CalScope: Monitoring SARS-CoV-2 Seroprevalence from Vaccination and Prior Infection in Adults and Children in California May 2021 to July 2021

ImportanceUnderstanding how SARS-CoV-2 seroprevalence varies regionally across California is critical to the public health response to the pandemic. ObjectiveTo estimate how many Californians have antibodies against SARS-CoV-2 from prior infection or vaccination. DesignWave 1 of CalScope: a repeated cross-sectional serosurvey of adults and children enrolled between April 20, 2021 and June 16, 2021. SettingA population-based random sample of households in seven counties in California (Alameda, El Dorado, Kern, Los Angeles, Monterey, San Diego, and Shasta) were invited to complete an at-home SARS-CoV-2 antibody test and survey instrument. ParticipantsInvitations were sent to 200,000 randomly selected households in the seven counties. From each household, 1 adult (18 years and older) and 1 child (aged 6 months to 17 years) could enroll in the study. There were no exclusion criteria. Main Outcome(s) and MeasuresAll specimens were tested for antibodies against the nucleocapsid and spike proteins of SARS-CoV-2. The primary outcome was serostatus category, which was determined based on antibody test results and self-reported vaccination status: seronegative, antibodies from infection only, antibodies from infection and vaccination, and antibodies from vaccination alone. We used inverse probability of selection weights and iterative proportional fitting to account for non-response. Results11,161 households enrolled in wave 1 of CalScope, with 7,483 adults and 1,375 children completing antibody testing. As of June 2021, 27% (95%CI [23%, 31%]) of adults and 30% (95%CI [24%, 36%]) of children had evidence of prior SARS-CoV-2 infection; 33% (95%CI [28%, 37%]) of adults and 57% (95%CI [48%, 66%]) of children were seronegative. Serostatus varied regionally. Californians 65 years or older were most likely to have antibodies from vaccine alone (59%; 95%CI [48%, 69%]) and children between 5-11 years old were most likely to have antibodies from prior infection alone (36%; 95%CI [21%, 52%]). Conclusions and RelevanceAs of June 2021, a third of adults in California and most children under 18 remained seronegative. Seroprevalence varied regionally and by demographic group, suggesting that some regions or populations might remain more vulnerable to subsequent surges than others. Key PointsO_ST_ABSQuestionC_ST_ABSWhat is the prevalence of vaccine and infection derived antibodies against SARS-CoV-2 in adults and children in California? FindingsIn this population-based serosurvey that included 11,161 households, as of June 2021, 33% of adults and 57% of children were seronegative; 18% of adults and 26% of children had antibodies from infection alone; 9% of adults and 5% of children had antibodies from both infection and vaccination; and 41% of adults and 13% of children had antibodies from vaccination alone. MeaningSerostatus varied considerably across geographic regions, suggesting that certain areas might be at increased risk for future COVID-19 surges.

Utility of a multiplex real-time polymerase chain reaction for combined detection and serotyping of dengue virus in paediatric patients hospitalised with severe dengue: A report from Chennai.

Objective: Molecular detection and serotyping are rapid, sensitive and accurate techniques for early diagnosis of paediatric dengue. The present study evaluates multiplex real-time polymerase chain reaction (PCR) for diagnosis of dengue virus in children hospitalised with severe dengue (SD) and attempts to establish an association of clinical severity with specific serotypes. Methods: Four hundred and eighty-five samples were received from hospitalised paediatric patients with suspected dengue from March 2019 to February 2020. Multiplex real time PCR was employed for diagnosis. An in-house real-time PCR that combined diagnosis and serotyping was established. Non-structural protein 1 (NS1) assay and real-time PCR were assessed for their accuracy in diagnosing severe paediatric dengue. Results: Three hundred and twenty-five (67%) patients were positive for dengue RNA by real-time PCR. All four serotypes were identified throughout the year; dengue serotype 2 (DEN-2) was predominant (61%) followed by DEN-3, 20%. Compared to the commonly used NS1 testing, multiplex real-time PCR showed greater sensitivity in diagnosing SD. Conclusions: Compared to NS1, multiplex real-time PCR is a rapid and accurate diagnostic test for children hospitalised with SD. DEN-2 was the predominant serotype in severe cases. Continued surveillance of serotypes should be carried out year-round in endemic areas.

A serological assay to detect SARS-CoV-2 antibodies in at-home collected finger-prick dried blood spots

Accurate surveillance of coronavirus disease 2019 (COVID-19) incidence requires large-scale testing of the population. Current testing methods require in-person collection of biospecimens by a healthcare worker, limiting access of individuals who do not have access to testing facilities while placing both patients and healthcare workers at risk of exposure to infection. We report the development and validation of a at-home finger-prick dried blood spot collection kit and an analysis method. We demonstrated 100% sensitivity and specificity using at-home collected specimens across the US. Such methods may facilitate the conduct of unbiased serosurveys within hard to reach populations and help reduce the sample collection burden of serological testing on both health care systems and individuals alike.

Group A rotavirus gastroenteritis in older children and adults at a hospital in southern India.

There is limited data on the spectrum and prevalence of rotavirus genotypes in older children and adults in Asia. This pilot study conducted between November 2012 and April 2013 tested for rotavirus in older children (>12 years of age), and adults with gastroenteritis from southern India. Stool samples from patients who were hospitalized or attended out-patient units with diarrhea were screened for rotavirus using Premier™ Rotaclone(®). Confirmatory testing was by another antigen detection sandwich, in-house ELISA, based on capture by a polyclonal serum and VP6 PCR. Genotyping for VP7 and VP4 was done using hemi-nested PCRs for G- and P-types circulating in India. A total of 626 stool samples from older children and adults were screened and 52 (8.4%) were initially positive for rotavirus by antigen detection. A high proportion of samples (27/51) were found to be false positives on confirmatory testing. Of the 23 samples for which genotyping results were obtained, G1P[8] was the most common genotype. There was one each of G1P[6], G1P[4] and two strains of G9P[4] while one sample showed mixed genotypes of G2 and G9P[4]. This study shows that group A rotavirus is found in 3.8% of diarrheal specimens in older children and adults with gastroenteritis in southern India and that common genotypes circulate in children and adults.