Early Insights from Statistical and Mathematical Modeling of Key Epidemiologic Parameters of COVID-19.

We report key epidemiologic parameter estimates for coronavirus disease identified in peer-reviewed publications, preprint articles, and online reports. Range estimates for incubation period were 1.8-6.9 days, serial interval 4.0-7.5 days, and doubling time 2.3-7.4 days. The effective reproductive number varied widely, with reductions attributable to interventions. Case burden and infection fatality ratios increased with patient age. Implementation of combined interventions could reduce cases and delay epidemic peak up to 1 month. These parameters for transmission, disease severity, and intervention effectiveness are critical for guiding policy decisions. Estimates will likely change as new information becomes available.

Younger ages at risk of Covid-19 mortality in communities of color.

More than 85% of Covid-19 mortality in high income countries is among people 65 years of age or older. Recent disaggregated data from the UK and US show that minority communities have increased mortality among younger age groups and in South Africa initial data suggest that the majority of deaths from Covid-19 are under 65 years of age. These observations suggest significant potential for increased Covid-19 mortality among younger populations in Africa and South Asia and may impact age-based selection of high-risk groups eligible for a future vaccine.

HIV Incidence and Risk Behaviours of People Who Inject Drugs in Bangkok, 1995-2012.

BACKGROUND: Three consecutive prospective studies were conducted among people who inject drugs (PWID) from May 1995 through June 2012 in Bangkok, Thailand. We examined data from these studies to evaluate HIV incidence and explore trends in risk behaviours. METHODS: We used data from a 1995-1998 cohort study, a 1999-2004 HIV vaccine trial, and a 2005-2012 HIV pre-exposure prophylaxis (PrEP) study to examine per-quarter trends in HIV incidence, using a restricted cubic spline function for time in a Poisson regression. We also examined temporal trends in HIV-associated risk behaviours. FINDINGS: HIV incidence declined from 5.7 per 100 person-years during the cohort study, to 2.7 per 100 person-years in the vaccine trial, to 0.7 per 100 person-years among PrEP study placebo recipients. Incidence peaked at 12.1 per 100 person-years in 1996 and declined to < 1 per 100 person-years during 2005-2012. Reports of injecting drugs and sharing needles also declined from the cohort study to the PrEP study (p < 0.0001). Heroin was the most common drug injected during the cohort study and the vaccine trial, but stimulants (e.g., methamphetamine) and sedatives (e.g., midazolam) were injected more often during the PrEP study. INTERPRETATION: HIV incidence among PWID declined during 2005-2012. Several factors likely contributed to the decline, including decreases in the frequency of injecting and sharing, improved access to HIV testing and antiretroviral therapy, and the use of PrEP. Expanding access to effective HIV prevention tools can hasten control of the HIV epidemic among PWID. FUNDING: The Bangkok Metropolitan Administration and U.S. Centers for Disease Control and Prevention, Division of HIV/AIDS Prevention.

US Centers for Disease Control and Prevention and Its Partners' Contributions to Global Health Security.

To achieve compliance with the revised World Health Organization International Health Regulations (IHR 2005), countries must be able to rapidly prevent, detect, and respond to public health threats. Most nations, however, remain unprepared to manage and control complex health emergencies, whether due to natural disasters, emerging infectious disease outbreaks, or the inadvertent or intentional release of highly pathogenic organisms. The US Centers for Disease Control and Prevention (CDC) works with countries and partners to build and strengthen global health security preparedness so they can quickly respond to public health crises. This report highlights selected CDC global health protection platform accomplishments that help mitigate global health threats and build core, cross-cutting capacity to identify and contain disease outbreaks at their source. CDC contributions support country efforts to achieve IHR 2005 compliance, contribute to the international framework for countering infectious disease crises, and enhance health security for Americans and populations around the world.

Contributions of the US Centers for Disease Control and Prevention in Implementing the Global Health Security Agenda in 17 Partner Countries.

The Global Health Security Agenda (GHSA), a partnership of nations, international organizations, and civil society, was launched in 2014 with a mission to build countries' capacities to respond to infectious disease threats and to foster global compliance with the International Health Regulations (IHR 2005). The US Centers for Disease Control and Prevention (CDC) assists partner nations to improve IHR 2005 capacities and achieve GHSA targets. To assess progress through these CDC-supported efforts, we analyzed country activity reports dating from April 2015 through March 2017. Our analysis shows that CDC helped 17 Phase I countries achieve 675 major GHSA accomplishments, particularly in the cross-cutting areas of public health surveillance, laboratory systems, workforce development, and emergency response management. CDC's engagement has been critical to these accomplishments, but sustained support is needed until countries attain IHR 2005 capacities, thereby fostering national and regional health protection and ensuring a world safer and more secure from global health threats.

Joint External Evaluation-Development and Scale-Up of Global Multisectoral Health Capacity Evaluation Process.

The Joint External Evaluation (JEE), a consolidation of the World Health Organization (WHO) International Health Regulations 2005 (IHR 2005) Monitoring and Evaluation Framework and the Global Health Security Agenda country assessment tool, is an objective, voluntary, independent peer-to-peer multisectoral assessment of a country's health security preparedness and response capacity across 19 IHR technical areas. WHO approved the standardized JEE tool in February 2016. The JEE process is wholly transparent; countries request a JEE and are encouraged to make its findings public. Donors (e.g., member states, public and private partners, and other public health institutions) can support countries in addressing identified JEE gaps, and implementing country-led national action plans for health security. Through July 2017, 52 JEEs were completed, and 25 more countries were scheduled across WHO's 6 regions. JEEs facilitate progress toward IHR 2005 implementation, thereby building trust and mutual accountability among countries to detect and respond to public health threats.

Burden and characteristics of HIV infection among female sex workers in Kampala, Uganda - a respondent-driven sampling survey.

BACKGROUND: Sex workers in Uganda are at significant risk for HIV infection. We characterized the HIV epidemic among Kampala female sex workers (FSW). METHODS: We used respondent-driven sampling to sample FSW aged 15+ years who reported having sold sex to men in the preceding 30 days; collected data through audio-computer assisted self-interviews, and tested blood, vaginal and rectal swabs for HIV, syphilis, neisseria gonorrhea, chlamydia trachomatis, and trichomonas vaginalis. RESULTS: A total of 942 FSW were enrolled from June 2008 through April 2009. The overall estimated HIV prevalence was 33% (95% confidence intervals [CI] 30%-37%) and among FSW 25 years or older was 44%. HIV infection is associated with low levels of schooling, having no other work, never having tested for HIV, self-reported genital ulcers or sores, and testing positive for neisseria gonorrhea or any sexually transmitted infections (STI). Two thirds (65%) of commercial sex acts reportedly were protected by condoms; one in five (19%) FSW reported having had anal sex. Gender-based violence was frequent; 34% reported having been raped and 24% reported having been beaten by clients in the preceding 30 days. CONCLUSIONS: One in three FSW in Kampala is HIV-infected, suggesting a severe HIV epidemic in this population. Intensified interventions are warranted to increase condom use, HIV testing, STI screening, as well as antiretroviral treatment and pre-exposure prophylaxis along with measures to overcome gender-based violence.

Overview, Control Strategies, and Lessons Learned in the CDC Response to the 2014-2016 Ebola Epidemic.

During 2014-2016, CDC, working with U.S. and international partners, mounted a concerted response to end the unprecedented epidemic of Ebola virus disease (Ebola) in West Africa. CDC's response, which was the largest in the agency's history, was directed simultaneously at controlling the epidemic in West Africa and strengthening preparedness for Ebola in the United States. Although experience in responding to approximately 20 Ebola outbreaks since 1976 had provided CDC and other international responders an understanding of the disease and how to stop its spread, the epidemic in West Africa presented new and formidable challenges. The initial response was slow and complicated for several reasons, including wide geographic spread of cases, poor public health and societal infrastructure, sociodemographic factors, local unfamiliarity with Ebola, and distrust of government and health care workers. In the United States, widespread public alarm erupted after Ebola cases were diagnosed in Dallas, Texas, and New York City, New York. CDC, in collaboration with its U.S. and international counterparts, applied proven public health strategies as well as innovative new approaches to help control the Ebola epidemic in West Africa and strengthen public health readiness in the United States. Lessons learned include the recognition that West African and other countries need effective systems to detect and stop infectious disease threats, the need for stronger international surge capacity for times when countries are overwhelmed by an outbreak, and the importance of improving infection prevention and control in health care settings. The activities summarized in this report would not have been possible without collaboration with many U.S. and international partners (http://www.cdc.gov/vhf/ebola/outbreaks/2014-west-africa/partners.html).

Population Pharmacokinetics and Pharmacodynamics of Lumefantrine in Young Ugandan Children Treated With Artemether-Lumefantrine for Uncomplicated Malaria.

BACKGROUND: The pharmacokinetics and pharmacodynamics of lumefantrine, a component of the most widely used treatment for malaria, artemether-lumefantrine, has not been adequately characterized in young children. METHODS: Capillary whole-blood lumefantrine concentration and treatment outcomes were determined in 105 Ugandan children, ages 6 months to 2 years, who were treated for 249 episodes of Plasmodium falciparum malaria with artemether-lumefantrine. RESULTS: Population pharmacokinetics for lumefantrine used a 2-compartment open model with first-order absorption. Age had a significant positive correlation with bioavailability in a model that included allometric scaling. Children not receiving trimethoprim-sulfamethoxazole with capillary whole blood concentrations <200 ng/mL had a 3-fold higher hazard of 28-day recurrent parasitemia, compared with those with concentrations >200 ng/mL (P = .0007). However, for children receiving trimethoprim-sulfamethoxazole, the risk of recurrent parasitemia did not differ significantly on the basis of this threshold. Day 3 concentrations were a stronger predictor of 28-day recurrence than day 7 concentrations. CONCLUSIONS: We demonstrate that age, in addition to weight, is a determinant of lumefantrine exposure, and in the absence of trimethoprim-sulfamethoxazole, lumefantrine exposure is a determinant of recurrent parasitemia. Exposure levels in children aged 6 months to 2 years was generally lower than levels published for older children and adults. Further refinement of artemether-lumefantrine dosing to improve exposure in infants and very young children may be warranted.

Public Health Surveillance: At the Core of the Global Health Security Agenda.

Global health security involves developing the infrastructure and capacity to protect the health of people and societies worldwide. The acceleration of global travel and trade poses greater opportunities for infectious diseases to emerge and spread. The International Health Regulations (IHR) were adopted in 2005 with the intent of proactively developing public health systems that could react to the spread of infectious disease and provide better containment. Various challenges delayed adherence to the IHR. The Global Health Security Agenda came about as an international collaborative effort, working multilaterally among governments and across sectors, seeking to implement the IHR and develop the capacities to prevent, detect, and respond to public health emergencies of international concern. When examining the recent West African Ebola epidemic as a case study for global health security, both strengths and weaknesses in the public health response are evident. The central role of public health surveillance is a lesson reiterated by Ebola. Through further implementation of the Global Health Security Agenda, identified gaps in surveillance can be filled and global health security strengthened.

Intimate Partner Violence and Adherence to HIV Pre-exposure Prophylaxis (PrEP) in African Women in HIV Serodiscordant Relationships: A Prospective Cohort Study.

BACKGROUND: Intimate partner violence (IPV) is associated with higher HIV incidence, reduced condom use, and poor adherence to antiretroviral therapy and other medications. IPV may also affect adherence to pre-exposure prophylaxis (PrEP). METHODS: We analyzed data from 1785 HIV-uninfected women enrolled in a clinical trial of PrEP among African HIV serodiscordant couples. Experience of verbal, physical, or economic IPV was assessed at monthly visits by face-to-face interviews. Low PrEP adherence was defined as clinic-based pill count coverage <80% or plasma tenofovir levels <40 ng/mL. The association between IPV and low adherence was analyzed using generalized estimating equations, adjusting for potential confounders. In-depth interview transcripts were examined to explain how IPV could impact adherence. RESULTS: Sixteen percent of women reported IPV during a median of 34.8 months of follow-up (interquartile range 27.0-35.0). Overall, 7% of visits had pill count coverage <80%, and 32% had plasma tenofovir <40 ng/mL. Women reporting IPV in the past 3 months had increased risk of low adherence by pill count (adjusted risk ratio 1.49, 95% confidence interval: 1.17 to 1.89) and by plasma tenofovir (adjusted risk ratio 1.51, 95% confidence interval: 1.06 to 2.15). Verbal, economic, and physical IPV were all associated with low adherence. However, the impact of IPV diminished and was not statistically significant 3 months after the reported exposure. In qualitative interviews, women identified several ways in which IPV affected adherence, including stress and forgetting, leaving home without pills, and partners throwing pills away. CONCLUSIONS: Women who reported recent IPV in the Partners PrEP Study were at increased risk of low PrEP adherence. Strategies to mitigate PrEP nonadherence in the context of IPV should be evaluated.

Rethinking Dosing Regimen Selection of Piperaquine for Malaria Chemoprevention: A Simulation Study.

BACKGROUND: The combination of short-acting dihydroartemisinin and long-acting piperaquine (DP) is among the first-line therapies for the treatment of uncomplicated Plasmodium falciparum malaria. Population pharmacokinetic models of piperaquine (PQ) based on data from acute treatment of young children can be used to predict exposure profiles of piperaquine under different DP chemoprevention regimens. The purpose of our study was to make such predictions in young children. METHODS: Based on a prior population pharmacokinetic model of PQ in young Ugandan children, we simulated capillary plasma concentration-time profiles (including their variability) of candidate chemoprevention regimens for a reference population of 1-2 year olds weighing at least 11 kg. Candidate regimens that were tested included monthly administration of standard therapeutic doses, bimonthly dosing, and weekly dosing (with and without a loading dose). RESULTS: Once daily doses of 320 mg for three days (960 mg total) at the beginning of each month are predicted to achieve an average steady-state trough capillary piperaquine concentration of 35 ng/mL, with 60% achieving a level of 30 ng/mL or higher. In contrast, weekly dosing of 320 mg (i.e., 33% higher amount per month) is predicted to approximately double the average steady-state trough concentration, increase the percent of children predicted to achieve 30 ng/mL or higher (94%), while at the same time lowering peak concentrations. Exposure at steady-state, reached at approximately 3 months of multiple dosing, is expected to be approximately 2-fold higher than exposure following initial dosing, due to accumulation. A loading dose improves early exposure, thereby reducing the risk of breakthrough infections at the initiation of chemoprevention. CONCLUSIONS: Once weekly chemoprevention of DP predicts favourable exposures with respect to both trough and peak concentrations. These predictions need to be verified, as well as safety evaluated, in field-based clinical studies of young children. Simulations based on prior knowledge provide a systematic information-driven approach to evaluate candidate DP chemopreventive regimens for future trial designs.

B cell sub-types following acute malaria and associations with clinical immunity.

BACKGROUND: Repeated exposure to Plasmodium falciparum is associated with perturbations in B cell sub-set homeostasis, including expansion atypical memory B cells. However, B cell perturbations immediately following acute malaria infection have been poorly characterized, especially with regard to their relationship with immunity to malaria. METHODS: To better understand the kinetics of B cell sub-sets following malaria, the proportions of six B cell sub-sets were assessed at five time points following acute malaria in four to 5 years old children living in a high transmission region of Uganda. B cell sub-set kinetics were compared with measures of clinical immunity to malaria-lower parasite density at the time of malaria diagnosis and recent asymptomatic parasitaemia. RESULTS: Atypical memory B cell and transitional B cell proportions increased following malaria. In contrast, plasmablast proportions were highest at the time of malaria diagnosis and rapidly declined following treatment. Increased proportions of atypical memory B cells were associated with greater immunity to malaria, whereas increased proportions of transitional B cells were associated with evidence of less immunity to malaria. CONCLUSIONS: These findings highlight the dynamic changes in multiple B cell sub-sets following acute, uncomplicated malaria, and how these sub-sets are associated with developing immunity to malaria.

Younger Age Predicts Failure to Achieve Viral Suppression and Virologic Rebound Among HIV-1-Infected Persons in Serodiscordant Partnerships.

BACKGROUND: Antiretroviral therapy (ART) markedly reduces the risk of HIV-1 transmission in serodiscordant partnerships. We previously found that younger age and higher CD4 counts were associated with delayed initiation of ART by HIV-1-infected partners in serodiscordant partnerships. Among those initiating ART, we sought to explore whether those same factors were associated with failure to achieve viral suppression. METHODS: In a prospective study of HIV-1-infected persons who had a known heterosexual HIV-1-uninfected partner in Kenya and Uganda [Partners Pre-Exposure Prophylaxis (PrEP) Study], we used Cox proportional hazards regression to evaluate correlates of viral nonsuppression (HIV-1 RNA >80 copies/ml). RESULTS: Of 1,035 HIV-1-infected participants initiating ART, 867 (84%) achieved viral suppression: 77% by 6 months and 86% by 12 months. Younger age [adjusted hazard ratio (aHR) 1.05 for every 5 years younger; p = .006], lower pretreatment CD4 count (aHR 1.26; p = .009 for ≤250 compared with >250 cells/µl), and higher pretreatment HIV-1 RNA quantity (aHR 1.21 per log10; p < .001) independently predicted failure to achieve viral suppression. Following initial viral suppression, 8.8% (76/867) experienced virologic rebound (HIV-1 RNA >200 copies/ml): 6.3% and 11.5% by 6 and 12 months after initial suppression, respectively. Age was the only factor associated with increased risk of virologic rebound (aHR 1.33 for every 5 years younger; p = .005). CONCLUSIONS: For HIV-1-infected persons in serodiscordant couples, younger age was associated with delayed ART initiation, failure to achieve viral suppression, and increased risk of virologic rebound. Motivating ART initiation and early adherence is a key to achieving and sustaining viral suppression.

Global health security: the wider lessons from the west African Ebola virus disease epidemic.

The Ebola virus disease outbreak in West Africa was unprecedented in both its scale and impact. Out of this human calamity has come renewed attention to global health security--its definition, meaning, and the practical implications for programmes and policy. For example, how does a government begin to strengthen its core public health capacities, as demanded by the International Health Regulations? What counts as a global health security concern? In the context of the governance of global health, including WHO reform, it will be important to distil lessons learned from the Ebola outbreak. The Lancet invited a group of respected global health practitioners to reflect on these lessons, to explore the idea of global health security, and to offer suggestions for next steps. Their contributions describe some of the major threats to individual and collective human health, as well as the values and recommendations that should be considered to counteract such threats in the future. Many different perspectives are proposed. Their common goal is a more sustainable and resilient society for human health and wellbeing.

Rapid response to Ebola outbreaks in remote areas - Liberia, July-November 2014.

West Africa is experiencing its first epidemic of Ebola virus disease (Ebola). As of February 9, Liberia has reported 8,864 Ebola cases, of which 3,147 were laboratory-confirmed. Beginning in August 2014, the Liberia Ministry of Health and Social Welfare (MOHSW), supported by CDC, the World Health Organization (WHO), and others, began systematically investigating and responding to Ebola outbreaks in remote areas. Because many of these areas lacked mobile telephone service, easy road access, and basic infrastructure, flexible and targeted interventions often were required. Development of a national strategy for the Rapid Isolation and Treatment of Ebola (RITE) began in early October. The strategy focuses on enhancing capacity of county health teams (CHT) to investigate outbreaks in remote areas and lead tailored responses through effective and efficient coordination of technical and operational assistance from the MOHSW central level and international partners. To measure improvements in response indicators and outcomes over time, data from investigations of 12 of 15 outbreaks in remote areas with illness onset dates of index cases during July 16-November 20, 2014, were analyzed. The times to initial outbreak alerts and durations of the outbreaks declined over that period while the proportions of patients who were isolated and treated increased. At the same time, the case-fatality rate in each outbreak declined. Implementation of strategies, such as RITE, to rapidly respond to rural outbreaks of Ebola through coordinated and tailored responses can successfully reduce transmission and improve outcomes.

Protective efficacy of prolonged co-trimoxazole prophylaxis in HIV-exposed children up to age 4 years for the prevention of malaria in Uganda: a randomised controlled open-label trial.

BACKGROUND: WHO recommends daily co-trimoxazole for children born to HIV-infected mothers from 6 weeks of age until breastfeeding cessation and exclusion of HIV infection. We have previously reported on the effectiveness of continuation of co-trimoxazole prophylaxis up to age 2 years in these children. We assessed the protective efficacy and safety of prolonging co-trimoxazole prophylaxis until age 4 years in HIV-exposed children. METHODS: We undertook an open-label randomised controlled trial alongside two observational cohorts in eastern Uganda, an area with high HIV prevalence, malaria transmission intensity, and antifolate resistance. We enrolled HIV-exposed infants between 6 weeks and 9 months of age and prescribed them daily co-trimoxazole until breastfeeding cessation and HIV-status confirmation. At the end of breastfeeding, children who remained HIV-uninfected were randomly assigned (1:1) to discontinue co-trimoxazole or to continue taking it up to age 2 years. At age 2 years, children who continued co-trimoxazole prophylaxis were randomly assigned (1:1) to discontinue or continue prophylaxis from age 2 years to age 4 years. The primary outcome was incidence of malaria (defined as the number of treatments for new episodes of malaria diagnosed with positive thick smear) at age 4 years. For additional comparisons, we observed 48 HIV-infected children who took continuous co-trimoxazole prophylaxis and 100 HIV-unexposed uninfected children who never received prophylaxis. We measured grade 3 and 4 serious adverse events and hospital admissions. All children were followed up to age 5 years and all analyses were by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00527800. FINDINGS: 203 HIV-exposed infants were enrolled between Aug 10, 2007, and March 28, 2008. After breastfeeding ended, 185 children were not infected with HIV and were randomly assigned to stop (n=87) or continue (n=98) co-trimoxazole up to age 2 years. At age 2 years, 91 HIV-exposed children who had remained on co-trimoxazole prophylaxis were randomly assigned to discontinue (n=46) or continue (n=45) co-trimoxazole from age 2 years to age 4 years. We recorded 243 malaria episodes (2·91 per person-years) in the 45 HIV-exposed children assigned to continue co-trimoxazole until age 4 years compared with 503 episodes (5·60 per person-years) in the 46 children assigned to stop co-trimoxazole at age 2 years (incidence rate ratio 0·53, 95% CI 0·39-0·71; p< 0·0001). There was no evidence of malaria incidence rebound in the year after discontinuation of co-trimoxazole in the HIV-exposed children who stopped co-trimoxazole at age 2 years, but incidence increased significantly in HIV-exposed children who stopped co-trimoxazole at age 4 years (odds ratio 1·78, 95% CI 1·19-2·66; p= 0·005). Incidence of grade 3 or 4 serious adverse events, hospital admissions, or deaths did not significantly differ between HIV-exposed, HIV-unexposed, and HIV-infected children.

Challenges in responding to the ebola epidemic - four rural counties, Liberia, August-November 2014.

The first cases of Ebola virus disease (Ebola) in West Africa were identified in Guinea on March 22, 2014. On March 30, the first Liberian case was identified in Foya Town, Lofa County, near the Guinean border. Because the majority of early cases occurred in Lofa and Montserrado counties, resources were concentrated in these counties during the first several months of the response, and these counties have seen signs of successful disease control. By October 2014, the epidemic had reached all 15 counties of Liberia. During August 27-September 10, 2014, CDC in collaboration with the Liberian Ministry of Health and Social Welfare assessed county Ebola response plans in four rural counties (Grand Cape Mount, Grand Bassa, Rivercess, and Sinoe, to identify county-specific challenges in executing their Ebola response plans, and to provide recommendations and training to enhance control efforts. Assessments were conducted through interviews with county health teams and health care providers and visits to health care facilities. At the time of assessment, county health teams reported lacking adequate training in core Ebola response strategies and reported facing many challenges because of poor transportation and communication networks. Development of communication and transportation network strategies for communities with limited access to roads and limited means of communication in addition to adequate training in Ebola response strategies is critical for successful management of Ebola in remote areas.