Association Between Antibodies That Bind Epstein-Barr Virus (EBV) gp350 and gH/gL and Shedding of EBV in Saliva From Nasopharyngeal Carcinoma Multiplex Family Members in Taiwan.

Elevated levels of Epstein-Barr virus (EBV) gp350 and gH/gL antibodies have been associated with a lower risk of developing nasopharyngeal carcinoma (NPC), although the evidence remains inconclusive and unexplained. We conducted a longitudinal study within a high-risk Taiwanese cohort, analyzing total immunoglobulin against EBV-gp350 and -gH/gL in blood and EBV DNA shedding in saliva. Contrary to our hypothesis-that elevated levels of antibodies previously shown to be associated with a lower NPC risk should result in a decrease in EBV shedding in saliva-higher anti-gp350 antibodies at baseline were significantly associated with detectable EBV DNA in saliva at follow-up (odds ratio [OR], 1.99 [95% confidence interval {CI}, 1.03-3.97]; P = .04). Higher anti-EBV-gH/gL antibodies at baseline were not significantly associated with risk of detectable EBV DNA at follow-up (OR, 0.69 [95% CI, .35-1.32]; P = .26). These findings underscore the complexity of virus-host interactions and emphasize the need for further investigations into their role in EBV-associated diseases.

A surveillance study of cancer incidence and mortality among young adults in Costa Rica.

Background: There has been an increase in certain cancers among young adults (YA) aged 20-39, particularly in Latin America. This is the first study to examine cancer incidence and mortality in YA in Costa Rica, focusing on sex-specific patterns. Methods: Invasive cancer cases (excluding non-melanoma skin cancer) in YA from 2006 to 2015 were obtained from the Costa Rican National Registry of Tumors. Utilising SEER∗Stat software, age-standardized incidence rates (IRs) and incidence rate ratios (IRRs) were calculated. Trends and annual percent changes (APCs) in IRs were estimated using the Joinpoint regression analysis program. Cancer deaths from 2000 to 2021 were obtained from the Costa Rican National Institute of Statistics and Census. Age-standardised mortality rates were calculated using STATA®17. Findings: YA comprised 10.7% of all invasive cancer cases diagnosed from 2006 to 2015. The age-standardized incidence rate (ASIR) of invasive cancer in YA was 50.9/100,000 person-years. The ASIR was twofold higher for females compared to males (IRR = 2.03, 95% CI:1.94, 2.13). This difference increased with age, peaking in the 35-39-year age group (IRR = 2.84, 95% CI:2.62, 3.10). Thyroid, breast, and cervical cancer were the most common in females. Testicular cancer was the most common in males. Leading causes of cancer-related deaths included cervical and breast cancer in females and stomach and brain/nervous system cancer in males. Interpretation: The study highlights sex-specific patterns in cancer incidence and mortality among YA in Costa Rica to increase understanding and improve cancer outcomes in this age group. Funding: This study was funded by the Intramural Research Program of the National Cancer Institute.

SARS-CoV-2 infection prior to vaccination amplifies Fc-mediated humoral profiles in an age-dependent manner.

Immunity acquired by vaccination following infection, termed hybrid immunity, has been shown to confer enhanced protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by enhancing the breadth and potency of immune responses. Here, we assess Fc-mediated humoral profiles in hybrid immunity and their association with age and vaccine type. Participants are divided into three groups: infection only, vaccination only, and vaccination following infection (i.e., hybrid immunity). Using systems serology, we profile humoral immune responses against spikes and subdomains of SARS-CoV-2 variants. We find that hybrid immunity is characterized by superior Fc receptor binding and natural killer (NK) cell-, neutrophil-, and complement-activating antibodies, which is higher than what can be expected from the sum of the vaccination and infection. These differences between hybrid immunity and vaccine-induced immunity are more pronounced in aged adults, especially for immunoglobulin (Ig)G1, IgG2, and Fcγ receptor-binding antibodies. Our findings suggest that vaccination strategies that aim to mimic hybrid immunity should consider age as an important modifier.

Meeting report: Considerations for trial design and endpoints in licensing therapeutic HPV16/18 vaccines to prevent cervical cancer.

Cervical cancer is a major cause of morbidity and mortality globally with a disproportionate impact on women in low- and middle-income countries. In 2021, the World Health Organization (WHO) called for increased vaccination, screening, and treatment to eliminate cervical cancer. However, even with widespread rollout of human papillomavirus (HPV) prophylactic vaccines, millions of women who previously acquired HPV infections will remain at risk for progression to cancer for decades to come. The development and licensing of an affordable, accessible therapeutic HPV vaccine, designed to clear or control carcinogenic HPV and/or to induce regression precancer could significantly contribute to the elimination efforts, particularly benefiting those who missed out on the prophylactic vaccine. One barrier to development of such vaccines is clarity around the regulatory pathway for licensure. In Washington, D.C. on September 12-13, 2023, a meeting was convened to provide input and guidance on trial design with associated ethical and regulatory considerations. This report summarizes the discussion and conclusions from the meeting. Expert presentation topics included the current state of research, potential regulatory challenges, WHO preferred product characteristics, modeling results of impact of vaccine implementation, epidemiology and natural history of HPV infection, immune responses related to viral clearance and/or precancer regression including potential biomarkers, and ethical considerations. Panel discussions were held to explore specific trial design recommendations to support the licensure process for two vaccine indications: (1) treatment of prevalent HPV infection or (2) treatment of cervical precancers. Discussion covered inclusion/exclusion criteria, study endpoints, sample size and power, safety, study length, and additional data needed, which are reported here. Further research of HPV natural history is needed to address identified gaps in regulatory guidance, especially for therapeutic vaccines intended to treat existing HPV infections.

A proteome-wide analysis unveils a core Epstein-Barr virus antibody signature of classic Hodgkin lymphoma across ethnically diverse populations.

Epstein-Barr virus (EBV) is an oncogenic virus associated with various malignancies, including classical Hodgkin lymphoma (cHL). Despite its known association, the specific role of humoral immune response to EBV remains poorly characterized in cHL. To address this, we conducted a study using a custom protein microarray to measure the antibody responses in cHL patients and matched healthy controls recruited from an East-Asian hospital-based case-control study. We identified 16 IgG antibodies significantly elevated in EBV-positive cHL compared with controls, defining an "East-Asian antibody signature of EBV-positive cHL." We evaluated responses against these 16 antibodies in a distinct European population, leveraging data from our previous European cHL case-control study from the UK, Denmark, and Sweden. A subset of antibodies (14/16, 87.5%) from the "East-Asian antibody signature of EBV-positive cHL" exhibited significant associations with cHL in the European population. Conversely, we assessed the "European antibody signature of EBV-positive cHL" identified in our prior study which consisted of 18 EBV antibodies (2 IgA, 16 IgG), in the East-Asian population. A subset of these antibodies (15/18, 83.3%) maintained significant associations with cHL in the East-Asian population. This cross-comparison of antibody signatures underscores the robust generalizability of EBV antibodies across populations. Five anti-EBV IgG antibodies (LMP-1, TK, BALF2, BDLF3, and BBLF1), found in both population-specific antibody signatures, represent a "core signature of EBV-positive cHL." Our findings suggest that the antibody responses targeting these core EBV proteins reflect a specific EBV gene expression pattern, serving as potential biomarkers for EBV-positive cHL independent of population-specific factors.

Differential long-term bivalent HPV vaccine cross-protection by variants in the Costa Rica HPV vaccine trial.

The AS04-adjuvanted human papillomavirus (HPV)16/18 vaccine, an L1-based vaccine, provides strong vaccine efficacy (VE) against vaccine-targeted type infections, and partial cross-protection to phylogenetically-related types, which may be affected by variant-level heterogeneity. We compared VE against incident HPV31, 33, 35, and 45 detections between lineages and SNPs in the L1 region among 2846 HPV-vaccinated and 5465 HPV-unvaccinated women through 11-years of follow-up in the Costa Rica HPV Vaccine Trial. VE was lower against HPV31-lineage-B (VE=60.7%;95%CI = 23.4%,82.8%) compared to HPV31-lineage-A (VE=94.3%;95%CI = 83.7%,100.0%) (VE-ratio = 0.64;95%CI = 0.25,0.90). Differential VE was observed at several lineage-associated HPV31-L1-SNPs, including a nonsynonymous substitution at position 6372 on the FG-loop, an important neutralization domain. For HPV35, the only SNP-level difference was at position 5939 on the DE-loop, with significant VE against nucleotide-G (VE=65.0%;95%CI = 28.0,87.8) but not for more the common nucleotide-A (VE=7.4%;95%CI = -34.1,36.7). Because of the known heterogeneity in precancer/cancer risk across cross-protected HPV genotype variants by race and region, our results of differential variant-level AS04-adjuvanted HPV16/18 vaccine efficacy has global health implications.

Kinetics of EBV antibody-based NPC risk scores in Taiwan NPC multiplex families.

Nasopharyngeal carcinoma (NPC) risk prediction models based on Epstein-Barr virus (EBV)-antibody testing have shown potential for screening of NPC; however, the long-term stability is unclear. Here, we investigated the kinetics of two EBV-antibody NPC risk scores within the Taiwan NPC Multiplex Family Study. Among 545 participants with multiple blood samples, we evaluated the stability of a 2-marker enzyme-linked immunosorbent assay score and 13-marker multiplex serology score using the intra-class correlation coefficient (ICC) by fitting a linear mixed model that accounted for the clustering effect of multiple measurements per subject and age. We also estimated the clustering of positive tests using Fleiss's kappa statistic. Over an average 20-year follow-up, the 2-marker score showed high stability over time, whereas the 13-marker score was more variable (p < .05). Case-control status is associated with the kinetics of the antibody response, with higher ICCs among cases. Positive tests were more likely to cluster within the same individual for the 2-marker score than the 13-marker score (p < .05). The 2-marker score had an increase in specificity from ~90% for single measurement to ~96% with repeat testing. The 13-marker score had a specificity of ~73% for a single measurement that increased to ~92% with repeat testing. Among individuals who developed NPC, none experienced score reversion. Our findings suggest that repeated testing could improve the specificity of NPC screening in high-risk NPC multiplex families. Further studies are required to determine the impact on sensitivity, establish optimal screening intervals, and generalize these findings to general population settings in high-risk regions.

COVID-19 and long-term impact on symptoms and Health-Related Quality of Life in Costa Rica: the RESPIRA cohort study.

BACKGROUND: Evidence continues to accumulate regarding the potential long-term health consequences of COVID-19 in the population. To distinguish between COVID-19-related symptoms and health limitations from those caused by other conditions, it is essential to compare cases with community controls using prospective data ensuring case-control status. The RESPIRA study addresses this need by investigating the lasting impact of COVID-19 on Health-related Quality of Life (HRQoL) and symptomatology in a population-based cohort in Costa Rica, thereby providing a robust framework for controlling HRQoL and symptoms. METHODS: The study comprised 641 PCR-confirmed, unvaccinated cases of COVID-19 and 947 matched population-based controls. Infection was confirmed using antibody tests on enrollment serum samples and symptoms were monitored monthly for 6 months post-enrolment. Administered at the 6-month visit (occurring between 6- and 2-months post-diagnosis for cases and 6 months after enrollment for controls), HRQoL and Self-Perceived Health Change were assessed using the SF-36, while brain fog, using three items from the Mental Health Inventory (MHI). Regression models were utilized to analyze SF-36, MHI scores, and Self-Perceived Health Change, adjusted for case/control status, severity (mild case, moderate case, hospitalized) and additional independent variables. Sensitivity analyses confirmed the robustness of the findings. RESULTS: Cases showed significantly higher prevalences of joint pain, chest tightness, and skin manifestations, that stabilized at higher frequencies from the fourth month post-diagnosis onwards (2.0%, 1.2%, and 0.8% respectively) compared to controls (0.9%, 0.4%, 0.2% respectively). Cases also exhibited significantly lower HRQoL than controls across all dimensions in the fully adjusted model, with a 12.4 percentage-point difference [95%CI: 9.4-14.6], in self-reported health compared to one year prior. Cases reported 8.0% [95%CI: 4.2, 11.5] more physical limitations, 7.3% [95%CI: 3.5, 10.5] increased lack of vitality, and 6.0% [95%CI: 2.4, 9.0] more brain fog compared to controls with similar characteristics. Undiagnosed cases detected with antibody tests among controls had HRQoL comparable to antibody negative controls. Differences were more pronounced in individuals with moderate or severe disease and among women. CONCLUSIONS: PCR-confirmed unvaccinated cases experienced prolonged HRQoL reductions 6 months to 2 years after diagnosis, this was particularly the case in severe cases and among women. Mildly symptomatic cases showed no significant long-term sequelae.

Statin use is not associated with inflammation among Chilean women of Mapuche and non-Mapuche ancestry with gallstones.

Aim: Statins are associated with lower risk of gallstones due to anti-inflammatory effects. We assessed whether statins impact circulating inflammation among Chilean women with gallstones. Materials & methods: 200 Mapuche women were matched on statin use and age to 200 non-Mapuche women in the Chile Biliary Longitudinal Study. We analyzed 92 inflammatory biomarkers using multivariable-adjusted regression models, random forests and pathway analyses. Results: Statins were not significantly associated with any inflammation marker when women were analyzed jointly or stratified by ancestry. No significant associations were found through random forest methods and pathway analyses. Discussion: We did not find significant associations between statin use and inflammation markers in women with gallstones, suggesting that statins do not reduce inflammation once gallstones have formed.

Statins are prescribed to lower cholesterol and can also decrease the risk of gallstone formation by reducing inflammation. We assessed whether statin use reduces inflammation among women who have already developed gallstones. We analyzed 92 inflammation markers among 400 women in Chile, including 200 women with Mapuche Amerindian ancestry and 200 women of Latina/European ancestry. We found that statin use was not correlated with inflammation in this group of women overall nor by ancestry. This may mean that statin use does not reduce inflammation in women who already were diagnosed with gallstones.

Optimization and Local Cost-Effectiveness of Nasopharyngeal Carcinoma Screening Strategies in Southern China: Secondary Analysis of the Guangdong Randomized Trial.

BACKGROUND: Screening with anti-Epstein-Barr virus (EBV) serology and endoscopy decreased nasopharyngeal carcinoma (NPC) mortality in Guangdong in a randomized trial. We conducted a secondary analysis of this trial using local incidence and cost data to optimize screening programs, hypothesizing that screening could be cost-effective in southern China. METHODS: Screening costs and life-years after NPC diagnosis were obtained from the Guangdong trial's intent-to-screen population (men and women aged 30-69). Seropositive subjects were rescreened annually for 5 years. Thereafter, we evaluated 12 screening strategies in Guangdong and Guangxi using a validated model. Strategies used combinations of serology, nasopharyngeal swab PCR (NP PCR), endoscopy, and MRI from trial subcohorts. Incidence data and costs were obtained from local cancer registries and the provincial healthcare system. RESULTS: In the intent-to-screen population, screening with serology and endoscopy was cost-effective (¥42,366/life-year, 0.52 GDP per capita). Screening for 5 to 15 years between ages 35 and 59 years met a willingness-to-pay threshold of 1.5 GDP/quality-adjusted life-years in all modeled populations. Despite doubling costs, adding MRI could be cost-effective via improved sensitivity. NP PCR triage reduced endoscopy/MRI referrals by 37%. One-lifetime screen could reduce NPC mortality by approximately 20%. CONCLUSIONS: EBV-based serologic screening for NPC is likely to be cost-effective in southern China. Among seropositive subjects, the preferred strategies use endoscopy alone or selective endoscopy triaged by MRI with or without NP PCR. These data may aid the design of screening programs in this region. IMPACT: These findings support population-based screening in southern China by defining the target population, cost-effectiveness, and optimized screening approach.

Association of aflatoxin with gallbladder cancer in a case-control study nested within a Chinese cohort.

We evaluated whether aflatoxin B1 (AFB1 ) exposure was associated with later risk of developing gallbladder cancer (GBC). We measured AFB1 -lysine albumin adducts in baseline samples from the Shanghai Cohort Study of 18 244 men aged 45 to 64 years (recruited 1986-1989). We included 84 GBC cases with sufficient serum and 168 controls matched on age at sample collection, date of blood draw and residence. We calculated adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) for detectable vs non-detectable AFB1 -lysine albumin adducts and gallbladder cancer. AFB1 -lysine albumin adducts were detected in 50.0% of GBC cases, and risk of GBC was twice as high in those with detectable vs undetectable levels (OR = 2.0, 95% CI = 1.0-3.9). ORs ranged from 1.8 (95% CI = 0.75-4.3) for 0.5 to <1.75 pg/mg vs undetectable adduct levels to 2.2 (95% CI = 0.91-5.6) for >3.36 pg/mg vs undetectable, suggesting a dose-response (Ptrend = .05). When restricted to cases diagnosed before the median time to diagnosis after blood draw (18.4 years), results were similar (OR = 2.2, 95% CI = 0.80-5.8) to those for the entire follow-up duration. The OR was 9.4 (95% CI = 1.7-51.1) for individuals with detectable AFB1 -lysine albumin adducts and self-reported gallstones compared to individuals with neither. Participants with detectable AFB1 -lysine albumin adducts at baseline had increased risk of developing GBC, replicating the previously observed association between AFB1 exposure and providing the first evidence of temporality.

Cohort profile: evaluation of immune response and household transmission of SARS-CoV-2 in Costa Rica: the RESPIRA study.

PURPOSE: The RESPIRA cohort aims to describe the nature, magnitude, time course and efficacy of the immune response to SARS-CoV-2 infection and vaccination, population prevalence, and household transmission of COVID-19. PARTICIPANTS: From November 2020, we selected age-stratified random samples of COVID-19 cases from Costa Rica confirmed by PCR. For each case, two population-based controls, matched on age, sex and census tract were recruited, supplemented with hospitalised cases and household contacts. Participants were interviewed and blood and saliva collected for antibodies and PCR tests. Participants will be followed for 2 years to assess antibody response and infection incidence. FINDINGS TO DATE: Recruitment included 3860 individuals: 1150 COVID-19 cases, 1999 population controls and 719 household contacts from 304 index cases. The age and regional distribution of cases was as planned, including four age strata, 30% rural and 70% urban. The control cohort had similar sex, age and regional distribution as the cases according to the study design. Among the 1999 controls recruited, 6.8% reported at enrolment having had COVID-19 and an additional 12.5% had antibodies against SARS-CoV-2. Compliance with visits and specimens has been close to 70% during the first 18 months of follow-up. During the study, national vaccination was implemented and nearly 90% of our cohort participants were vaccinated during follow-up. FUTURE PLANS: RESPIRA will enable multiple analyses, including population prevalence of infection, clinical, behavioural, immunological and genetic risk factors for SARS-CoV-2 acquisition and severity, and determinants of household transmission. We are conducting retrospective and prospective assessment of antibody levels, their determinants and their protective efficacy after infection and vaccination, the impact of long-COVID and a series of ancillary studies. Follow-up continues with bimonthly saliva collection for PCR testing and biannual blood collection for immune response analyses. Follow-up will be completed in early 2024. TRIAL REGISTRATION NUMBER: NCT04537338.

Prevalencia y determinantes de la infección por virus de papiloma humano en mujeres jóvenes de Guanacaste y Puntarenas, Costa Rica, 2004-2005.

OBJETIVO: Estimar la prevalencia e identificar determinantes de la infección por el virus del papiloma humano (VPH) en mujeres jóvenes (18-25 años). Material y métodos. Se analizaron datos de 5 871 mujeres sexualmente activas a quienes se les realizó una entrevista y toma de muestras cervicouterinas para detección de VPH y citología durante la visita de reclutamiento del Ensayo de Vacunación contra VPH16/18 en Costa Rica. Se calculó la prevalencia total para cualquier tipo de VPH y tipos oncogénicos, no oncogénicos y específicos, con intervalos de confianza al 95% (IC95%). Se utilizó regresión logística múltiple paso-a-paso para identificar determinantes asociados con la infección. RESULTADOS: La prevalencia total de VPH fue 50.0% (IC95% 48.8,51.3) y por tipos oncogénicos fue 33.8% (IC95% 32.6,35.0). El VPH-16 fue el tipo más prevalente (8.3%, IC95% 7.6,9.0). Los determinantes asociados con un alto riesgo de infección prevalente por VPH oncogénicos fueron no estar casada/unión libre, >1 compañero sexual, infección concomitante por Chlamydia trachomatis, y entre aquéllas con un único compañero sexual en su vida, un compañero con antecedente de múltiples compañeras sexuales. Conclusión. Se confirma la asociación de las infecciones por VPH oncogénicos con el comportamiento sexual de la mujer y se destacan los comportamientos del compañero sexual.

Cancers Attributable to Infections in the US in 2017: A Meta-Analysis.

Importance: Infections are largely modifiable causes of cancer. However, there remains untapped potential for preventing and treating carcinogenic infections in the US. Objective: To estimate the percentage and number of incident cancers attributable to infections in the US among adults and children for the most recent year cancer incidence data were available (2017). Data Sources: A literature search from 1946 onward was performed in MEDLINE on January 6, 2023, to obtain the data required to calculate population attributable fractions for 31 infection-cancer pairs. National Health and Nutrition Examination Survey data were used to estimate the population prevalence of hepatitis B and C viruses and Helicobacter pylori. Study Selection: Studies conducted in the US or other Western countries were selected according to specific infection-cancer criteria. Data Extraction and Synthesis: Data from 128 studies were meta-analyzed to obtain the magnitude of an infection-cancer association or prevalence of the infection within cancer cells. Main Outcomes and Measures: The proportion of cancer incidence attributable to 8 infections. Results: Of the 1 666 102 cancers diagnosed in 2017 among individuals aged 20 years or older in the US, 71 485 (4.3%; 95% CI, 3.1%-5.3%) were attributable to infections. Human papillomavirus (n = 38 230) was responsible for the most cancers, followed by H pylori (n = 10 624), hepatitis C virus (n = 9006), Epstein-Barr virus (n = 7581), hepatitis B virus (n = 2310), Merkel cell polyomavirus (n = 2000), Kaposi sarcoma-associated herpesvirus (n = 1075), and human T-cell lymphotropic virus type 1 (n = 659). Cancers with the most infection-attributable cases were cervical (human papillomavirus; n = 12 829), gastric (H pylori and Epstein-Barr virus; n = 12 565), oropharynx (human papillomavirus; n = 12 430), and hepatocellular carcinoma (hepatitis B and C viruses; n = 10 017). The burden of infection-attributable cancers as a proportion of total cancer incidence ranged from 9.6% (95% CI, 9.2%-10.0%) for women aged 20 to 34 years to 3.2% (95% CI, 2.4%-3.8%) for women aged 65 years or older and from 6.1% (95% CI, 5.2%-7.0%) for men aged 20 to 34 years to 3.3% (95% CI, 1.9%-4.4%) for men aged 65 years or older. Among those aged 19 years or younger, 2.2% (95% CI, 1.3%-3.0%) of cancers diagnosed in 2017 were attributable to Epstein-Barr virus. Conclusions and Relevance: Infections were estimated to be responsible for 4.3% of cancers diagnosed among adults in the US in 2017 and, therefore, represent an important target for cancer prevention efforts.

Estimating the cumulative incidence of SARS-CoV-2 infection in Costa Rica: modelling seroprevalence data in a population-based cohort.

Background: The true incidence of SARS-CoV-2 infection in Costa Rica was likely much higher than officially reported, because infection is often associated with mild symptoms and testing was limited by official guidelines and socio-economic factors. Methods: Using serology to define natural infection, we developed a statistical model to estimate the true cumulative incidence of SARS-CoV-2 in Costa Rica early in the pandemic. We estimated seroprevalence from 2223 blood samples collected from November 2020 to October 2021 from 1976 population-based controls from the RESPIRA study. Samples were tested for antibodies against SARS-CoV-2 nucleocapsid and the receptor-binding-domain of the spike proteins. Using a generalized linear model, we estimated the ratio of true infections to officially reported cases. Applying these ratios to officially reported totals by age, sex, and geographic area, we estimated the true number of infections in the study area, where 70% of Costa Ricans reside. We adjusted the seroprevalence estimates for antibody decay over time, estimated from 1562 blood samples from 996 PCR-confirmed COVID-19 cases. Findings: The estimated total proportion infected (ETPI) was 4.0 times higher than the officially reported total proportion infected (OTPI). By December 16th, 2021, the ETPI was 47% [42-52] while the OTPI was 12%. In children and adolescents, the ETPI was 11.0 times higher than the OTPI. Interpretation: Our findings suggest that nearly half the population had been infected by the end of 2021. By the end of 2022, it is likely that a large majority of the population had been infected. Funding: This work was sponsored and funded by the National Institute of Allergy and Infectious Diseases through the National Cancer Institute, the Science, Innovation, Technology and Telecommunications Ministry of Costa Rica, and Costa Rican Biomedical Research Agency-Fundacion INCIENSA (grant N/A).

Behavioral factors and SARS-CoV-2 transmission heterogeneity within a household cohort in Costa Rica.

INTRODUCTION: Variability in household secondary attack rates and transmission risks factors of SARS-CoV-2 remain poorly understood. METHODS: We conducted a household transmission study of SARS-CoV-2 in Costa Rica, with SARS-CoV-2 index cases selected from a larger prospective cohort study and their household contacts were enrolled. A total of 719 household contacts of 304 household index cases were enrolled from November 21, 2020, through July 31, 2021. Blood specimens were collected from contacts within 30-60 days of index case diagnosis; and serum was tested for presence of spike and nucleocapsid SARS-CoV-2 IgG antibodies. Evidence of SARS-CoV-2 prior infections among household contacts was defined based on the presence of both spike and nucleocapsid antibodies. We fitted a chain binomial model to the serologic data, to account for exogenous community infection risk and potential multi-generational transmissions within the household. RESULTS: Overall seroprevalence was 53% (95% confidence interval (CI) 48-58%) among household contacts. The estimated household secondary attack rate is 34% (95% CI 5-75%). Mask wearing by the index case is associated with the household transmission risk reduction by 67% (adjusted odds ratio = 0.33 with 95% CI: 0.09-0.75) and not sharing bedroom with the index case is associated with the risk reduction of household transmission by 78% (adjusted odds ratio = 0.22 with 95% CI 0.10-0.41). The estimated distribution of household secondary attack rates is highly heterogeneous across index cases, with 30% of index cases being the source for 80% of secondary cases. CONCLUSIONS: Modeling analysis suggests that behavioral factors are important drivers of the observed SARS-CoV-2 transmission heterogeneity within the household.

When living in the same house with known SARS-CoV-2 cases, household members may change their behavior and adopt preventive measures to reduce the spread of SARS-CoV-2. To understand how behavioral factors affect SARS-CoV-2 spreading in household settings, we focused on household members of individuals with laboratory-confirmed SARS-CoV-2 infections and followed the way SARS-CoV-2 spread within the household, by looking at who had antibodies against the virus, which means they were infected. We also asked participants detailed questions about their behavior and applied mathematical modeling to evaluate its impact on SARS-CoV-2 transmission. We found that mask-wearing by the SARS-CoV-2 cases, and avoiding sharing a bedroom with the infected individuals, reduces SARS-CoV-2 transmission. However, caring for SARS-CoV-2 cases, and prolonged interaction with infected individuals facilitate SARS-CoV-2 spreading. Our study helps inform what behaviors can help reduce SARS-CoV-2 transmission within a household.

Performance and Operational Feasibility of Epstein-Barr Virus-Based Screening for Detection of Nasopharyngeal Carcinoma: Direct Comparison of Two Alternative Approaches.

PURPOSE: Two Epstein-Barr virus (EBV)-based testing approaches have shown promise for early detection of nasopharyngeal carcinoma (NPC). Neither has been independently validated nor their performance compared. We compared their diagnostic performance in an independent population. METHODS: We tested blood samples from 819 incident Taiwanese NPC cases (213 early-stage, American Joint Committee on Cancer version 7 stages I and II) diagnosed from 2010 to 2014 and from 1,768 controls from the same region, frequency matched to cases on age and sex. We compared an EBV antibody score using immunoglobulin A antibodies measured by enzyme-linked immunosorbent assay (EBV antibody score) and plasma EBV DNA load measured by real-time PCR followed by next-generation sequencing (NGS) among EBV DNA-positive individuals (EBV DNA algorithm). RESULTS: EBV antibodies and DNA load were measured for 2,522 (802 cases; 1,720 controls) and 2,542 (797 cases; 1,745 controls) individuals, respectively. Of the 898 individuals positive for plasma EBV DNA and therefore eligible for NGS, we selected 442 (49%) for NGS testing. The EBV antibody score had a sensitivity of 88.4% (95% CI, 86.1 to 90.6) and a specificity of 94.9% (95% CI, 93.8 to 96.0) for NPC. The EBV DNA algorithm yielded significantly higher sensitivity (93.2%; 95% CI, 91.3 to 94.9; P = 1.33 × 10-4) and specificity (98.1%; 95% CI, 97.3 to 98.8; P = 3.53 × 10-7). For early-stage NPC, the sensitivities were 87.1% (95% CI, 82.7 to 92.4) for the EBV antibody score and 87.0% (95% CI, 81.9 to 91.5) for the EBV DNA algorithm (P = .514). For regions with a NPC incidence of 20-100/100,000 person-years (eg, residents in southern China and Hong Kong), these two approaches yielded similar numbers needed to screen (EBV antibody score: 5,656-1,131; EBV DNA algorithm: 5,365-1,073); positive predictive values ranged from 0.4% to 1.7% and 1.0% to 4.7%, respectively. CONCLUSION: We demonstrated high sensitivity and specificity of EBV antibody and plasma EBV DNA for NPC detection, with slightly inferior performance of the EBV antibody score. Cost-effectiveness studies are needed to guide screening implementation.

Estimating human papillomavirus vaccine efficacy from a single-arm trial: proof-of-principle in the Costa Rica Vaccine Trial.

BACKGROUND: The World Health Organization recommends a 1- or 2-dose human papillomavirus (HPV) vaccination schedule for females aged 9 to 20 years. Studies confirming the efficacy of a single dose and vaccine modifications are needed, but randomized controlled trials are costly and face logistical and ethical challenges. We propose a resource-efficient single-arm trial design that uses untargeted and unaffected HPV types as controls. METHODS: We estimated HPV vaccine efficacy (VE) from a single arm by comparing 2 ratios: the ratio of the rate of persistent incident infection with vaccine-targeted HPV 16 and 18 (HPV 16/18) and cross-protected types HPV 31, 33, and 45 (HPV 31/33/45) to vaccine-unaffected types HPV 35, 39, 51, 52, 56, 58, 59, and 66 (HPV 35/39/51/52/56/58/59/66) vs the ratio of prevalence of these types at the time of trial enrollment. We compare VE estimates using only data from the bivalent HPV 16/18 vaccine arm of the Costa Rica Vaccine Trial with published VE estimates that used both the vaccine and control arms. RESULTS: Our single-arm approach among 3727 women yielded VE estimates against persistent HPV 16/18 infections similar to published 2-arm estimates from the trial (according-to-protocol cohort: 91.0% , 95% CI = 82.9% to 95.3% [single-arm] vs 90.9% , 95% CI = 82.0% to 95.9% [2-arm]; intention-to-treat cohort: 41.7%, 95% CI = 32.4% to 49.8% [single-arm] vs 49.0% , 95% CI = 38.1% to 58.1% [2-arm]). VE estimates were also similar in analytic subgroups (number of doses received; baseline HPV serology status). CONCLUSIONS: We demonstrate that a single-arm design yields valid VE estimates with similar precision to a randomized controlled trial. Single-arm studies can reduce the sample size and costs of future HPV vaccine trials while avoiding concerns related to unvaccinated control groups. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00128661.