H2 inhalation therapy in patients with moderate COVID-19 (H2COVID): a prospective ascending-dose phase I clinical trial.

The coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has triggered a serious global health crisis, resulting in millions of reported deaths since its initial identification in China in November 2019. The global disparities in immunization access emphasize the urgent need for ongoing research into therapeutic interventions. This study focuses on the potential use of molecular dihydrogen (H2) inhalation as an adjunctive treatment for COVID-19. H2 therapy shows promise in inhibiting intracellular signaling pathways associated with inflammation, particularly when administered early in conjunction with nasal oxygen therapy. This phase I study, characterized by an open-label, prospective, monocentric, and single ascending-dose design, seeks to assess the safety and tolerability of the procedure in individuals with confirmed SARS-CoV-2 infection. Employing a 3 + 3 design, the study includes three exposure durations (target durations): 1 day (D1), 3 days (D2), and 6 days (D3). We concluded that the maximum tolerated duration is at least 3 days. Every patient showed clinical improvement and excellent tolerance to H2 therapy. To the best of our knowledge, this phase I clinical trial is the first to establish the safety of inhaling a mixture of H2 (3.6%) and N2 (96.4%) in hospitalized COVID-19 patients. The original device and method employed ensure the absence of explosion risk. The encouraging outcomes observed in the 12 patients included in the study justify further exploration through larger, controlled clinical trials. CLINICAL TRIALS: This study is registered with ClinicalTrials.gov as NCT04633980.

Surgical rhinoplasty after prior hyaluronic acid based nose remodeling.

BACKGROUND: Medical rhinoplasty by hyaluronic acid injection (HA) has become nowadays a common practice. The number of patients requesting surgical rhinoplasty and having already undergone one or more injections of HA is increasing. However, the literature lacks publications regarding the management of these patients. OBJECTIVES: The aim of this study is to discuss the management of patients who have been treated with previous nasal HA injections and who seek surgical rhinoplasty, and elaborate a treatment protocol and algorithm to standardize surgical plans. METHODS: We are reporting case studies based on our clinical experience. We also reviewed the literature to suggest perioperative management for rhinoplasty with previous HA injections. RESULTS: Hyaluronidase injection preoperatively allows to carry out an accurate preoperative analysis of the nasal deformities to treat, in order to make an adapted treatment plan. Postoperative course is similar to other rhinoplasty cases without the use of this enzyme. CONCLUSION: Hyaluronidase should be used in all patients with nasal injections of HA (unless contraindications), who are willing to undergo a surgical rhinoplasty. The operation can be undertaken at one-week interval as soon as the edema subsides and no further treatments are necessary.

Scrotal reconstruction after Fournier's Gangrene using the superficial circumflex iliac artery perforator (SCIP) propeller flap: A case report.

INTRODUCTION: Fournier's gangrene, a rare infectious condition affecting the external genitalia, often requires aggressive medical-surgical interventions, resulting in variable scrotal tissue loss. Despite numerous proposed reconstruction techniques, achieving a consensus on the most effective approach that balances aesthetics and function remains elusive. This case report presents a one-year follow-up on scrotal reconstruction using a pedicled Superficial Circumflex Iliac Artery Perforator (SCIP) propeller flap. CASE REPORT: A 56-year-old patient with significant scrotal tissue loss due to Fournier's gangrene underwent scrotal reconstruction using a pedicled SCIP propeller flap. Optimal placement was ensured through a subcutaneous tunnel, with a thin thigh skin graft applied to cover the penile skin defect. DISCUSSION: The SCIP flap is distinguished by its thin and pliable characteristics, rapid harvesting and featuring a discreet donor site. It stands as a compelling alternative to skin grafts, providing advantages in sensory restoration, color congruence, and resilience against tension. Considering the thickness of the reconstruction helps both in recovering testicular function and improving the appearance by restoring the natural contour. CONCLUSION: The utilization of the pedicled SCIP propeller flap for scrotal tissue loss resulting from Fournier's gangrene has demonstrated both aesthetic and functional success, underscoring its potential as an effective reconstructive option.

[Vulvoplasty after gender-affirmating genital surgery]. / Vulvoplastie chez les patientes en incongruence de genre.

Functional and aesthetic results after vaginoplasty in sexual reassignment surgery have improved in recent years. Improved surgical techniques, well-established expert teams and a growing demand for and interest in this type of surgery are some of the reasons for these results. However, there is a growing demand for genital cosmetic surgery, not only among cis women, but also among trans women. The main shortcomings in results are therefore presented and listed. The aesthetic revision surgery techniques specifically indicated are described. Labiaplasty and clitoridoplasty appear to be the two main requests for secondary surgery following trans vaginoplasty.

[Scapular flap, an alternative to the radial forearm flap in phalloplasty: Advantages and limitations]. / Lambeau scapulaire, une alternative au lambeau antébrachial en phallopoièse : avantages et inconvénients.

INTRODUCTION: Antebrachial phalloplasty is considered as the standard technique in total penile reconstruction. This technique allows the creation of a phallus and a neourethra in one step at the cost of significant sequelae of the donor site. Thus, this technique has been replaced in some centers by other techniques such as the MSLD flap or the ALT flap. However, in Western populations, these techniques require the addition of a technique dedicated to the urethroplasty. The scapular flap is a technique that is not widely described in the literature and, like the antebrachial flap, allows the creation of a phallus and a urethra in one step according to the "tube within tube" technique. AIM: The aim of the study was to detail this technique, to study its vascularization and to adapt the measurements of the flap to a western population. PATIENTS AND METHODS: Six cadaveric dissections were performed in the laboratory. Intravascular injection of colored latex allowed easier identification of the vessels of interest and study of the subcutaneous vascular tree. Scapular flaps of variable size were raised to adapt the size to a Western population. RESULTS: Six dissections were performed in Caucasian subjects. The scapular circumflex artery was constant and had a mean diameter of 3.5mm (3.3mm-3.8mm). The mean pedicle length was 7.3cm (6.8cm-8.1cm). The size of the flaps was adapted to the subcutaneous tissue and flaps of at least 14×16cm allowed the "tube within tube" technique to be performed. CONCLUSION: The scapular flap has the advantage of allowing phalloplasty with urethroplasty to be performed at the same time. The pedicle is constant and of good diameter. In addition, the sequelae of the donor site are minimal. On the other hand, the pedicle used is short and the flap cannot be surgically reinnervated. Nevertheless, the restoration of a protective sensitivity allows the implantation of a penile prosthesis.

The bilateral scrotal flap: Anatomical study and it's use for the management of inflammatory granulomas following custom-made injections.

INTRODUCTION: The management of 10 cases of penile inflammatory granulomas following a subcutaneous injection of non-absorbable substance for the purpose of penile augmentation is presented. We subsequently used the bilateral scrotal flaps to cover the post-excision skin defect. A simple decision aid chart outlining the management of penile foreign body injections is proposed. METHODS: A total of 10 patients were included in this study. All required surgical management by penile degloving, followed by complete excision of the inflammatory granuloma and overlying skin. The dissection of 14 cadavers was carried out to study the blood supply to the anterior scrotal flap. Penile reconstruction was then performed using a bilateral scrotal flap in all but two cases. Post-operatively, the patients were followed up for a 1 year period. RESULTS: We obtained good results in terms of the aesthetic outcome with all of our ten patients with the area covered having similar color to penile skin. There were no major post-operative complications. There were two minor complications involving wound healing. Sensory function was maintained and no penile shortening or curvatures were noted, in addition all patients were satisfied with both the shape and function of the penis. CONCLUSION: Although much rarer, penile augmentation related complications are still seen in western countries. The treating doctor should be aware of its management. We had achieved acceptable outcomes in our experience with the bilateral scrotal flap. We believe it is a good and simple option for soft tissue coverage of the penis in cases following the complete inflammatory granuloma excision. It can achieve satisfactory aesthetic and functional results for this group of patients.

[Profunda femoral artery perforator flap: Anatomical study]. / Le lambeau perforant de l'artère fémorale profonde : une étude anatomique morphométrique.

BACKGROUND: Within the framework of mammary reconstruction, since 2012 when Allen first described it, the profunda femoral artery perforator flap (PAP) takes an important place in the current therapeutic options. OBJECTIVE: This anatomical study aims to analyze the anatomy and morphologic consideration of the PAP : position of the perforating artery; length of the pedicle, area and volume of vascularization. METHODS: Sixteen flaps were harvested on fresh subjects at the University Department of Anatomy of Rockfeller, Lyon. The first direct cutaneous branch from the deep femoral vessels was located between or through the adductor magnus and gracilis muscles. Pedicle location, diameter, length and position regard to the great saphenous vein were recorded. A flap based on this vessel was designed. Height, width, and surface of the skin paddle were recorded. Three-dimensional computed tomographic angiography was used to analyze the area and volume of cutaneous territory supplied by the studied perforator. RESULTS: On the 16 analyzed flaps, localization of the perforating artery is on average to 8.2cm of the pubic tuber and 3.7cm behind a line connecting the pubic tuber to the internal femoral condyle. The length of the pedicle is on average of 11.7cm and the average area of skin perfused was 94,68cm2. The way of this perforating arterty is primarily through the adductor magnus. On the radiological images of the 8 flaps, the analysis shows an average surface of 111,25cm2 and a mean volume of 325.3cm3. DISCUSSION: PAP is an interesting therapeutic choice within the framework of a mammary reconstruction. Its surface and its volume associated with a discrete scar make a valid indication within the framework of this surgery.

An anatomic study of deep inferior epigastric artery diameters at the origin from external iliac and at the lateral border of rectus abdominis muscle by computed tomographic angiography from autologous breast reconstruction patients.

BACKGROUND: Autologous breast reconstruction by means of microsurgical abdominal flaps is an very well described technique. The flap harvest dissection under inguinal ligament would cause the risk of parietal weakening in this zone and postoperative bulging. The goal of our study is to investigate whether the deep inferior epigastric artery diameter remains constant from its exit of the external iliac artery to its entrance in the rectus muscle sheath. PATIENTS AND METHOD: One hundred arteries were studied on fifty preoperative computed tomographic angiographies made before a DIEAP flap for breast reconstruction. We measured the caliber of the left and right deep inferior epigastric arteries at these two landmarks. The length of this artery between these was also calculated. This data were collected with specific angiography reconstruction. RESULTS: At the caudal landmark, the mean DIEA diameter was 2.1±0.27mm on the left side and 2.1±0.31mm on the right side. At the cephalic landmark, the mean DIEA diameter was 2.0±0.28mm on the left and 2.0±0.27mm on the right side (P=0.00035 at left side; P=0.0089 at right side). The mean pedicle length between the two landmarks was 22.3±2.85mm on the left side and 22.2±2.98mm on the right side. CONCLUSION: This computed tomographic angiography study showed that the diameter of DIEA is equivalent at its origin and at the lateral border of muscle. Flap harvest without dissection under inguinal ligament provides sufficient pedicle length and caliber to allow for comfortable and reliable sutures.

Impact of East Coast fever on Grande Comore: assessment taking a participatory epidemiology approach.

East Coast fever (ECF), one of the most serious tick-borne diseases in sub-Saharan and eastern Africa, was introduced to the island of Grande Comore in 2002 through zebu import from Tanzania, resulting in at least a 10% loss of livestock. A participatory epidemiology initiative was launched in 2015 to gain a better understanding of ECF epidemiology. Thirty-six villages were investigated involving 36 focus group sessions and 120 individual questionnaires. Farmers' knowledge of ECF and of priority diseases affecting the country was assessed, and the impacts of ECF and other major diseases were compared by a scoring method. The results showed that 69.4% (95% CI [51.3, 87.5%]) of the farmers had good to very good knowledge of ECF. The most important cattle diseases on Grande Comore were considered to be East Coast fever, heartwater, babesiosis, and cutaneous diseases. About 58% of the farmers (95% CI [49.2, 66.8%]) use curative treatments when cattle were sick. Between January and September 2015, the ECF incidence was estimated at 18.5% (95% CI [15.5, 21.4%]), and 87.5% (95% CI [72.7, 100%]) of the cattle infected by ECF died. The ECF incidence estimated in our study was found to be less when compared to that observed in Tanzania even though the climatic conditions in the Union of the Comoros are suitable for the biological vector of ECF, the tick species Rhipicephalus appendiculatus. Access to chemical treatment and its effectiveness against ECF, as well as controlling borders and organizing quarantine, are discussed.

[French adaptation of a new score for global assessment of psoriasis severity: The Simplified Psoriasis Index (SPI)]. / Adaptation française d'un nouveau score destiné à l'évaluation globale de la sévérité du psoriasis : l'Indice Simplifié du Psoriasis (Simplified Psoriasis Index, SPI).

OBJECTIVE: Although several scores exist to assess psoriasis severity, most have marked limitations that rule out their use in routine clinical practice. A new score, the Simplified Psoriasis Index (SPI), has recently been developed and validated in adults in Britain for such use. It has separate components for current severity (SPI-s), psychosocial impact (SPI-p) and past history and interventions (SPI-p), and it is suitable for either professional assessment or patient self-assessment. The aim of this work was to produce a validated translation of SPI into French (as spoken in France). METHODS: The index was translated and validated using a strict methodology comprising respectively five and eight phases for the professional (proSPI) and self-administered instruments (saSPI). Translation of the saSPI instrument also involved a cognitive debriefing with five psoriasis patients. RESULTS: Linguistic discrepancies and subtle differences of meaning arising during the process were closely examined. The developer of the instrument ensured conceptual accuracy. A panel of health experts guaranteed that medical terms were correctly translated. Five patients with plaque psoriasis (two female and three male of median age 45 years [range: 31-78]) tested the SPI-p version during cognitive interviews and found the questionnaire clear and easy to understand. CONCLUSION: Validated French translations of both SPI instruments are now available for use in routine clinical practice. Further investigations are currently underway to validate the psychometric properties of the instrument.

[Breast reconstruction with Muscle-Sparing Latissimus Dorsi flap combined to a Thoraco-Abdominal advancement flap and fat grafting]. / Reconstruction mammaire par lambeau dorsal épargnant le muscle grand dorsal (Muscle-Sparing Latissimus Dorsi, MSLD) associé à un lambeau d'avancement thoraco-abdominal et greffe de tissu adipeux autologue.

The Latissimus Dorsi flap (or LD flap) was first described by the Tansini in 1896 and published in 1906. It concerned a case of chest wall reconstruction after breast amputation. The use of the LD flap in all its variants is very frequent in breast reconstruction. In these indications, the muscle is harvested for skin paddle vascularization and/or for bringing volume to the reconstructed breast. When all or most of the muscle is taken, its motor function is completely lost. The functional sequelae due to the loss of the latissimus dorsi muscle are then definitive. Tobin et al. showed that the LD muscle can be separated into two flaps based on the division of the thoracodorsal artery; the concept of muscle-sparing was then posed (Muscle-Sparing Latissimus Dorsi [MSLD]). The MSLD as we perform now, concerns only a thin muscle strip and preserves 95% of the LD muscle with its vascularization and motor innervation. This technique is quick with very low donor site morbidity. The functional sequelae and postoperative complications appear limited compared to the harvest of a total LD whatever the posterior scar. The volume of the breast to be reconstructed is obtained by several sessions of fat grafting. We present here the anatomical bases and the surgical technique of the muscle-sparing latissimus dorsi associated with a thoracoabdominal advancement flap and fat grafting in breast reconstruction.

[Fasciocutaneous flap reliable by deep femoral artery perforator for the treatment of ischial pressure ulcers]. / Lambeau fasciocutané sous fessier fiabilisé par une perforante de l'artère fémorale profonde en reconstruction d'escarre ischiatique.

INTRODUCTION: The surgical management of pressure ulcers in the paraplegic or quadriplegic population is marked by the high risk of recurrence in the long-term. In the current era of perforator flaps, newer reconstructive options are available for the management of pressure ulcers, decreasing the need to use the classically described muscular or musculocutaneous locoregional flaps. The coverage of ischial sores described in this article by a pedicled flap based on a deep femoral artery perforator, appears to be an effective first-line reconstructive option for the management of limited size pressure ulcers. PATIENTS AND METHOD: A number of fifteen paraplegic or quadriplegic patients having at least one ischial bed sore with underlying osteomyelitis were included in this series. The approximate location of the deep femoral artery perforator was initially identified using the "The Atlas of the perforator arteries of the skin, the trunk and limbs", which was confirmed, with the use of a Doppler device. A fasciocutaneous transposition flap was elevated, with the pivot point based on the cutaneous bridge centered on the perforator, and then transposed to cover the area of tissue loss. The donor site was closed primarily. RESULTS: A total of fifteen patients were operated from November 2015 to November 2016. The series comprised of 16 first presentations of a stage 4 pressure ulcers associated with underlying osteomyelitis that were subsequently reconstructed by the pedicled deep femoral artery perforator flap. The healing rate and functional results were both satisfactory. CONCLUSION: Fasciocutaneous flap reliable by deep femoral artery perforator appears to have a promising role in the treatment of ischial pressure sores. It is an attractive option to spare the use of musculocutaneous flaps in the area. Thus this flap could be used as a first-line option to cover ischial pressure ulcers of limited size.

Hospitalisation for lower respiratory tract infection in children in the province of Quebec, Canada, before and during the pneumococcal conjugate vaccine era.

Streptococcus pneumoniae is an important cause of community-acquired pneumonia and pneumococcal conjugate vaccines (PCVs) may reduce this burden. This study's goal was to analyse trends in lower respiratory tract infections (LRTI) hospitalisations before and during a routine vaccination programme targeting all newborns with PCV was started in the province of Quebec, Canada in December 2004. The study population included hospital admissions with a main diagnosis of LRTI among 6-59 month-old Quebec residents from April 2000 to December 2014. Trends in proportions and rates were analysed using Cochran-Armitage tests and Poisson regression models. We observed a general downward trend in all LTRI hospitalisations rate: from 11·55/1000 person-years in 2000-2001 to 9·59/1000 in 2013-2014, a 17·0% reduction, which started before the introduction of PCV vaccination. Downward trends in hospitalisation rates were more pronounced for all-cause of pneumonia (minus 17·8%) than for bronchiolitis (minus 15·4%). There was also a decrease in the mean duration of hospital stay. There was little evidence that all-cause pneumonia decreased over the study period due mainly to the introduction of PCVs. Trends may be related to changes in clinical practice. This study casts doubt on the interpretation of ecological analyses of the implementation of PCV vaccination programmes.

Anatomy and Aesthetics of the Labia Minora: The Ideal Vulva?

Female genital cosmetic surgery is becoming more and more widespread both in the field of plastic and gynaecological surgery. The increased demand for vulvar surgery is spurred by the belief that the vulva is abnormal in appearance. What is normal in terms of labial anatomy? Labia minora enlargement or hypertrophy remains a clinical diagnosis which is poorly defined as it could be considered a variation of the normal anatomy. Enlarged labia minora can cause functional, aesthetic and psychosocial problems. In reality, given the wide variety of vulvar morphology among people, it is a very subjective issue to define the "normal" vulva. The spread of nudity in the general media plays a major role in creating an artificial image and standards with regard to the ideal form. Physicians should be aware that the patient's self-perception of the normal or ideal vulva is highly influenced by the arguably distorted image related to our socio-psychological environment, as presented to us by the general media and internet. As physicians, we have to educate our patients on the variation of vulvar anatomy and the potential risks of these surgeries. Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these evidence-based medicine ratings, please refer to Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Nipple reconstruction using rib cartilage strut in microsurgical reconstructed breast.

Nipple areolar reconstruction is the very last step of breast reconstruction. It is of outmost importance because it gives final appearance of breast, which is then better integreated by the patient in her body image. A lot of techniques are described to recreate nipple projection, from trompe l'œil tattoo to local flap, nipple sharing or autologous tissue graft. Common drawback of these techniques is nipple flattening with time, due to tissue atrophy. We present here a technique to use rib cartilage graft as structural framework for nipple reconstruction. Rib cartilage is stored in a pocked created in the groin during first step of breast microsurgical reconstruction. During nipple-areolar reconstruction, graft is cut at appropriate size and used inside a C-V flap to enhance nipple projection. Results show excellent symmetry and projection and is stable over time. Patients are very satisfied and can better integrate their new breast.

[Incisions and baseline operative technique of cervicofacial lifting]. / Incisions et technique opératoire de base du lifting cervicofacial.

Cervicofacial lifting is one of the most iconic procedure of plastic surgery and is about hundred years old. In the following chapters of this report, numerous technical points will be specify. A baseline reliable and reproducible technique, appealing to the largest possible audience is presented in order to begin this surgery in optimum conditions. Pre- and postoperative management is also exposed. The aim of this chapter is to precise incisions and baseline operative technique of cervicofacial lifting, with description of SMAS and platysma suspensions as well as complementary procedures like liposuccion and lipofilling. This chapter will lay the foundation of more complex elements that will be described in the various following chapters.

[Facial feminization surgery - middle and inferior thirds]. / Chirurgie de féminisation du visage ­ tiers moyen et inférieur.

The authors present the surgical techniques of facial feminization of the middle third and the inferior third in the context of sexual reassignment surgery. These techniques adapted to patients 'male to female' are proposed to strong masculine facial features of patients and are based in the middle third of the remodeling of the malar region by fat grafting, reduction and/or deprojection techniques in rhinoseptoplasty and upper lip surgery. Concerning the inferior third, remodeling of the mandibular angles, genioplasty and chondrolaryngoplasty are adapted.

[Phalloplasty: Microsurgical options and management algorithm]. / Phalloplastie : options microchirurgicales et algorithme décisionnel.

The free radial forearm flap is considered as the gold standard in penile reconstruction for good functional and aesthetic results. The scar on donor site could be considered as pathognomonic of their situation by transsexual patients. The development of microsurgical flaps provides new therapeutic options. This options are discussed and a therapeutic algorithm is presented. The main techniques used are the pedicled anterolateral thigh perforator flap and free muscle sparing latissimus dorsi flap. Principal criteria are listed, the choice of patient and the local anatomical conditions are the most important. Antebrachial flap stay the first choice. In case of non-feasibility of this flap, phalloplasty with pedicle ALT flap or free MSLD flap will be proposed. Urethral reconstruction will be done by a narrow free forearm flap or by a delayed thin skin graft or buccal mucosa graft. Microsurgical phalloplasty options are not limited to the forearm flap. Satisfactory results can be obtained using alternative procedure. The use of a therapeutic algorithm allows to choose the most optimal solution for each patient.

Sequence capture using RAD probes clarifies phylogenetic relationships and species boundaries in Primula sect. Auricula.

Species-rich evolutionary radiations are a common feature of mountain floras worldwide. However, the frequent lack of phylogenetic resolution in species-rich alpine plant groups hampers progress towards clarifying the causes of diversification in mountains. In this study, we use the largest plant group endemic to the European Alpine system, Primula sect. Auricula, as a model system. We employ a newly developed next-generation-sequencing protocol, involving sequence capture with RAD probes, and map reads to the reference genome of Primula veris to obtain DNA matrices with thousands of SNPs. We use these data-rich matrices to infer phylogenetic relationships in Primula sect. Auricula and examine species delimitations in two taxonomically difficult subgroups: the clades formed by the close relatives of P. auricula and P. pedemontana, respectively. Our molecular dataset enables us to resolve most phylogenetic relationships in the group with strong support, and in particular to infer four well-supported clades within sect. Auricula. Our results support existing species delimitations for P. auricula, P. lutea, and P. subpyrenaica, while they suggest that the group formed by P. pedemontana and close relatives might need taxonomic revision. Finally, we discuss preliminary implications of these findings on the biogeographic history of Primula sect. Auricula.

Predictors of hospitalization for lower respiratory tract infection in children aged <2 years in the province of Quebec, Canada.

Young age, adverse environmental conditions and infectious agents are established risk factors of lower respiratory tract infection (LRTI), whereas pneumococcal conjugate vaccines may be protective. To explore their relative role as predictors of hospitalizations under the continental climate prevailing in the province of Quebec, Canada, an ecological study was performed. Records with a main diagnosis of LRTI in children born during 2007-2010 and observed up to their second-year anniversary were extracted from the provincial hospital administrative database. Respiratory virus surveillance data and statistics on ambient air temperature were obtained. Vaccine use in different birth cohorts was derived from the Quebec City Immunization Registry. Additive and multiplicative Poisson regression models were applied to estimate attributable fractions. Age, month of birth, ambient temperature, and respiratory syncytial virus (RSV), human metapneumovirus (hMPV) and influenza-positive test proportions were significant predictors of LRTI hospitalizations. No substantial differences were observed in cohorts exposed to the 7-valent or 10-valent pneumococcal conjugate vaccines. In the additive model, the fraction of hospitalizations explained by temperature variation was 37%, whereas RSV circulation explained 28%, hMPV 4% and influenza 1%. Complex interplay between biological, environmental and social mechanisms may explain the important role of ambient air temperature in predicting LRTI hospitalization risk in young children.