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A key unsolved question in the current coronavirus disease 2019 (COVID-19) pandemic is the duration of acquired immunity. Insights from infections with the four seasonal human coronaviruses might reveal common characteristics applicable to all human coronaviruses. We monitored healthy individuals for more than 35 years and determined that reinfection with the same seasonal coronavirus occurred frequently at 12 months after infection. The durability of immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unknown. Lessons from seasonal coronavirus infections in humans show that reinfections can occur within 12 months of initial infection, coupled with changes in levels of virus-specific antibodies.

Background HIV self-testing (HIVST) has been found to be highly effective, but no cost analysis has been undertaken to guide the design of affordable and scalable implementation strategies. Methods Consecutive HIV self-testers and facility-based testers were recruited from participants in a community cluster-randomised trial ( ISRCTN02004005 ) investigating the impact of offering HIVST in addition to facility-based HIV testing and counselling (HTC). Primary costing studies were undertaken of the HIVST service and of health facilities providing HTC to the trial population. Costs were adjusted to 2014 US$ and INT$. Recruited participants were asked about direct non-medical and indirect costs associated with accessing either modality of HIV testing, and additionally their health-related quality of life was measured using the EuroQol EQ-5D. Results A total of 1,241 participants underwent either HIVST (n = 775) or facility-based HTC (n = 446). The mean societal cost per participant tested through HIVST (US$9.23; 95 % CI: US$9.14-US$9.32) was lower than through facility-based HTC (US$11.84; 95 % CI: US$10.81-12.86). Although the mean health provider cost per participant tested through HIVST (US$8.78) was comparable to facility-based HTC (range: US$7.53-US$10.57), the associated mean direct non-medical and indirect cost was lower (US$2.93; 95 % CI: US$1.90-US$3.96). The mean health provider cost per HIV positive participant identified through HIVST was higher (US$97.50) than for health facilities (range: US$25.18-US$76.14), as was the mean cost per HIV positive individual assessed for anti-retroviral treatment (ART) eligibility and the mean cost per HIV positive individual initiated onto ART. In comparison to the facility-testing group, the adjusted mean EQ-5D utility score was 0.046 (95 % CI: 0.022-0.070) higher in the HIVST group. Conclusions HIVST reduces the economic burden on clients, but is a costlier strategy for the health provider aiming to identify HIV positive individuals for treatment. The provider cost of HIVST could be substantially lower under less restrictive distribution models, or if costs of oral fluid HIV test kits become comparable to finger-prick kits used in health facilities.

HIV self-testing (HIVST) may play a role in addressing gaps in HIV testing coverage and as an entry point for HIV prevention services. We conducted a cluster randomized trial of 2 HIVST distribution mechanisms compared to the standard of care among female sex workers (FSWs) in Zambia. Trained peer educators in Kapiri Mposhi, Chirundu, and Livingstone, Zambia, each recruited 6 FSW participants. Peer educator-FSW groups were randomized to 1 of 3 arms: (1) delivery (direct distribution of an oral HIVST from the peer educator), (2) coupon (a coupon for collection of an oral HIVST from a health clinic/pharmacy), or (3) standard-of-care HIV testing. Participants in the 2 HIVST arms received 2 kits: 1 at baseline and 1 at 10 weeks. The primary outcome was any self-reported HIV testing in the past month at the 1- and 4-month visits, as HIVST can replace other types of HIV testing. Secondary outcomes included linkage to care, HIVST use in the HIVST arms, and adverse events. Participants completed questionnaires at 1 and 4 months following peer educator interventions. In all, 965 participants were enrolled between September 16 and October 12, 2016 (delivery, N = 316; coupon, N = 329; standard of care, N = 320); 20% had never tested for HIV. Overall HIV testing at 1 month was 94.9% in the delivery arm, 84.4% in the coupon arm, and 88.5% in the standard-of-care arm (delivery versus standard of care risk ratio [RR] = 1.07, 95% CI 0.99-1.15, P = 0.10; coupon versus standard of care RR = 0.95, 95% CI 0.86-1.05, P = 0.29; delivery versus coupon RR = 1.13, 95% CI 1.04-1.22, P = 0.005). Four-month rates were 84.1% for the delivery arm, 79.8% for the coupon arm, and 75.1% for the standard-of-care arm (delivery versus standard of care RR = 1.11, 95% CI 0.98-1.27, P = 0.11; coupon versus standard of care RR = 1.06, 95% CI 0.92-1.22, P = 0.42; delivery versus coupon RR = 1.05, 95% CI 0.94-1.18, P = 0.40). At 1 month, the majority of HIV tests were self-tests (88.4%). HIV self-test use was higher in the delivery arm compared to the coupon arm (RR = 1.14, 95% CI 1.05-1.23, P = 0.001) at 1 month, but there was no difference at 4 months. Among participants reporting a positive HIV test at 1 (N = 144) and 4 months (N = 235), linkage to care was non-significantly lower in the 2 HIVST arms compared to the standard-of-care arm. There were 4 instances of intimate partner violence related to study participation, 3 of which were related to HIV self-test use. Limitations include the self-reported nature of study outcomes and overall high uptake of HIV testing. In this study among FSWs in Zambia, we found that HIVST was acceptable and accessible. However, HIVST may not substantially increase HIV cascade progression in contexts where overall testing and linkage are already high. ClinicalTrials.gov NCT02827240.

Hepatitis Delta Virus (HDV), a satellite virus of Hepatitis B virus, exacerbates liver damage in affected individuals. Screening for HDV antibodies in HBsAg positive patients is recommended, but the diagnostic accuracy of serological tests remains uncertain. This review aimed to assess the diagnostic accuracy of serological tests for HDV. We searched PubMed, Web of Science, Cochrane Central Register of Controlled Trials, Scopus etc. for relevant studies. Studies measuring the sensitivity and specificity of serological HDV tests against PCR as a reference standard were included. Pooled sensitivity and specificity for each test method and sero-marker were calculated. The review included six studies with 11 study arms, evaluating ARCHITECT immunoassay, EIA, ELISA, QMAC, RIA, and Western Blot test methods targeting Anti-HDV IgG, Total anti-HDV and Anti-HDV IgM. Sensitivities for Anti-HDV IgG, Total Anti-HDV and Anti-HDV IgM, tests were 97.4%, 51.9%, and 62.0%, respectively, with specificities of 95.3%, 80.0%, and 85.0%. Our findings, with its limited number of studies, suggest that HDV serological tests, particularly those identifying Anti IgG exhibit high accuracy and can serve as effective screening tools for HDV.

Background Prevention of new HIV infections is a critical public health issue. The highest HIV testing gaps are in men, adolescents 15–19 years old, and adults 40 years and older. Community-based HIV testing services (HTS) can contribute to increased testing coverage and early HIV diagnosis, with HIV self-testing (HIVST) strategies showing promise. Community-based strategies, however, are resource intensive, costly and not widely implemented. A community-led approach to health interventions involves supporting communities to plan and implement solutions to improve their health. This trial aims to determine if community-led delivery of HIVST can improve HIV testing uptake, ART initiation, and broader social outcomes in rural Malawi. Methods The trial uses a parallel arm, cluster-randomised design with group village heads (GVH) and their defined catchment areas randomised (1:1) to community-led HIVST or continue with the standard of the care (SOC). As part of the intervention, informal community health cadres are supported to plan and implement a seven-day HIVST campaign linked to HIV treatment and prevention. Approximately 12 months after the initial campaign, intervention GVHs are randomised to lead a repeat HIVST campaign. The primary outcome includes the proportion of adolescents 15–19 years old who have tested for HIV in their lifetime. Secondary outcomes include recent testing in adults 40 years and older and men; ART initiation; knowledge of HIV prevention; and HIV testing stigma. Outcomes will be measured through cross-sectional surveys and clinic registers. Economic evaluation will determine the cost per person tested, cost per person diagnosed, and incremental cost effectiveness ratio. Discussion To the best of our knowledge, this is the first trial to assess the effectiveness of community-led HTS, which has only recently been enabled by the introduction of HIVST. Community-led delivery of HIVST is a promising new strategy for providing periodic HIV testing to support HIV prevention in rural communities. Further, introduction of HIVST through a community-led framework seems particularly apt, with control over healthcare concurrently devolved to individuals and communities. Trial registration Clinicaltrials.gov registry ( NCT03541382 ) registered 30 May 2018.

The cause of Lyme disease, Borrelia burgdorferi, was discovered in 1983. A 2-tiered testing protocol was established for serodiagnosis in 1994, involving an enzyme immunoassay (EIA) or indirect fluorescence antibody, followed (if reactive) by immunoglobulin M and immunoglobulin G Western immunoblots. These assays were prepared from whole-cell cultured B. burgdorferi, lacking key in vivo expressed antigens and expressing antigens that can bind non-Borrelia antibodies. Additional drawbacks, particular to the Western immunoblot component, include low sensitivity in early infection, technical complexity, and subjective interpretation when scored by visual examination. Nevertheless, 2-tiered testing with immunoblotting remains the benchmark for evaluation of new methods or approaches. Next-generation serologic assays, prepared with recombinant proteins or synthetic peptides, and alternative testing protocols, can now overcome or circumvent many of these past drawbacks. This article describes next-generation serodiagnostic testing for Lyme disease, focusing on methods that are currently available or near-at-hand.

Requirements for documentation of measles (Me) immunity in health care workers (HCWs) vary. At the University of Otago, New Zealand (NZ), student HCWs with or without two documented doses of Me-mumps (Mu) -rubella (Ru) (MMR) vaccine, are tested for Me, Mu, and Ru IgG by an indirect sandwich chemiluminescent immunoassay (CLIA) and receive a third dose of MMR (MMR3) if seronegative for Me, Mu, or Ru. We compared Me seropositivity by CLIA with two tests at the Netherlands Public Health Institute (RIVM): in-house bead-based multiplex immunoassay (MIA) and plaque reduction neutralization test (PRNT), using Me seropositivity thresholds of ≥16.5 Arbitrary Units (AU)/ml for CLIA and ≥ 0.12 International Units (IU)/ml for MIA and PRNT. Of 725 students, 175 (24.1 %) were below CLIA thresholds for ≥1 of Me, Mu, or Ru, and received MMR, with 88 (50.2 %) participating in the study. Seropositivity for Me by CLIA was significantly less common (43; 48.9 %; 95 % CI: 38.5, 59.4) than for MIA (80, 90.9 %; 95 % CI: 82.7, 95.4) or PRNT (74; 84.1 % (95 % CI, 74.8, 90.4). Among the 14 PRNT seronegatives, proportions of false positives by CLIA (4/43, 9.3 %) and MIA (7/80, 8.8 %) were similar. Among PRNT seropositives, the only MIA seronegative was in low positive (<0.24 IU/ml) range, whereas among CLIA seronegatives, 26/55 (47.2 %) had PRNT >0.24 IU/ml. Our finding that CLIA did not detect neutralizing antibody in a high proportion of vaccinated young adults agrees with other studies. In our study population, approximately 9 % of Me seropositives on both MIA and CLIA had PRNT <0.12 IU/ml. In elimination settings, non-PRNT serological tests have significant limitations in two-dose vaccinated HCWs, with implications for their use in screening to determine requirement for MMR3.

We used commercially available ELISAs to test 68 samples from coronavirus disease cases and prepandemic controls from Benin. We noted <25% false-positive results among controls, likely due to unspecific immune responses elicited by acute malaria. Serologic tests must be carefully evaluated to assess coronavirus disease spread and immunity in tropical regions.

A major gap in the Plasmodium vivax elimination toolkit is the identification of individuals carrying clinically silent and undetectable liver-stage parasites, called hypnozoites. This study developed a panel of serological exposure markers capable of classifying individuals with recent P. vivax infections who have a high likelihood of harboring hypnozoites. We measured IgG antibody responses to 342 P. vivax proteins in longitudinal clinical cohorts conducted in Thailand and Brazil and identified candidate serological markers of exposure. Candidate markers were validated using samples from year-long observational cohorts conducted in Thailand, Brazil and the Solomon Islands and antibody responses to eight P. vivax proteins classified P. vivax infections in the previous 9 months with 80% sensitivity and specificity. Mathematical models demonstrate that a serological testing and treatment strategy could reduce P. vivax prevalence by 59–69%. These eight antibody responses can serve as a biomarker, identifying individuals who should be targeted with anti-hypnozoite therapy. Plasmodium vivax can cause a clinically silent liver-stage infection that can reactivate, triggering blood-stage disease. A new test measuring antibody responses can identify P. vivax carriers for targeted treatment intervention.

The case fatality rate of rabies, nearly 100%, is one of the most unique characteristic of this ancient virus infection. The crucial role rabies virus neutralizing antibody plays in protection is both well established and explanation of why rabies serology is important. Various laboratory methods can and have been used but serum neutralization methods have long been the gold standard due to the ability to measure function (neutralization), however these methods can be difficult to perform for several reasons. Assays such as enzyme linked absorbance assays (ELISA), indirect fluorescence antibody (IFA) and more recently lateral flow methods are in use. Interpretation of results can be problematic, not only between methods but also due to modifications of the same method that can lead to misinterpretations. A common assumption in review of laboratory test results is that different methods for the same component produce comparable results under all conditions or circumstances. Assumptions and misinterpretations provide the potential for detrimental decisions, ranging from regulatory to clinically related, and most importantly what ‘level’ is protective. Review of the common challenges in performance and interpretation of rabies serology and specific examples illuminate critical issues to consider when reviewing and applying results of rabies serological testing.