Age-specific SARS-CoV-2 transmission differed from human rhinovirus in households during the early COVID-19 pandemic.

OBJECTIVES: Children are generally considered main drivers of transmission for respiratory viruses, but the emergence of SARS-CoV-2 challenged this paradigm. Human rhinovirus (RV) continued to co-circulate throughout the pandemic, allowing for direct comparison of age-specific infectivity and susceptibility within households between these viruses during a time of low SARS-CoV-2 population immunity. METHODS: Households with children were prospectively monitored for ≥23 weeks between August 2020 and July 2021. Upon onset of respiratory symptoms in a household, an outbreak study was initiated, including questionnaires and repeated nasal self-sampling in all household members. Swabs were tested by PCR. Age-stratified within-household secondary attack rates (SARs) were compared between SARS-CoV-2 and RV. RESULTS: 307 households participated including 582 children and 627 adults. Overall SAR was lower for SARS-CoV-2 than for RV (aOR 0.55) and age-distributions differed between both viruses (p<0.001). Following household exposure, children were significantly less likely to become infected with SARS-CoV-2 compared to RV (aOR 0.16), whereas this was opposite in adults (aOR 1.71). CONCLUSION: In households, age-specific susceptibility to SARS-CoV-2 and RV differs and drives differences in household transmission between these pathogens. This highlights the importance of characterizing age-specific transmission risks, particularly for emerging infections, to guide appropriate infection control interventions.

Long term sequelae after SARS-CoV-2 infection in children: a household study.

BACKGROUND: In children persistent symptoms after SARS-CoV-2 infection have been reported, however, duration and characteristics of symptoms in previously healthy children remain unclear. Therefore this study aimed to evaluate persisting symptoms in children at 6 and 12 months after a SARS-CoV-2 infection. METHODS: In this prospective cohort study households with a confirmed SARS-CoV-2 positive outbreak were matched 1:1 to household controls from SARS-CoV-2 negative outbreaks. These households completed questionnaires at 6 and 12 months on the presence and severity of SARS-CoV-2 related symptoms, general well-being/functioning, cognition, persisting symptoms and quality of life. FINDINGS: None of the children who had a SARS-CoV-2 infection during the study reported persistent symptoms at 6 and 12 months after infection, whereas almost 8% of the children with a negative RT-PCR test during the study reported symptoms such as coughing and mild fever, however, no significant differences were found. In addition, for all other outcomes, no differences were observed between the two groups. TAKE HOME MESSAGE: Post-acute sequelae of mild SARS-CoV-2 infections appears to be uncommon in previously healthy children.

Longitudinal Household Assessment of Respiratory Illness in Children and Parents During the COVID-19 Pandemic.

Importance: In the early COVID-19 pandemic, SARS-CoV-2 testing was only accessible and recommended for symptomatic persons or adults. This restriction hampered assessment of the true incidence of SARS-CoV-2 infection in children as well as detailed characterization of the SARS-CoV-2 disease spectrum and how this spectrum compared with that of other common respiratory illnesses. Objective: To estimate the community incidence of SARS-CoV-2 infection in children and parents and to assess the symptoms and symptom severity of respiratory illness episodes involving SARS-CoV-2-positive test results relative to those with SARS-CoV-2-negative test results. Design, Setting, and Participants: This cohort study randomly selected Dutch households with at least 1 child younger than 18 years. A total of 1209 children and adults from 307 households were prospectively followed up between August 25, 2020, and July 29, 2021, covering the second and third waves of the COVID-19 pandemic. Participation included SARS-CoV-2 screening at 4- to 6-week intervals during the first 23 weeks of participation (core study period; August 25, 2020, to July 29, 2021). Participants in all households finishing the core study before July 1, 2021, were invited to participate in the extended follow-up and to actively report respiratory symptoms using an interactive app until July 1, 2021. At new onset of respiratory symptoms or a SARS-CoV-2 positive test result, a household outbreak study was initiated, which included daily symptom recording, repeated polymerase chain reaction testing (nose-throat swabs and saliva and fecal samples), and SARS-CoV-2 antibody measurement (paired dried blood spots) in all household members. Outbreaks, households, and episodes of respiratory illness were described as positive or negative depending on SARS-CoV-2 test results. Data on participant race and ethnicity were not reported because they were not uniformly collected in the original cohorts and were therefore not representative or informative. Exposures: SARS-CoV-2-positive and SARS-CoV-2-negative respiratory illness episodes. Main Outcomes and Measures: Age-stratified incidence rates, symptoms, and symptom severity for SARS-CoV-2-positive and SARS-CoV-2-negative respiratory illness episodes. Results: Among 307 households including 1209 participants (638 female [52.8%]; 403 [33.3%] aged <12 years, 179 [14.8%] aged 12-17 years, and 627 [51.9%] aged ≥18 years), 183 household outbreaks of respiratory illness were observed during the core study and extended follow-up period, of which 63 (34.4%) were SARS-CoV-2 positive (59 outbreaks [32.2%] during the core study and 4 outbreaks [2.2%] during follow-up). SARS-CoV-2 incidence was similar across all ages (0.24/person-year [PY]; 95% CI, 0.21-0.28/PY). Overall, 33 of 134 confirmed SARS-CoV-2 episodes (24.6%) were asymptomatic. The incidence of SARS-CoV-2-negative respiratory illness episodes was highest in children younger than 12 years (0.94/PY; 95% CI, 0.89-0.97/PY). When comparing SARS-CoV-2-positive vs SARS-CoV-2-negative respiratory illness episodes in children younger than 12 years, no differences were observed in number of symptoms (median [IQR], 2 [2-4] for both groups), symptom severity (median [IQR] maximum symptom severity score, 6 [4-9] vs 7 [6-13]), or symptom duration (median [IQR], 6 [5-12] days vs 8 [4-13] days). However, among adults, SARS-CoV-2-positive episodes had a significantly higher number (median [IQR], 6 [4-8] vs 3 [2-4]), severity (median [IQR] maximum symptom severity score, 15 [9-19] vs 7 [6-11]), and duration (median [IQR] 13 [8-29] days vs 5 [3-11] days; P < .001 for all comparisons) of symptoms vs SARS-CoV-2-negative episodes. Conclusions and Relevance: In this cohort study, during the first pandemic year when mostly partial or full in-person learning occurred, the SARS-CoV-2 incidence rate in children was substantially higher than estimated from routine testing or seroprevalence data and was similar to that of adult household members. Unlike in unvaccinated adults, SARS-CoV-2 symptoms and symptom severity in children were similar to other common respiratory illnesses. These findings may prove useful when developing pediatric COVID-19 vaccine recommendations.

High Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Household Transmission Rates Detected by Dense Saliva Sampling.

BACKGROUND: Understanding the dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) household transmission is important for adequate infection control measures in this ongoing pandemic. METHODS: Households were enrolled upon a polymerase chain reaction-confirmed index case between October and December 2020, prior to the coronavirus disease 2019 vaccination program. Saliva samples were obtained by self-sampling at days 1, 3, 5, 7, 10, 14, 21, 28, 35, and 42 from study inclusion. Nasopharyngeal swabs (NPS) and oropharyngeal swabs (OPS) were collected by the research team at day 7 and capillary blood samples at day 42. Household secondary attack rate (SAR) and per-person SAR were calculated based on at least 1 positive saliva, NPS, OPS, or serum sample. Whole genome sequencing was performed to investigate the possibility of multiple independent SARS-CoV-2 introductions within a household. RESULTS: Eighty-five households were included consisting of 326 (unvaccinated) individuals. Comparable numbers of secondary cases were identified by saliva (133/241 [55.2%]) and serum (127/213 [59.6%]). The household SAR was 88.2%. The per-person SAR was 64.3%. The majority of the secondary cases tested positive in saliva at day 1 (103/150 [68.7%]). Transmission from index case to household member was not affected by age or the nature of their relationship. Phylogenetic analyses suggested a single introduction for the investigated households. CONCLUSIONS: Households have a pivotal role in SARS-CoV-2 transmission. By repeated saliva self-sampling combined with NPS, OPS, and serology, we found the highest SARS-CoV-2 household transmission rates reported to date. Salivary (self-) sampling of adults and children is suitable and attractive for near real-time monitoring of SARS-CoV-2 transmission in this setting.