COVID-19: CDDEP publishes the world’s largest contact tracing study from India in Science
The Question: A study led by CDDEP, representing coordinated efforts between researchers from Princeton, University of California, Berkeley, Johns Hopkins Bloomberg School of Public Health, and the Government of Tamil Nadu and Andhra Pradesh, investigated disease transmission patterns in 575,071 individuals exposed to 84,965 confirmed cases of COVID-19, in one of the largest contact tracing studies to date.
The Main Findings: The study revealed infection probabilities that ranged from 4.7-10.7% for low-risk and high-risk contact types respectively, with same-age contacts having the greatest risk of infection. Contrary to what has been observed in higher-income countries, reported cases and deaths were concentrated in younger cohorts with case-fatality ratios spanning from 0.05% at ages 5-17 years to 16.6% at ages ≥85 years.
While 71 % of the infected persons did not transmit the disease to their contacts, a small percentage of those infected were responsible for the majority of the secondary cases. Furthermore, data on exposure settings revealed that the secondary attack rate was higher in the household 9.0% (7.5-10.5%), as compared to community 2.6% (1.6-3.9%) and healthcare 1.2% (0.0-5.1%) settings.
The role of children in transmission has been debated so far; however, this study revealed enhanced transmission risk between young children of the same age (0-14 years), implying that school closures and other non-pharmaceutical mitigation measures, may have undermined the role of young children in disease transmission.
The Implications: Appropriate mitigating measures need to be taken as schools open and resume their normal activities, in order to prevent schools from becoming COVID-19 hotspots. While the study speaks to the capacity of research emerging from India to help inform the global response to COVID-19, it highlights the urgent need for data analysis from low-resource countries to guide control measures and inform policy.
In the Media: The study’s findings and its implications in the public health context have been discussed in depth in several major international media outlets:
Huge Study of Coronavirus Cases in India Offers Some Surprises to Scientists – The New York Times
Largest study of COVID-19 transmission highlights essential role of super-spreaders – Los Angeles Times
Kids And Superspreaders Are Driving COVID-19 Cases In India, Huge Study Finds – NPR
Are children the biggest Covid-19 spreaders? – BBC News, World Service
Big contact-tracing study shows role of kids and superspreaders in coronavirus pandemic – CNN
Studies show: High prevalence of infection among children who were in contact with their own age group – The Hindustan Times
India Surge Driven by Super-Spreaders – Bloomberg
What a Positive Test Won’t Change About Trump and the Pandemic – The New Yorker
Other notable COVID-19 studies this week
Association of SARS-CoV-2 Test Status and Pregnancy. Researchers in Sweden investigated the association of a SARS-CoV-2 test with pregnancy outcomes in women presenting in labor at Karolinska University Hospital in Stockholm, Sweden, from March 25 to July 24, 2020. The study revealed a higher prevalence of preeclampsia (7.7% vs 4.3%), and lower prevalence of induction of labor (18.7% vs 29.6%), in individuals with a positive SARS-CoV-2 test. Similar to previous studies, no association was found with prevalence of preterm birth, Apgar scores and birth weight, implying that COVID-19 may be less severe in pregnancy than previous coronavirus infections. [JAMA]
Prevalence of SARS-CoV-2 antibodies in a large nationwide sample of patients on dialysis in the USA. Researchers conducting a cross-sectional seroprevalence study, including 28,503 randomly selected adult patients receiving dialysis in July 2020 from 1300 dialysis facilities across the USA, revealed that fewer than 10% of the US adult population formed antibodies against SARS-CoV-2, and fewer than 10% of those with antibodies were diagnosed. The significant variations in prevalence with respect to geography, ethnicity, poverty and population density, emphasize the urgent need for public health efforts aimed at curbing the spread of the virus among the highest-risk communities. [The Lancet]
Susceptibility to SARS-CoV-2 infection among children and adolescents compared with adults. A systematic review and meta-analysis reviewing evidence from 32 studies on the susceptibility to and transmission of SARS-CoV-2 among children and adolescents (n=41,640), compared with adults (n=268,945), revealed a lower susceptibility in children and adolescents; the pooled odds ratio of being an infected contact in children compared with adults was 0.56 (95% CI, 0.37 to 0.85). However, data were insufficient to conclude whether transmission of SARS-CoV-2 by children is lower than by adults and more studies are needed to determine their respective roles in disease transmission. [JAMA Pediatrics]
Drug Resistance, Global Health
Parental self-medication with antibiotics for children promotes antibiotic over-prescribing. Researchers in China conducted a cross-sectional survey between June 2017 and April 2018 in three provinces, analyzing data from 1275 parents who had self-medicated their children from a total of 9526 parents with children aged 0–13 years and found that parental self-medication with antibiotics (SMA) had an impact on subsequent prescription of antibiotics by doctors. Children with parental SMA were more likely to be prescribed antibiotics (OR = 7.79, 95% CI 5.74 to 10.58), including IV antibiotics (OR = 3.05, 95% CI 2.27 to 4.11]) than children without parental SMA. Considering SMA as one of the most dangerous inappropriate antibiotic use behaviors, the authors recommend appropriate health education for parents and discouragement of parents’ SMA behaviors by doctors. [Antimicrobial Resistance & Infection Control]
Pneumococcal Urinary Antigen Testing in United States Hospitals: A Missed Opportunity for Antimicrobial Stewardship. Findings from a retrospective cohort study of 159,894 adult patients admitted with community-acquired or healthcare-associated pneumonia to 170 US hospitals between 2010 and 2015 revealed that urinary antigen testing (UAT) for antibiotic de-escalation in pneumococcal infections is not ordered routinely in cases of pneumonia, even in intensive care unit (ICU); 15.5% of the patients had UAT performed (18.4% ICU and 15.3% of non-ICU patients). Among patients initially treated with broad-spectrum antibiotics, UAT-positive patients more often had coverage narrowed (38.4% vs 17.0% UAT-negative and 14.6% untested patients, P < .001). Hospital rate of UAT was strongly correlated with de-escalation following a positive test and a positive UAT result was associated with less frequent resistant organisms, implying that increasing UAT and narrowing therapy after a positive UAT result represent opportunities for boosting antimicrobial stewardship. [Clinical Infectious Diseases]
Recommendations for antibacterial therapy in adults with COVID-19. Dutch experts examined up to date evidence on the risk of bacterial infections in hospitalized COVID-19 patients, the associated bacterial pathogens, as well as, the available diagnosis and treatment options. According to the review, 3.5% of COVID-19 patients presented with bacterial co-infection upon admission, while 15% eventually developed bacterial secondary infections during hospitalization. The experts’ recommendation was to restrict antibiotic use, especially upon admission and to concentrate efforts on performing the appropriate diagnostic tests which would ultimately guide therapeutic options. Other recommendation included treatment discontinuation when diagnostic evidence doesn’t support involvement of bacterial pathogens after 48 hours, and a five day treatment for suspected bacterial respiratory infection followed by improvement indicators. In face of limited, or no evidence to answer key clinical questions, large epidemiological studies are needed to prevent unnecessary antibiotic use in COVID-19 patients. [Clinical Microbiology and Infection]
HPV Vaccination and the Risk of Invasive Cervical Cancer. A team of investigators in Sweden conducted a population-based cohort study using data from a health registry, in order to assess the association between HPV vaccination and the subsequent risk of invasive cervical cancer in a cohort of 1,672,983 girls and women between the ages of 10 to 30, from 2006 to 2017. Age-adjusted incidence rate ratio (IRR) for the comparison of the vaccinated population with the unvaccinated population was 0.51 (95% CI 0.32 to 0.82) When adjusting for all covariates, IRR was 0.12 (95% CI, 0.00 to 0.34) among women who had been vaccinated before the age of 17 years and 0.47 (95% CI, 0.27 to 0.75) among women who had been vaccinated at the age of 17 to 30 years, implying that the reduction in the incidence of invasive cervical cancer was more pronounced among women who were vaccinated at a younger age. [NEJM]