To assess the household secondary infection risk (SIR) of B.1.1.7 (Alpha) and non-Alpha lineages of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among children.
Study design
During January to April 2021, we prospectively followed households with a SARS-CoV-2 infection. We collected questionnaires, serial nasopharyngeal swabs for reverse transcription polymerase chain reaction testing and whole genome sequencing, and serial blood samples for serology testing. We calculated SIRs by primary case age (pediatric vs adult), household contact age, and viral lineage. We evaluated risk factors associated with transmission and described symptom profiles among children.
Results
Among 36 households with pediatric primary cases, 21 (58%) had secondary infections. Among 91 households with adult primary cases, 51 (56%) had secondary infections. SIRs among pediatric and adult primary cases were 45% and 54%, respectively (OR, 0.79; 95% CI, 0.41-1.54). SIRs among pediatric primary cases with Alpha and non-Alpha lineage were 55% and 46%, respectively (OR, 1.52; 95% CI, 0.51-4.53). SIRs among pediatric and adult household contacts were 55% and 49%, respectively (OR, 1.01; 95% CI, 0.68-1.50). Among pediatric contacts, no significant differences in the odds of acquiring infection by demographic or household characteristics were observed.
Conclusions
Household transmission of SARS-CoV-2 from children and adult primary cases to household members was frequent. The risk of secondary infection was similar among child and adult household contacts. Among children, household transmission of SARS-CoV-2 and the risk of secondary infection was not influenced by lineage. Continued mitigation strategies (eg, masking, physical distancing, vaccination) are needed to protect at-risk groups regardless of virus lineage circulating in communities.
Keywords
alpha variant
children
COVID-19
household transmission
Abbreviations
CDC
US Centers for Disease Control and Prevention
COVID-19
Coronavirus disease 2019
GEE
Generalized estimating equation
NP
Nasopharyngeal
RT-PCR
Reverse transcription polymerase chain reaction
SARS-CoV-2
Severe acute respiratory syndrome coronavirus 2
SIR
Secondary infection risk
VOC
Variant of concern
Cited by (0)
The investigation was funded by the US CDC. The investigation was supported by the County of San Diego Health and Human Services Agency, California Department of Public Health, Colorado Department of Public Health and Environment, and Tri-County Health Department. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the CDC. The authors declare no conficts of interest.
