Study: 0 of 107 French teens with MIS-C fully vaccinated against COVID-19
A study of 107 French teens hospitalized with the COVID-19–related multisystem inflammatory syndrome in children (MIS-C) shows that none had been fully vaccinated against SARS-CoV-2, and only 7 had received one dose.
In the study, published yesterday in JAMA, the researchers studied MIS-C patients 12 to 18 years old hospitalized or admitted to 1 of 41 pediatric intensive care units (PICUs) from Sep 1 to Oct 31, 2021. Over the summer, France experienced a fourth wave of COVID-19 caused by the Delta (B1617.2) variant, which peaked in August. At the same time, French officials recommended COVID-19 vaccination of children 12 years and older.
Of the 107 teens, 33 (31%) were eligible for two doses of COVID-19 vaccine, 0 had been fully vaccinated, 7 (6.5%) had been given one dose, and 26 (24.3%) were unvaccinated. Median patient age was 13.7 years. Of adolescents eligible for vaccination, 29 (88%) were admitted to a PICU, and 27 (82%) were boys.
The hazard ratio (HR) for MIS-C was 0.09 after the first vaccine dose relative to unvaccinated adolescents. Sensitivity analyses yielded comparable results.
Median time from the first COVID-19 vaccine dose to MIS-C onset was 25 days, compared with, on average, 28 days between SARS-CoV-2 infection and MIS-C onset. The authors said that this finding suggests that most infections occurred before or shortly after the first vaccine dose, before a full immune response was mounted.
While the absence of MIS-C in fully vaccinated adolescents precluded calculation of a hazard ratio for that group, it suggested that two doses are needed for efficient protection, the authors said.
"The association between mRNA vaccination with MIS-C in younger children should be evaluated as vaccines are approved for use in children aged 5 to 11 years," the researchers wrote. "Close monitoring is required given the alert on myocarditis occurring in adolescents after COVID-19 mRNA vaccine."
Dec 20 JAMA research letter
COVID-19 breakthrough cases rose after Delta dominance, data show
New analysis from the Centers for Disease Control and Prevention published in NEJM Evidence suggests that vaccine protection from SARS-CoV-2 infection among all ages, and from death among older adults, waned with increasing time since vaccination after Delta (B1617.2) became the dominant strain in the United States.
The analysis was based on COVID-19 case and death data from 15 US jurisdictions from Jan 3, 2021 to Sep 4, 2021. The data used for these analyses excluded all cases and deaths before Aug 1, 2021, and chose Aug 1 as the cutoff, aligning with Delta variant dominance.
By Aug 1, case rates per 100,000 person-weeks among vaccinated Americans of all ages rose, with those vaccinated in January and February seeing the most breakthrough cases (168.8), and those vaccinated in July seeing the fewest (63.1). The median time to infection after vaccination was between 102 and 118 days.
"Across age groups and vaccine types, people who were vaccinated 6 months ago or longer (January-February) were 3.44 (3.36 to 3.53) times more likely to be infected and 1.70 (1.29 to 2.23) times more likely to die from COVID-19 than people vaccinated recently in July 2021," the authors found.
Older adults were more likely to die from breakthrough cases, with Pfizer recipients at highest risk. Pfizer-BioNTech vaccine recipients ages 65 to 79 and those 80 years or older had higher death rates among those vaccinated earlier in the year compared with those vaccinated in July, the authors said.
The authors suggest these data support the extensive use of booster doses for vaccinated Americans, especially for those who received the Johnson & Johnson vaccine, and for older Americans who were initially vaccinated with Pfizer early in 2021.
Dec 20 NEJM Evidence study
H5N1 avian flu strikes poultry and wild birds in and around Denmark
Denmark reported a highly pathogenic H5N1 avian flu outbreak at a game bird farm near Viborg in the north central part of the country, according to a notification from the World Organization for Animal Health (OIE).
The outbreak began on Dec 18, when farm workers noticed deaths in birds. The facility houses pheasants and mallards. The virus killed 100 of 6,000 birds.
Also, animal health officials in the Faroe Islands, located between Norway and Iceland, detected H5N1 for the first time in wild birds. The virus was confirmed in two different locations, Streymoy, the largest and most populous island, and Eysturoy, the second-largest island. Both detections involved seabirds found dead in September.
Dec 20 OIE report on H5N1 in Denmark
Dec 20 OIE report on H5N1 in the Faroe Islands
