Long-Term Antibody Response to SARS-CoV-2 in Children

Almost 2 years into the pandemic and with vaccination of children significantly lagging behind adults, long-term pediatric humoral immune responses to SARS-CoV-2 are understudied. The C19.CHILD Hamburg (COVID-19 Child Health Investigation of Latent Disease) Study is a prospective cohort study designed to identify and follow up children and their household contacts infected in the early 2020 first wave of SARS-CoV-2. We screened 6113 children < 18 years by nasopharyngeal swab-PCR in a low-incidence setting after general lockdown, from May 11 to June 30, 2020. A total of 4657 participants underwent antibody testing. Positive tests were followed up by repeated PCR and serological testing of all household contacts over 6 months. In total, the study identified 67 seropositive children (1.44%); the median time after infection at first presentation was 83 days post-symptom onset (PSO). Follow-up of household contacts showed less than 100% seroprevalence in most families, with higher seroprevalence in families with adult index cases compared to pediatric index cases (OR 1.79, P = 0.047). Most importantly, children showed sustained seroconversion up to 9 months PSO, and serum antibody concentrations persistently surpassed adult levels (ratio serum IgG spike children vs. adults 90 days PSO 1.75, P < 0.001; 180 days 1.38, P = 0.01; 270 days 1.54, P = 0.001). In a low-incidence setting, SARS-CoV-2 infection and humoral immune response present distinct patterns in children including higher antibody levels, and lower seroprevalence in families with pediatric index cases. Children show long-term SARS-CoV-2 antibody responses. These findings are relevant to novel variants with increased disease burden in children, as well as for the planning of age-appropriate vaccination strategies.

Cloning and characterization of DNA complementary to the measles virus mRNA encoding hemagglutinin and matrix protein

Since cloning and characterization of DNA complementary to measles virus mRNA encoding for the nucleocapsid protein (M. Gorecki and S. Rozenblatt, Proc, Natl. Acad, Sci, U.S.A. 77:3686--3690, 1980), two additional measles-specific clones containing different classes of sequences have been characterized. The cloned plasmids contain inserts of 480 and 530 base pairs as shown by agarose gel electrophoresis and electron microscopy. The sizes of the mRNA species complementary to these inserts are 1,700 and 1,550 nucleotides, respectively as determined by the Northern technique. The cloned DNA fragments were further identified as reverse transcripts of the mRNA coding for the glycoprotein and matrix protein of measles virus. The major cell-free translation products of mRNA selected by hybridization to the individual cloned DNAs comigrated with the 70K in vitro products and matrix proteins. One of the cell-free translation products (70K) was also immunoprecipitated specifically with monoclonal antibodies against measles virus glycoprotein.