This week in Infectious Disease

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Welcome to This Week in Infectious Disease. This week we're covering 10 notable papers spanning vaccine effectiveness and prevention across very different settings, global diagnostics and elimination programmes for tuberculosis and schistosomiasis, and a cluster of studies on managing serious infections in complex hosts. Let's dive in.

We'll start with prevention, where three papers converge on how well vaccines actually perform outside trial conditions. In Clinical Infectious Diseases, Lewis and colleagues report test-negative vaccine effectiveness data from a multistate surveillance network of 26 medical centres in the United States during the 2024 to 2025 influenza season, a season marked by sustained high activity and some antigenically drifted H3N2 viruses. Among adults hospitalised with acute respiratory illness, vaccination was associated with about a 40 percent reduction in influenza-associated hospitalisation, consistent across age groups and influenza A subtypes. What is more striking is the gradient with severity: protection against invasive organ support and against intensive care admission was on the order of 58 percent, and against in-hospital death roughly half, though that death estimate was the least precise. This is observational and test-negative in design, with the residual confounding that entails, but it is consistent with prior seasons and supports the argument that even a moderately matched vaccine blunts the severe end of the spectrum. [1] Also in Clinical Infectious Diseases, Berhe and colleagues address a long-standing gap in Africa with a multi-centre observational study in Ethiopia of 387 infants born to hepatitis B surface antigen positive, HIV-negative mothers. Overall mother-to-child transmission was about 5 percent. Among infants who got no immunoprophylaxis at birth and relied on the routine schedule starting at six weeks, transmission was roughly 15 percent; among the 39 infants who received a timely birth dose alone, there were no transmissions, and among the 217 who received birth dose plus hepatitis B immune globulin, also none. High maternal viral load and e-antigen positivity sharply raised risk in unprotected infants. The birth-dose groups are small, so the upper bound of true risk is not zero, but the authors conclude that a six-week start is insufficient and that timely birth-dose vaccination should be prioritised for scale-up. [3] Rounding out prevention, Open Forum Infectious Diseases carries a systematic review and meta-analysis by Pereira and colleagues of the M72 AS01 tuberculosis vaccine in people living with HIV, pooling three randomised trials and 510 participants. Reactogenicity was clearly higher, with roughly three-fold more injection-site pain and about double the rate of fever, headache and myalgia, but events were predominantly mild to moderate and self-limited, with no increase in unsolicited adverse events and no vaccine-related serious adverse events. Certainty was high for common events and low for rare severe ones. This is a safety signal, not an efficacy signal, in virologically suppressed adults on antiretroviral therapy, and the authors frame it as justification for efficacy trials in this population rather than evidence of benefit. [7]

The second theme is global programme science, where two Lancet Global Health papers ask how to do more with constrained resources. Garg and colleagues report a prospective diagnostic accuracy study of pooled sputum testing on Xpert Ultra across seven countries and more than 14,000 participants, with culture as the reference standard. Pooling specimens, mostly in groups of four, gave sensitivity about three percentage points lower than individual testing, at roughly 85 percent, with marginally better specificity, and it halved cartridge consumption. The important caveat is where pooling fails: agreement with individual testing stayed above 96 percent for high, medium and low semiquantitative grades, but fell to about 87 percent for very low and only around 55 percent for trace results. So the paucibacillary patient is the one most likely to be missed, which matters in high-HIV settings, and the authors position this for low to moderate positivity settings where access, not sensitivity at the margin, is the binding constraint. [5] The companion elimination story comes from Leta and colleagues, who surveyed more than 121,000 Ethiopian children aged 9 to 14 at over 4,000 sites and built one-kilometre resolution geostatistical prevalence maps. After a decade of preventive chemotherapy, combined schistosome prevalence was about 5 percent, and the population living in areas above the threshold for annual mass treatment fell from roughly 25.6 million to 10.8 million. Heavy-intensity infection was 0.2 percent, below the World Health Organization's one percent target for elimination as a public health problem. Just 11 percent of assessed subdistricts still require annual preventive chemotherapy. This is cross-sectional and relies on Kato-Katz, which underperforms at low intensity, but it is the kind of fine-grained map that lets a national programme stop treating everywhere and start treating somewhere. [10]

The third theme is the management of serious infection in complicated hosts, and here the findings are more heterogeneous. In Open Forum Infectious Diseases, Vena and colleagues retrospectively reviewed 639 episodes of Pseudomonas aeruginosa bloodstream infection across 14 Italian hospitals. Thirty-day all-cause mortality overall was about 24 percent. Source control was judged necessary in about a third of episodes, and was achieved early and adequately in roughly half of those. Mortality in that early adequate source control group was about 6 percent, against about 24 percent when source control was needed but not achieved early. A propensity-matched analysis retained a large protective association. This is retrospective and vulnerable to the obvious confounder that patients well enough to undergo a drainage or line removal are patients who survive, but the signal is strong and reinforces source control as a determinant of outcome alongside appropriate antibiotics. [2] Also in Clinical Infectious Diseases, Mendu and colleagues report a target trial emulation in Botswana using a case-cohort design among more than 14,000 adults, with over a thousand incident anogenital cancers. Compared with adults without HIV, cancer risk did not fall with longer antiretroviral therapy. It was highest in those treated ten years or more, and the relative risks for the rarer sites were extreme, particularly penile and vulvar cancer. Prior advanced HIV disease contributed relatively little. The authors are careful that this reflects survival into the age of cancer risk as much as anything, but the message is that long-term viral suppression alone is not a cancer prevention strategy in this population, and human papillomavirus-directed prevention and screening remain the gap. [4] Two shorter but practical papers close this theme. In the International Journal of Antimicrobial Agents, Guo and colleagues developed and validated a four-variable model, using age, tigecycline daily dose, total bilirubin and baseline fibrinogen at treatment initiation, to predict fibrinogen deterioration. Discrimination was moderate, with an area under the curve around 0.75 in development and falling to roughly 0.69 in the full prospective cohort, with calibration drift; the authors explicitly state local recalibration should precede any threshold-based use, and that the model stratifies monitoring intensity rather than treatment choice. [8] And in Clinical Infectious Diseases, McCrary and colleagues measured glecaprevir and pibrentasvir in the breastmilk of lactating women on hepatitis C treatment, finding concentrations well under 5 percent of maternal plasma and relative infant doses of well under a tenth of one percent. It is a small pharmacokinetic study without infant outcome data, but it is reassuring exposure data where essentially none existed. [9] Finally, a conceptual piece in Clinical Infectious Diseases from Li and Modlin examines the ethics of Candida auris screening in solid organ transplantation, noting that no national or professional guidelines in the United States specify who, how or when to screen, and arguing for risk-based rather than universal screening as a defensible middle ground while data mature. [6]

If you only have time for one paper this week, make it the Ethiopian hepatitis B birth dose study in Clinical Infectious Diseases [3]. It supplies the African effectiveness data that has been missing from a long-running policy debate, and it directly challenges the adequacy of vaccination schedules that begin at six weeks.

Here is what this week's evidence adds up to in Infectious Disease. First, in a drifted influenza season, vaccination in adults in the United States was still associated with meaningful protection, and the protection was largest against the most severe outcomes, though these are observational estimates. Second, timing matters more than completeness in hepatitis B prophylaxis: no transmissions occurred among birth-dose recipients in the Ethiopian cohort, but the birth-dose groups were small and the finding is observational. Third, pooled molecular testing for tuberculosis buys roughly half the cartridges for a small sensitivity cost, concentrated almost entirely in trace-positive, paucibacillary disease, which defines where it can and cannot be deployed. Fourth, in Pseudomonas bacteraemia, early adequate source control was associated with markedly lower mortality, and while confounding by indication cannot be excluded in a retrospective cohort, the effect size is hard to ignore. And fifth, a decade of antiretroviral therapy did not reduce anogenital cancer risk in Botswana, leaving human papillomavirus prevention as the unaddressed problem for people ageing with HIV.

That's your roundup for This Week in Infectious Disease. The full transcript and references are available on the episode page in your AudioScholar library. This is an AI-curated summary — for clinical decisions, always consult primary sources and current guidelines. See you next week.

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This is an automated summary generated by artificial intelligence, which can make mistakes. Always review the original source materials.