The incidence rate remained fairly constant during 1980 to 1990 but decreased by 55% (95% confidence interval: 43%–65%) from 1990 to 2001. The reduction was most pronounced among children aged 3 to 5 months. Conclusions. The incidence of intussusception among Danish children declined significantly during the 1990s, particularly among infants 3 to 5 months of age.

A considerable number of individuals infected with SARS-CoV-2 continue to experience symptoms after the acute phase. Here, we report findings from a nationwide questionnaire study in Denmark including 61,002 RT-PCR confirmed SARS-CoV-2 cases and 91,878 test-negative controls aged 15-years or older. Six to twelve months after the test, the risks of 18 out of 21 symptoms were elevated among test-positives. The largest adjusted risk differences (RD) were observed for dysosmia (RD = 10.92%, 95% CI 10.68–11.21%), dysgeusia (RD = 8.68%, 95% CI 8.43–8.93%), fatigue/exhaustion (RD = 8.43%, 95%CI 8.14–8.74%), dyspnea (RD = 4.87%, 95% CI 4.65–5.09%) and reduced strength in arms/legs (RD = 4.68%, 95% CI 4.45–4.89%). During the period from the test and until completion of the questionnaire, new diagnoses of anxiety (RD = 1.15%, 95% CI 0.95–1.34%) or depression (RD = 1.00%, 95% CI 0.81–1.19%) were also more common among test-positives. Even in a population where the majority of test-positives were not hospitalized, a considerable proportion experiences symptoms up to 12 months after infection. Being female or middle-aged increases risks.

Acute respiratory infections cause considerable morbidity among Inuit children, but there is very little information on the risk factors for these infections in this population. To identify such factors, the authors performed a prospective community-based study of acute respiratory infections in an open cohort of 288 children aged 0–2 years in the town of Sisimiut, Greenland. Between July 1996 and August 1998, children were monitored weekly, and episodes of upper and lower respiratory tract infections were registered. Risk factor analyses were carried out using a multivariate Poisson regression model adjusted for age. Risk factors for upper respiratory tract infections included attending a child-care center (relative risk = 1.7 compared with home care) and sharing a bedroom with adults (relative risk = 2.5 for one adult and 3.1 for two adults). Risk factors for lower respiratory tract infections included being a boy (relative risk = 1.5), attending a child-care center (relative risk = 3.3), exposure to passive smoking (relative risk = 2.1), and sharing a bedroom with children aged 0–5 years (relative risk = 2.0 for two other children). Breastfeeding tended to be protective for lower respiratory tract infections. The population-attributable risk of lower respiratory tract infections associated with passive smoking and child-care centers was 47% and 48%, respectively. The incidence of acute respiratory infections among Inuit children may be reduced substantially through public health measures.