Attractive targeted sugar baits (ATSBs) are a novel malaria control tool designed to target mosquitoes outdoors. We conducted a cluster-randomised trial to evaluate the impact of ATSBs on malaria indicators in Kenya. Seventy clusters (≥100 households/cluster) in Siaya county were randomly assigned (1:1) to intervention or control. Pyrethroid-only long-lasting insecticidal nets were distributed to all clusters, aiming for universal coverage. Two ATSBs containing dinotefuran were hung outside household structures in intervention clusters. ATSBs were monitored every two months and replaced every six months over two years. Three consecutive cohorts of randomly selected children (1- < 15 years) were enrolled, aiming to accrue 1,260 person-years over two years of follow-up. Incidence of clinical malaria (fever with a positive malaria test) was the primary outcome. A multilevel Poisson regression model was applied, with clusters as a random intercept and study arm as a fixed effect. Secondary outcomes were malaria prevalence in community residents (≥1 month), and parity of mosquitos captured through human landing catches. In March 2022, ATSBs were delivered to 33,180 of 33,419 (99.3%) household structures in intervention clusters. Overall, 268,268 ATSBs were deployed over two years. Of 2,962 cohort children enrolled (intervention = 1,497; control = 1,465), 2,869 (96.9%) were included in the primary analysis (intervention = 1,461; control = 1,408), contributing 1,445 person-years of follow-up. Malaria incidence was 1.32 episodes per person-years in the intervention arm versus 1.20 in the control (unadjusted incidence rate ratio 1.11; 95% CI: 0.75-1.65; p = 0.598). Of 7,488 community residents surveyed (intervention = 3,760; control = 3,728), 1,474 (39.2%) intervention and 1,461 (39.2%) control participants tested positive for malaria (unadjusted odds ratio [OR] 0.98; 95% CI: 0.60-1.59; p = 0.93). Of 6,457 female anopheles mosquitoes collected (intervention = 4,058; control = 2,399), 3,579 (88.2%) intervention and 1,973 (82.2%) control mosquitoes were parous (OR 1.34; 95% CI: 0.91-1.99; p = 0.14). In Kenya, we found no evidence that ATSBs reduced clinical malaria incidence, malaria prevalence, or vector parity. Trial registration Clinicaltrials.gov (NCT05219565), 22 January 2022.

OBJECTIVES: We sought to quantify the proportion of contacts reported by persons with COVID-19 through a short message service (SMS)-linked survey in comparison to the proportion of contacts reported during a follow-up phone-interview. We also sought to assess improvement in contact tracing timeliness associated with sending SMS-linked surveys. STUDY DESIGN: During December 4-15, 2020, persons identified as COVID-19 cases whose data was entered into Marin County's contact tracing database on even days received a SMS-linked survey and persons whose data was entered on odd days did not; all were called for case investigation and contact tracing. Chi-square test and Fisher's exact test were used to compare demographic data. Chi-square test was used to contrast categorical outcomes, and Wilcoxon's rank-sum test was used for continuous outcomes. RESULTS: Among 350 SMS-linked survey recipients, 85 (24%) responded and 4 (1%) reported contacts using the survey; an additional 303 contacts were reported during phone interviews. Without phone interviews, 99% of reported contacts would have been missed. There was no meaningful difference between study arms in the proportion of contacts notified within 48 h. CONCLUSIONS: This SMS-linked survey had low participation and was not useful for identifying contacts. Phone interviews remained crucial for COVID-19 contact tracing.

IMPORTANCE: Contact tracing is a multistep process to limit SARS-CoV-2 transmission. Gaps in the process result in missed opportunities to prevent COVID-19. OBJECTIVE: To quantify proportions of cases and their contacts reached by public health authorities and the amount of time needed to reach them and to compare the risk of a positive COVID-19 test result between contacts and the general public during 4-week assessment periods. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study took place at 13 health departments and 1 Indian Health Service Unit in 11 states and 1 tribal nation. Participants included all individuals with laboratory-confirmed COVID-19 and their named contacts. Local COVID-19 surveillance data were used to determine the numbers of persons reported to have laboratory-confirmed COVID-19 who were interviewed and named contacts between June and October 2020. MAIN OUTCOMES AND MEASURES: For contacts, the numbers who were identified, notified of their exposure, and agreed to monitoring were calculated. The median time from index case specimen collection to contact notification was calculated, as were numbers of named contacts subsequently notified of their exposure and monitored. The prevalence of a positive SARS-CoV-2 test among named and tested contacts was compared with that jurisdiction's general population during the same 4 weeks. RESULTS: The total number of cases reported was 74 185. Of these, 43 931 (59%) were interviewed, and 24 705 (33%) named any contacts. Among the 74 839 named contacts, 53 314 (71%) were notified of their exposure, and 34 345 (46%) agreed to monitoring. A mean of 0.7 contacts were reached by telephone by public health authorities, and only 0.5 contacts per case were monitored. In general, health departments reporting large case counts during the assessment (≥5000) conducted smaller proportions of case interviews and contact notifications. In 9 locations, the median time from specimen collection to contact notification was 6 days or less. In 6 of 8 locations with population comparison data, positive test prevalence was higher among named contacts than the general population. CONCLUSIONS AND RELEVANCE: In this cross-sectional study of US local COVID-19 surveillance data, testing named contacts was a high-yield activity for case finding. However, this assessment suggests that contact tracing had suboptimal impact on SARS-CoV-2 transmission, largely because 2 of 3 cases were either not reached for interview or named no contacts when interviewed. These findings are relevant to decisions regarding the allocation of public health resources among the various prevention strategies and for the prioritization of case investigations and contact tracing efforts.