Laboratory-based performance evaluation of PIMA CD4+ T-lymphocyte count point-of-care by lay-counselors in Kenya

BACKGROUND

CD4+ T-lymphocyte count testing at the point-of-care (POC) may improve linkage to care of persons diagnosed with HIV-1 infection, but the accuracy of POC devices when operated by lay-counselors in the era of task-shifting is unknown. We examined the accuracy of Alere's Pima™ POC device on both capillary and venous blood when performed by lay-counselors and laboratory technicians.

METHODS

In Phase I, we compared the perfomance of POC against FACSCalibur™ for 280 venous specimens by laboratory technicians. In Phase II we compared POC performance by lay-counselors versus laboratory technicians using 147 paired capillary and venous specimens, and compared these to FACSCalibur™. Statistical analyses included Bland-Altman analyses, concordance correlation coefficient, sensitivity, and specificity at treatment eligibility thresholds of 200, 350, and 500cells/μl.

RESULTS

Phase I: POC sensitivity and specificity were 93.0% and 84.1% at 500cells/μl, respectively. Phase II: Good agreement was observed for venous POC results from both lay-counselors (concordance correlation coefficient (CCC)=0.873, bias -86.4cells/μl) and laboratory technicians (CCC=0.920, bias -65.7cells/μl). Capillary POC had good correlation: lay-counselors (CCC=0.902, bias -71.2cells/μl), laboratory technicians (CCC=0.918, bias -63.0cells/μl). Misclassification at the 500 cells/μl threshold for venous blood was 13.6% and 10.2% for lay-counselors and laboratory technicians and 12.2% for capillary blood in both groups. POC tended to under-classify the CD4 values with increasingly negative bias at higher CD4 values.

CONCLUSIONS

Pima™ results were comparable to FACSCalibur™ for both venous and capillary specimens when operated by lay-counselors. POC CD4 testing has the potential to improve linkage to HIV care without burdening laboratory technicians in resource-limited settings.

Adventitious agents and live viral vectored vaccines: Considerations for archiving samples of biological materials for retrospective analysis

Vaccines are one of the most effective public health medicinal products with an excellent safety record. As vaccines are produced using biological materials, there is a need to safeguard against potential contamination with adventitious agents. Adventitious agents could be inadvertently introduced into a vaccine through starting materials used for production. Therefore, extensive testing has been recommended at specific stages of vaccine manufacture to demonstrate the absence of adventitious agents. Additionally, the incorporation of viral clearance steps in the manufacturing process can aid in reducing the risk of adventitious agent contamination. However, for live viral vaccines, aside from possible purification of the virus or vector, extensive adventitious agent clearance may not be feasible. In the event that an adventitious agent is detected in a vaccine, it is important to determine its origin, evaluate its potential for human infection and pathology, and discern which batches of vaccine may have been affected in order to take risk mitigation action. To achieve this, it is necessary to have archived samples of the vaccine and ancillary components, ideally from developmental through to current batches, as well as samples of the biological materials used in the manufacture of the vaccine, since these are the most likely sources of an adventitious agent. The need for formal guidance on such vaccine sample archiving has been recognized but not fulfilled. We summarize in this paper several prior major cases of vaccine contamination with adventitious agents and provide points for consideration on sample archiving of live recombinant viral vector vaccines for use in humans.

Live virus vaccines based on a vesicular stomatitis virus (VSV) backbone: Standardized template with key considerations for a risk/benefit assessment

The Brighton Collaboration Viral Vector Vaccines Safety Working Group (V3SWG) was formed to evaluate the safety of live, recombinant viral vaccines incorporating genes from heterologous viral and other microbial pathogens in their genome (so-called "chimeric virus vaccines"). Many such viral vector vaccines are now at various stages of clinical evaluation. Here, we introduce an attenuated form of recombinant vesicular stomatitis virus (rVSV) as a potential chimeric virus vaccine for HIV-1, with implications for use as a vaccine vector for other pathogens. The rVSV/HIV-1 vaccine vector was attenuated by combining two major genome modifications. These modifications acted synergistically to greatly enhance vector attenuation and the resulting rVSV vector demonstrated safety in sensitive mouse and non-human primate neurovirulence models. This vector expressing HIV-1 gag protein has completed evaluation in two Phase I clinical trials. In one trial the rVSV/HIV-1 vector was administered in a homologous two-dose regimen, and in a second trial with pDNA in a heterologous prime boost regimen. No serious adverse events were reported nor was vector detected in blood, urine or saliva post vaccination in either trial. Gag specific immune responses were induced in both trials with highest frequency T cell responses detected in the prime boost regimen. The rVSV/HIV-1 vector also demonstrated safety in an ongoing Phase I trial in HIV-1 positive participants. Additionally, clinical trial material has been produced with the rVSV vector expressing HIV-1 env, and Phase I clinical evaluation will initiate in the beginning of 2016. In this paper, we use a standardized template describing key characteristics of the novel rVSV vaccine vectors, in comparison to wild type VSV. The template facilitates scientific discourse among key stakeholders by increasing transparency and comparability of information. The Brighton Collaboration V3SWG template may also be useful as a guide to the evaluation of other recombinant viral vector vaccines.

Vaccination and unexplained sudden death risk in Taiwanese infants

PURPOSE

In March 1992, eight infants who had died within 36 hours of receiving whole-cell pertussis vaccine (diphtheria, tetanus, and whole-cell pertussis [DTwP]) prompted the Taiwan health authorities to suspend its use. We conducted an investigation of vaccination and sudden unexplained infant death (SUID) and repeated it more recently after Taiwan switched to acellular pertussis vaccine (diphtheria, tetanus, and acellular pertussis [DTaP]) in 2010.

METHODS

All SUIDs aged 31-364 days during 1990-1992 and 1996-2013 were selected from the death registration databases. The case-control investigation matched each case to two controls on clinic, sex, and birth date, whereas the follow-up self-controlled case series study compared risk of death during the 30-day post-vaccination risk periods with those in the control periods within the same case.

RESULTS

Sudden unexplained infant death was associated with never receiving DTwP (odds ratio 2.28, 95% confidence interval 1.25-4.15) in the case-control investigation. The odds ratios within 0-1, 2-7, 8-14, and 15-30 days of DTwP administration were 1.18, 0.26, 0.50, and 0.77. In the 1996-2013 self-controlled case series studies, this temporal shift between DTwP and SUID was consistently observed for female (incidence rate ratio 1.70, 0.75, 1.01, and 0.84) but not male or DTaP recipients. A pooled analysis showed significant risk within 2 days of receiving DTwP in female infants (incidence rate ratio 1.66, 95% confidence interval 1.05-2.60).

CONCLUSIONS

Being unvaccinated and recent receipt of DTwP in female infants was significantly associated with SUID; the latter was consistent with a temporal shift pattern without overall increase in risk. The currently used pertussis vaccine, DTaP, did not increase risk of SUID. Copyright © 2016 John Wiley & Sons, Ltd.

Contributions and challenges for worldwide vaccine safety: The Global Advisory Committee on Vaccine Safety at 15 years

In 1999, the Global Advisory Committee on Vaccine Safety (GACVS) was established by the World Health Organization (WHO) to provide independent scientific advice on issues relating to the safety of vaccines and immunization. Fifteen years onward, we conducted a multi-faceted review to evaluate the impact, reach and challenges facing GACVS, including the role GACVS plays in informing global, regional and WHO member state vaccine policy. The methods included measures of organizational structure, citation impact, themes approached, and a discussion by previous and current members to evaluate past, present and future challenges. Given the increasing range of data sources and the deployment of many new vaccines, the Committee is facing the complex task of identifying the best available evidence for recommendations on vaccine safety. To help meet the increased demand for public transparency in decision making, GACVS-structured methodology for evidence-based decisions is evolving. GACVS also promotes best practices and capacity building for timely and accurate risk assessment; risk communications; outreach to help countries maintain and, if needed, rebuild public trust in vaccines; and advocacy for bridging the major gaps in vaccine safety capacity globally.

Enhancing Vaccine Safety Capacity Globally: A Lifecycle Perspective

Major vaccine safety controversies have arisen in several countries beginning in the last decades of 20th century. Such periodic vaccine safety controversies are unlikely to go away in the near future as more national immunization programs mature with near elimination of target vaccine-preventable diseases that result in relative greater prominence of adverse events following immunizations, both true reactions and temporally coincidental events. There are several ways in which vaccine safety capacity can be improved to potentially mitigate the impact of future vaccine safety controversies. This paper aims to take a "lifecycle" approach, examining some potential pre- and post-licensure opportunities to improve vaccine safety, in both developed (specifically U.S. and Europe) and low- and middle-income countries.

Enhancing vaccine safety capacity globally: A lifecycle perspective

Major vaccine safety controversies have arisen in several countries beginning in the last decades of 20th century. Such periodic vaccine safety controversies are unlikely to go away in the near future as more national immunization programs mature with near elimination of target vaccine-preventable diseases that result in relative greater prominence of adverse events following immunizations, both true reactions and temporally coincidental events. There are several ways in which vaccine safety capacity can be improved to potentially mitigate the impact of future vaccine safety controversies. This paper aims to take a "lifecycle" approach, examining some potential pre- and post-licensure opportunities to improve vaccine safety, in both developed (specifically U.S. and Europe) and low- and middle-income countries.

Live virus vaccines based on a yellow fever vaccine backbone: standardized template with key considerations for a risk/benefit assessment

The Brighton Collaboration Viral Vector Vaccines Safety Working Group (V3SWG) was formed to evaluate the safety of live, recombinant viral vaccines incorporating genes from heterologous viruses inserted into the backbone of another virus (so-called "chimeric virus vaccines"). Many viral vector vaccines are in advanced clinical trials. The first such vaccine to be approved for marketing (to date in Australia, Thailand, Malaysia, and the Philippines) is a vaccine against the flavivirus, Japanese encephalitis (JE), which employs a licensed vaccine (yellow fever 17D) as a vector. In this vaccine, two envelope proteins (prM-E) of YF 17D virus were exchanged for the corresponding genes of JE virus, with additional attenuating mutations incorporated into the JE gene inserts. Similar vaccines have been constructed by inserting prM-E genes of dengue and West Nile into YF 17D virus and are in late stage clinical studies. The dengue vaccine is, however, more complex in that it requires a mixture of four live vectors each expressing one of the four dengue serotypes. This vaccine has been evaluated in multiple clinical trials. No significant safety concerns have been found. The Phase 3 trials met their endpoints in terms of overall reduction of confirmed dengue fever, and, most importantly a significant reduction in severe dengue and hospitalization due to dengue. However, based on results that have been published so far, efficacy in preventing serotype 2 infection is less than that for the other three serotypes. In the development of these chimeric vaccines, an important series of comparative studies of safety and efficacy were made using the parental YF 17D vaccine virus as a benchmark. In this paper, we use a standardized template describing the key characteristics of the novel flavivirus vaccine vectors, in comparison to the parental YF 17D vaccine. The template facilitates scientific discourse among key stakeholders by increasing the transparency and comparability of information. The Brighton Collaboration V3SWG template may also be useful as a guide to the evaluation of other recombinant viral vector vaccines.

Correlates of prevalent HIV infection among adults and adolescents in the Kisumu incidence cohort study, Kisumu, Kenya

We estimated HIV prevalence and identified correlates of HIV infection among 1106 men and women aged 16-34 years residing in Kisumu, Kenya. Demographic, sexual, and other behavioural data were collected using audio computer-assisted self-interview in conjunction with a medical examination, real-time parallel rapid HIV testing, and laboratory testing for pregnancy, gonorrhoea, chlamydia, syphilis, and herpes simplex virus type 2. Multivariate logistic regression was used to identify variables associated with prevalent HIV infection by gender. Overall HIV prevalence was 12.1%. HIV prevalence among women (17.1%) was approximately two-and-one-half times the prevalence among men (6.6%). Odds of HIV infection in men increased with age (aOR associated with one-year increase in age = 1.21, CI = 1.07-1.35) and were greater among those who were uncircumcised (aOR = 4.42, CI = 1.41-13.89) and those who had an herpes simplex virus type 2-positive (aOR = 3.13, CI = 1.12-8.73) test result. Odds of prevalent HIV infection among women also increased with age (aOR associated with one-year increase in age = 1.16, CI = 1.04-1.29). Women who tested herpes simplex virus type 2 positive had more than three times the odds (aOR = 3.85, CI = 1.38-10.46) of prevalent HIV infection compared with those who tested herpes simplex virus type 2 negative. Tailored sexual health interventions and programs may help mitigate HIV age and gender disparities.

The Brighton Collaboration Viral Vector Vaccines Safety Working Group (V3SWG)

Recombinant viral vectors provide an effective means for heterologous antigen expression in vivo and thus represent promising platforms for developing novel vaccines against human pathogens from Ebola to tuberculosis. An increasing number of candidate viral vector vaccines are entering human clinical trials. The Brighton Collaboration Viral Vector Vaccines Safety Working Group (V3SWG) was formed to improve our ability to anticipate potential safety issues and meaningfully assess or interpret safety data, thereby facilitating greater public acceptance when licensed.

Rates of adverse events associated with male circumcision in U.S. medical settings, 2001 to 2010

IMPORTANCE

Approximately 1.4 million male circumcisions (MCs) are performed annually in US medical settings. However, population-based estimates of MC-associated adverse events (AEs) are lacking.

OBJECTIVES

To estimate the incidence rate of MC-associated AEs and to assess whether AE rates differed by age at circumcision.

DESIGN

We selected 41 possible MC AEs based on a literature review and on medical billing codes. We estimated a likely risk window for the incidence calculation for each MC AE based on pathogenesis. We used 2001 to 2010 data from SDI Health, a large administrative claims data set, to conduct a retrospective cohort study.

SETTING AND PARTICIPANTS

SDI Health provided administrative claims data from inpatient and outpatient US medical settings.

MAIN OUTCOMES AND MEASURES

For each AE, we calculated the incidence per million MCs. We compared the incidence risk ratio and the incidence rate difference for circumcised vs uncircumcised newborn males and for males circumcised at younger than 1 year, age 1 to 9 years, or 10 years or older. An AE was considered probably related to MC if the incidence risk ratio significantly exceeded 1 at P < .05 or occurred only in circumcised males.

RESULTS

Records were available for 1,400,920 circumcised males, 93.3% as newborns. Of 41 possible MC AEs, 16 (39.0%) were probable. The incidence of total MC AEs was slightly less than 0.5%. Rates of potentially serious MC AEs ranged from 0.76 (95% CI, 0.10-5.43) per million MCs for stricture of male genital organs to 703.23 (95% CI, 659.22-750.18) per million MCs for repair of incomplete circumcision. Compared with boys circumcised at younger than 1 year, the incidences of probable AEs were approximately 20-fold and 10-fold greater for males circumcised at age 1 to 9 years and at 10 years or older, respectively.

CONCLUSIONS AND RELEVANCE

Male circumcision had a low incidence of AEs overall, especially if the procedure was performed during the first year of life, but rose 10-fold to 20-fold when performed after infancy.

Medical risks and benefits of newborn male circumcision in the United States: physician perspectives

INTRODUCTION

In 2012, the American Academy of Pediatrics (AAP) and the American Congress of Obstetricians and Gynecologists (ACOG) published recommendations that physicians should discuss with parents the benefits and risks of newborn male circumcision. Our objective was to assess physicians' perspectives of newborn male circumcision.

METHODS

A self-administered, cross-sectional electronic survey of US physicians was conducted in 2008 (N = 1500).

RESULTS

Approximately one-third (33.2%) of the respondents reported that their current perspective was that the medical benefits outweigh the risks associated with newborn male circumcision and less than one-third (31.1%) reported they would recommend the procedure when counseling parents.

CONCLUSIONS

In 2008, only about one-third of the physicians surveyed thought that the benefits of male circumcision outweighed the risks and recommended it to parents of newborn sons. These attitudes may be relevant to the declining circumcision rates in the United States. Repeat surveys may be useful, given the new AAP and ACOG recommendations.

Evaluation of syndromic management of sexually transmitted infections within the Kisumu Incidence Cohort Study

While laboratory aetiological diagnosis is considered the gold standard for diagnosis and management of sexually transmitted infections (STIs), syndromic management has been presented as a simplified and affordable approach for STI management in limited resource settings. STI signs and symptoms were collected using staff-administered computer-assisted personal interview and audio computer-assisted self-interview. Participants underwent a medical examination and laboratory testing for common STIs. The performance of syndromic management was assessed on the agreement between interviewing methods as well as accurate diagnosis. We screened 846 participants, of whom 88 (10.4%) received syndromic STI diagnosis while 272 (32.2%) received an aetiological diagnosis. Agreement between syndromic and aetiological diagnoses was very poor (overall kappa = 0.09). The most prevalent STI was herpes simplex virus type 2 and the percentage of persons with any STI was higher among women (48.6%) than men (15.6%, p < 0.0001). Agreement between audio computer-assisted self-interview and computer-assisted personal interview interviewing methods for syndromic diagnosis of STIs ranged from poor to good. Our findings suggest that syndromic management of STIs is not a sufficient tool for STI diagnosis in this setting; development and improvement of STI diagnostic capabilities through laboratory confirmation is needed in resource-limited settings.

Men who have sex with men in Kisumu, Kenya: comfort in accessing health services and willingness to participate in HIV prevention studies

Men who have sex with men (MSM) are a crucial and marginalized at risk population for HIV in Africa but are poorly studied. Like other areas of Africa, homosexuality is illegal in Kenya. We assessed MSM comfort in accessing health services and willingness to participate in HIV prevention research in Kisumu, Kenya-an area of high HIV prevalence. We conducted a two-phase formative study with individual interviews (n = 15) and a structured survey (n = 51). Peer contact or snowball method (n = 43, 84.3%) was the primary recruitment strategy used to locate MSM. Exact logistic regression models were used for survey data analysis. Over 60% (32/51) of survey participants were not very comfortable seeking health services from a public hospital. Almost all MSM (49/51; 96.1%) reported willingness to be contacted to participate in future HIV research studies. Efforts to provide facilities that offer safe and confidential health services and health education for MSM is required. Continued community engagement with the MSM population in Kenya is needed to guide best practices for involving them in HIV prevention research.

Investigation of HIV Incidence Rates in a High-Risk, High-Prevalence Kenyan Population: Potential Lessons for Intervention Trials and Programmatic Strategies

Cost-effective HIV prevention programs should target persons at high risk of HIV acquisition. We conducted an observational HIV incidence cohort study in Kisumu, Kenya, where HIV prevalence is triple that of the national rate. We used referral and venue-sampling approaches to enroll HIV-negative persons for a 12-month observational cohort, August 2010 to September 2011, collected data using computer-assisted interviews, and performed HIV testing quarterly. Among 1292 eligible persons, 648 (50%) were excluded for HIV positivity and other reasons. Of the 644 enrollees, 52% were women who were significantly older than men (P<.01). In all, 7 persons seroconverted (incidence rate [IR] per 100 person-years=1.11; 95% confidence interval [CI] 0.45-2.30), 6 were women; 5 (IR=3.14; 95% CI 1.02-7.34) of whom were ≤25 years. Most new infections occurred in young women, an observation consistent with other findings in sub-Saharan Africa that women aged ≤25 years are an important population for HIV intervention trials in Africa.

Template protocol for clinical trials investigating vaccines--focus on safety elements

This document is intended as a guide to the protocol development for trials of prophylactic vaccines. The template may serve phases I-IV clinical trials protocol development to include safety relevant information as required by the regulatory authorities and as deemed useful by the investigators. This document may also be helpful for future site strengthening efforts.

Correlates of health attitudes among homosexual and bisexual men

There is increased emphasis on physician attention to the overall health and wellness of homosexual and bisexual men, though little is known about the health-related attitudes of these groups. This study determined factors associated with the health attitudes of homosexual and bisexual men and identified preferred sources of health information. For this study, the 2008 ConsumerStyles panel survey was used to create three health attitude scales and to determine factors associated with each scale. The three scales were labeled: (1) health motivation; (2) relationship with health care provider; and (3) self-perception of health literacy. In addition to other factors, higher scores for health motivation and relationship with health care provider were associated with black compared with white men. In contrast, lower scores for self-perception of health literacy were associated with black compared with white men. For information on an unfamiliar health condition, most homosexual and bisexual men chose the Internet. Black homosexual and bisexual men reported being motivated to be healthy and working well with their health care provider to manage their health. However, their perception of their own health motivation was low compared with the white men. Attempts to improve health literacy through Internet sites may be helpful in improving health attitudes and reducing negative health outcomes.

Baseline findings of an HIV incidence cohort study to prepare for future HIV prevention clinical trials in Kisumu, Kenya

Introduction

In an analysis of baseline findings of an HIV incidence cohort study, an assessment was made of HIV prevalence among persons presenting for enrollment and any differences in demographic characteristics between persons not enrolled compared to those enrolled. We also described and compared HIV risk behaviors in males and females enrolled in the study.

Methodology

A computer-assisted survey was administered to collect baseline demographic and HIV risk data from 1,277 men and women aged 18–34 years. Testing for HIV and other sexually transmitted infections (STI) was conducted. Out of 1,277 persons prescreened for eligibility, 625 were enrolled.

Results

HIV prevalence of all persons who completed screening was 14.8% (females: 21.1%; males: 8.1%). The odds of being enrolled in the study were higher for persons 18–24 years compared to those 30–34 years of age [adjusted odds ratio (AOR)=2.18, CI=1.13, 4.21] and males compared to females [AOR=2.07, CI=1.43, 2.99]. Among those enrolled in the study, the most prevalent HIV risk behaviors were unprotected sex (49%), alcohol use (45%), and transactional sex (30%) in the last three months. Compared to females, a significantly greater proportion of males reported using any alcohol or recreational drug in the last three months, a history of oral sex, sex with partner other than a spouse or main partner, ever having a blood transfusion, ever being treated for an STI, and having knowledge of their last HIV test result.

Conclusion

The Kisumu Field Station successfully recruited individuals with HIV risk characteristics for the HIV incidence cohort study.

Investigation of an outbreak of hypersensitivity-type reactions during the 2004 national measles-mumps-rubella vaccination campaign in Brazil

INTRODUCTION

During Brazil's national measles, mumps, and rubella (MMR) vaccination campaign in August 2004, an unexpectedly high rate of hypersensitivity-type adverse events (HAEs) was reported.

MATERIALS AND METHODS

We reviewed information about children with suspected HAEs reported by clinicians to Brazil's national passive surveillance system for adverse events following immunization (AEFI), compared attack rate of HAE by manufacturer of MMR vaccine used in the campaign, and conducted a case-control study to determine possible risk factors for HAEs.

RESULTS

During the 2004 national campaign, the rate of HAEs following MMR vaccination was one log higher for manufacturer A (15.2/100,000 doses administered) compared to the other two manufacturers (1.2 and 0.6/100,000 doses; p<0.0001); a similar pattern was observed retrospectively in analysis of the 2000-2003 AEFI surveillance (0.95 vs. 0.07 per 100,000 doses administered; p<0.0001). In the case-control study, among the 49 case-patients with HAEs identified, reported symptoms included conjunctival injection (60%), urticaria (55%), fever (54%), and facial edema (53%); no deaths occurred. The median time interval between vaccination and symptom onset was 42min (range: 5min-24h). We did not identify any differences in the proportion of case-patients and control children with a history of known allergy to food (including egg, egg-containing products or gelatin), drugs, or environmental antigens.

DISCUSSION

Our study highlights the importance of a well-functioning routine AEFI surveillance system linked with mass vaccination campaigns. Such a system in Brazil permitted timely detection of HAEs and validation of a safety signal associated with one vaccine manufacturer. Unlike earlier publications, this outbreak linked to a single manufacturer of MMR showed no association with a prior allergic history to eggs or other foods, including gelatin; subsequent studies implicate the dextran stabilizer in MMR from manufacturer A as the likely cause of HAEs.

Need for physician education on the benefits and risks of male circumcision in the United States

Physicians may be called upon to counsel male patients or parents of newborn males regarding their decision to circumcise their newborn sons. The purpose of the present study was to describe physicians who do not understand the benefits and risks associated with male circumcision well enough to counsel parents of newborn male infants and adult men. A self-administered, cross-sectional electronic survey of physicians was conducted in 2008. We analyzed responses from 1,500 physicians (510 family practitioners, 490 internists, 250 pediatricians, and 250 obstetricians/gynecologists). Nearly 22% (n = 327/1500) reported they did not understand the risks and benefits of newborn male circumcision well enough to counsel parents and 40.3% (n = 504/1250) reported not understanding the risks and benefits well enough to counsel adult men. A substantial minority of physicians may need additional training and/or information about current male circumcision research to feel comfortable counseling parents of newborn male infants or adult men.

Ultracompact and fabrication-tolerant integrated polarization splitter

Design and fabrication of a 2×2 two-mode interference (TMI) coupler based on-chip polarization splitter is presented. By changing the angle between the access waveguides, one can tune the effective TMI length for the mode with less optical confinement (transverse magnetic, TM) to coincide with the target TMI length for a desired transmission of the mode with higher optical confinement (transverse electric, TE). The fabricated 0.94 μm long 2×2 TMI splits the input power into TM (bar) and TE (cross) outputs with splitting ratio over 15 dB over 50 nm bandwidth. Fabrication tolerance analysis shows that the device is tolerant to fabrication errors as large as 60 nm.