Humoral and Cellular Immune Response Elicited by the BNT162b2 COVID-19 Vaccine Booster in Elderly.

Although the safety and efficacy of COVID-19 vaccines in older people are critical to their success, little is known about their immunogenicity among elderly residents of long-term care facilities (LTCFs). A single-center prospective cohort study was conducted: a total IgG antibody titer, neutralizing antibodies against Wild-type, Delta Plus, and Omicron BA.2 variants and T cell response, were measured eight months after the second dose of BNT162b2 vaccine (T0) and at least 15 days after the booster (T1). Forty-nine LTCF residents, with a median age of 84.8 ± 10.6 years, were enrolled. Previous COVID-19 infection was documented in 42.9% of the subjects one year before T0. At T1, the IgG titers increased up to 10-fold. This ratio was lower in the subjects with previous COVID-19 infection. At T1, IgG levels were similar in both groups. The neutralizing activity against Omicron BA.2 was significantly lower (65%) than that measured against Wild-type and Delta Plus (90%). A significant increase of T cell-specific immune response was observed after the booster. Frailty, older age, sex, cognitive impairment, and comorbidities did not affect antibody titers or T cell response. In the elderly sample analyzed, the BNT162b2 mRNA COVID-19 vaccine produced immunogenicity regardless of frailty.

Multicellular Liver Organoids: Generation and Importance of Diverse Specialized Cellular Components.

Over 40,000 patients in the United States are estimated to suffer from end-stage liver disease and acute hepatic failure, for which liver transplantation is the only available therapy. Human primary hepatocytes (HPH) have not been employed as a therapeutic tool due to the difficulty in growing and expanding them in vitro, their sensitivity to cold temperatures, and tendency to dedifferentiate following two-dimensional culture. The differentiation of human-induced pluripotent stem cells (hiPSCs) into liver organoids (LO) has emerged as a potential alternative to orthotropic liver transplantation (OLT). However, several factors limit the efficiency of liver differentiation from hiPSCs, including a low proportion of differentiated cells capable of reaching a mature phenotype, the poor reproducibility of existing differentiation protocols, and insufficient long-term viability in vitro and in vivo. This review will analyze various methodologies being developed to improve hepatic differentiation from hiPSCs into liver organoids, paying particular attention to the use of endothelial cells as supportive cells for their further maturation. Here, we demonstrate why differentiated liver organoids can be used as a research tool for drug testing and disease modeling, or employed as a bridge for liver transplantation following liver failure.

Mucosal immune response after the booster dose of the BNT162b2 COVID-19 vaccine.

BACKGROUND: To date, only a few studies reported data regarding the development of mucosal immune response after the BNT162b2-booster vaccination. METHODS: Samples of both serum and saliva of 50 healthcare workers were collected at the day of the booster dose (T3) and after two weeks (T4). Anti-S1-protein IgG and IgA antibody titres and the neutralizing antibodies against the Wuhan wild-type Receptor-Binding Domain in both serum and saliva were measured by quantitative and competitive ELISA, respectively. Data were compared with those recorded after the primary vaccination cycle (T2). Neutralizing antibodies against the variants of concern were measured in those individuals with anti-Wuhan neutralizing antibodies in their saliva. FINDINGS: After eight months from the second dose, IgG decreased in both serum (T2GMC: 23,838.5 ng/ml; T3GMC: 1473.8 ng/ml) and saliva (T2GMC: 12.9 ng/ml; T3GMC: 0.3 ng/ml). Consistently, serum IgA decreased (T2GMC: 48.6 ng/ml; T3GMC: 6.4 ng/ml); however, salivary IgA showed a different behaviour and increased (T2GMC: 0.06 ng/ml; T3GMC: 0.41 ng/ml), indicating a delayed activation of mucosal immunity. The booster elicited higher titres of both IgG and IgA when compared with the primary cycle, in both serum (IgG T4GMC: 98,493.9 ng/ml; IgA T4GMC: 187.5 ng/ml) and saliva (IgG T4GMC: 21.9 ng/ml; IgA T4GMC: 0.65 ng/ml). Moreover, the booster re-established the neutralizing activity in the serum of all individuals, not only against the Wuhan wild-type antigen (N = 50; INH: 91.6%) but also against the variants (Delta INH: 91.3%; Delta Plus INH: 89.8%; Omicron BA.1 INH: 85.1%). By contrast, the salivary neutralizing activity was high against the Wuhan antigen in 72% of individuals (N = 36, INH: 62.2%), but decreased against the variants, especially against the Omicron BA.1 variant (Delta N = 27, INH: 43.1%; Delta Plus N = 24, INH: 35.2%; Omicron BA.1 N = 4; INH: 4.7%). This was suggestive for a different behaviour of systemic immunity observed in serum with respect to mucosal immunity described in saliva (Wald chi-square test, 3 df of interaction between variants and sample type = 308.2, p < 0.0001). INTERPRETATION: The BNT162b2-booster vaccination elicits a strong systemic immune response but fails in activating an effective mucosal immunity against the Omicron BA.1 variant. FUNDING: This work was funded by the Department of Medicine and Surgery, University of Insubria, and supported by Fondazione Umberto Veronesi (COVID-19 Insieme per la ricerca di tutti, 2020), Italy.

Attitude towards Intranasal Vaccines and Psychological Determinants: Effects on the General Population in Northern Italy.

Little is known about the use of intranasal vaccines, but some studies have shown that this innovative way of administration is preferred over needle injection as it is considered both less painful and intrusive to the body, equally effective, and associated with fewer side effects. This study aimed to investigate specific psychological determinants (intolerance of uncertainty, persecutory ideation, perceived control, vaccine hesitancy) of attitude toward nasal vaccine delivery. A convenience sample including 700 Italian participants took part in this cross-sectional study and completed an online questionnaire. A structural equation model with a latent variable was performed to study the relationship between psychological variables, vaccine hesitancy, and attitude toward nasal vaccine delivery. The results indicate that both a hesitant attitude toward vaccination (ß = 0.20, p = 0.000) and low perceived control (ß = -0.20, p = 0.005) may directly increase preference for nasal administration; furthermore, high levels of persecutory ideation may indirectly influence the propensity for intranasal vaccine. These findings suggest that pharmaceutical companies could implement nasal vaccines and provide detailed information on these vaccines through informational campaigns. Hesitant individuals with low levels of perceived control could more easily comply with these types of vaccines.

Detection of Torquetenovirus and Redondovirus DNA in Saliva Samples from SARS-CoV-2-Positive and -Negative Subjects.

OBJECTIVES: Torquetenovirus (TTV) and Redondovirus (ReDoV) are the most prevalent viruses found in the human respiratory virome in viral metagenomics studies. A large-scale epidemiological study was performed to investigate their prevalence and loads in saliva samples according to SARS-CoV-2 status. METHODS: Saliva samples from 448 individuals (73% SARS-CoV-2 negative and 27% SARS-CoV-2 positive) aged 23-88 years were tested. SARS-CoV-2 and TTV were determined in saliva by specific qualitative and quantitative real-time PCRs, respectively. A sub-cohort of 377 subjects was additionally tested for the presence and load of ReDoV in saliva, and a different sub-cohort of 120 subjects for which paired saliva and plasma samples were available was tested for TTV and ReDoV viremia at the same timepoints as saliva. RESULTS: TTV in saliva was 72% prevalent in the entire cohort, at a mean DNA load of 4.6 log copies/mL, with no difference regardless of SARS-CoV-2 status. ReDoV was found in saliva from 61% of the entire cohort and was more prevalent in the SARS-CoV-2-negative subgroup (65% vs. 52%, respectively). In saliva, the total mean load of ReDoV was very similar to the one of TTV, with a value of 4.4 log copies/mL. The mean viral loads in subjects infected with a single virus, namely, those infected with TTV or ReDoV alone, was lower than in dually infected samples, and Tukey's multiple-comparison test showed that ReDoV single-infected samples resulted in the only true outlier (p = 0.004). Differently from TTV, ReDoV was not detected in any blood samples. CONCLUSIONS: This study establishes the prevalence and mean value of TTV and ReDoV in saliva samples and demonstrates the existence of differences between these two components of the human virome.

Interleukin-1 and the NLRP3 inflammasome in COVID-19: Pathogenetic and therapeutic implications.

A hyperinflammatory response during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection crucially worsens clinical evolution of coronavirus disease 2019 (COVID-19). The interaction between SARS-CoV-2 and angiotensin-converting enzyme 2 (ACE2) triggers the activation of the NACHT, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) inflammasome. Enhanced inflammasome activity has been associated with increased disease severity and poor prognosis. Evidence suggests that inflammasome activation and interleukin-1ß (IL-1ß) release aggravate pulmonary injury and induce hypercoagulability, favoring progression to respiratory failure and widespread thrombosis eventually leading to multiorgan failure and death. Observational studies with the IL-1 blockers anakinra and canakinumab provided promising results. In the SAVE-MORE trial, early treatment with anakinra significantly shortened hospital stay and improved survival in patients with moderate-to-severe COVID-19. In this review, we summarize current evidence supporting the pathogenetic role of the NLRP3 inflammasome and IL-1ß in COVID-19, and discuss clinical trials testing IL-1 inhibition in COVID-19.

Dopaminergic inhibition of human neutrophils is exerted through D1-like receptors and affected by bacterial infection.

Dopamine (DA) affects immune functions in healthy subjects (HS) and during disease by acting on D1-like (D1 and D5) and D2-like (D2, D3 and D4) dopaminergic receptors (DR); however, its effects on human polymorphonuclear leukocytes (PMN) are still poorly defined. We investigated DR expression in human PMN and the ability of DA to affect cell migration and reactive oxygen species (ROS) production. Experiments were performed on cells from HS and from patients (Pts) with bacterial infections as well, during the acute phase and after recovery. Some experiments were also performed in mice knockout (KO) for the DRD5 gene. PMN from HS express both D1-like and D2-like DR, and exposure to DA results in inhibition of activation-induced morphological changes, migration and ROS production which depend on the activation of D1-like DR. In agreement with these findings, DA inhibited migration of PMN obtained from wild-type mice, but not from DRD5KO mice. In Pts with bacterial infections, during the febrile phase D1-like DRD5 on PMN were downregulated and DA failed to affect PMN migration. Both D1-like DRD5 expression and DA-induced inhibition of PMN migration were however restored after recovery. Dopaminergic inhibition of human PMN is a novel mechanism which is likely to play a key role in the regulation of innate immunity. Evidence obtained in Pts with bacterial infections provides novel clues for the therapeutic modulation of PMN during infectious disease.

Immune-Mediated Mechanisms in Patients Testing Positive for SARS-CoV-2: Protocol for a Multianalysis Study.

BACKGROUND: The novel coronavirus has a high mortality rate (over 1% for patients older than 50 years). This can only be partially ascribed to other comorbidities. A possible explanation is a factor that assures a prompt response to SARS-CoV-2 in younger people, independent from the novelty of the virus itself. A factor is believed to stimulate the immune system and provide immunity against more antigens. The only external stimulation received by healthy people is vaccination (eg, the diphtheria, tetanus, and pertussis [DTP] vaccine). One hypothesis is that vaccination helps develop specific immunity but generates sprouting immunity against antigens in transit. The underlying immunological phenomena are the "bystander effect" and "trained immunity." The developed immunity gives protection for years until it naturally fades out. After the fifth decade of life, the immune system is almost incompetent when a viral infection occurs, and thus, at this stage, the novel coronavirus can enter the body and cause acute respiratory distress syndrome. OBJECTIVE: The initial aim is to demonstrate that blood monocytes and natural killer cells show overpowering hyperactivity, while CD4+ and CD8+ T cells experience impediments to their defensive functions in patients with severe SARS-CoV-2 infection. The secondary objectives are to correlate clinical data and vaccination history with laboratory immune patterns in order to identify protective factors. Subsequently, we are also interested in characterizing the phenotypes and state of the degree of activation of peripheral blood mononuclear cells, including monocytes, natural killer cells, and CD4+ and CD8+ T cells, in healthy subjects vaccinated with the Pfizer vaccine. METHODS: Data will be collected using the following 3 approaches: (1) an experimental analysis to study the innate immune response and to identify genetic profiles; (2) an epidemiological analysis to identify the patients' vaccination history; and (3) a clinical analysis to detect the immunological profile. RESULTS: The protocol was approved by the Ethics Committee on April 16, 2020, and the study started on April 27, 2020. As of February 2021, enrollment has been completed. Immunological analysis is ongoing, and we expect to complete this analysis by December 2022. CONCLUSIONS: We will recognize different populations of patients, each one with a specific immunological pattern in terms of cytokines, soluble factor serum levels, and immune cell activity. Anamnestic data, such as preceding vaccinations and comorbidities, biochemical findings like lymphocyte immunophenotyping, and pre-existing persistent cytomegalovirus infection, allow depicting the risk profile of severe COVID-19. Proof of the roles of these immunological phenomena in the development of COVID-19 can be the basis for the implementation of therapeutic immunomodulatory treatments. TRIAL REGISTRATION: ClinicalTrials.gov NCT04375176; https://clinicaltrials.gov/ct2/show/NCT04375176. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/29892.

Mucosal immune response in BNT162b2 COVID-19 vaccine recipients.

BACKGROUND: Although the BNT162b2 COVID-19 vaccine is known to induce IgG neutralizing antibodies in serum protecting against COVID-19, it has not been studied in detail whether it could generate specific immunity at mucosal sites, which represent the primary route of entry of SARS-CoV-2. METHODS: Samples of serum and saliva of 60 BNT162b2-vaccinated healthcare workers were collected at baseline, two weeks after the first dose and two weeks after the second dose. Anti-S1-protein IgG and IgA total antibodies titres and the presence of neutralizing antibodies against the Receptor Binding Domain in both serum and saliva were measured by quantitative and by competitive ELISA, respectively. FINDINGS: Complete vaccination cycle generates a high serum IgG antibody titre as a single dose in previously infected seropositive individuals. Serum IgA concentration reaches a plateau after a single dose in seropositive individuals and two vaccine doses in seronegative subjects. After the second dose IgA level was higher in seronegative than in seropositive subjects. In saliva, IgG level is almost two orders of magnitude lower than in serum, reaching the highest values after the second dose. IgA concentration remains low and increases significantly only in seropositive individuals after the second dose. Neutralizing antibody titres were much higher in serum than in saliva. INTERPRETATION: The mRNA BNT162b2 vaccination elicits a strong systemic immune response by drastically boosting neutralizing antibodies development in serum, but not in saliva, indicating that at least oral mucosal immunity is poorly activated by this vaccination protocol, thus failing in limiting virus acquisition upon its entry through this route. FUNDING: This work was funded by the Department of Medicine and Surgery, University of Insubria, and partially supported by Fondazione Umberto Veronesi (COVID-19 Insieme per la ricerca di tutti, 2020).

Performance Assessment of the LIAISON® SARS-CoV-2 Antigen Assay On Nasopharyngeal Swabs.

The SARS-CoV-2 pandemic is ongoing worldwide, causing prolonged pressure on molecular diagnostics. Viral antigen (Ag) assays have several advantages, ranging from lower cost to shorter turnaround time to detection. Given the rare occurrence of low-load viremia, antigen assays for SARSCoV-2 have focused on nasopharyngeal swab and saliva as biological matrices, but their effectiveness must be validated. We assayed here the performances of the novel quantitative Liaison® SARSCoV-2 Ag assay on 119 nasopharyngeal swabs and obtained results were compared with Hologic Panther and Abbott m2000 RT-qPCR. The Ag assay demonstrated a good correlation with viral load, shorter turnaround time, and favorable economics. The best performance was obtained in the acute phase of disease.

Spike protein evolution in the SARS-CoV-2 Delta variant of concern: a case series from Northern Lombardy.

The SARS-CoV-2 variant of concern (VOC) "Delta" is currently defined by PANGOLIN as a cluster of 33 different AY sublineages. Delta (in particular B.1.617.2) is largely and rapidly replacing the Alpha VOC as the dominant clade in most countries. To date, variations in the Spike protein of the Delta VOC have largely been limited. We report here the results of a genomic surveillance programme from Northern Italy. We identified several Delta sublineages harbouring mutations previously reported in GISAID at extremely low frequencies and in different combinations. Two patients (one of them vaccinated) tested positive for a Delta sublineage harbouring S71F, T250I, T572I and K854N. More patients tested positive for G769 V plus C1248F, A352S, and R158G and C1248F, respectively. Genomic surveillance of Delta variants should be encouraged to anticipate immune escape and deploy countermeasures.

Characterization of a Lineage C.36 SARS-CoV-2 Isolate with Reduced Susceptibility to Neutralization Circulating in Lombardy, Italy.

SARS-CoV-2 spike is evolving to maximize transmissibility and evade the humoral response. The massive genomic sequencing of SARS-CoV-2 isolates has led to the identification of single-point mutations and deletions, often having the recurrence of hotspots, associated with advantageous phenotypes. We report the isolation and molecular characterization of a SARS-CoV-2 strain, belonging to a lineage (C.36) not previously associated with concerning traits, which shows decreased susceptibility to vaccine sera neutralization.

Indocyanine Green Angiography for Quality Assessment of the Kidney During Transplantation: An Outcome Predictor Prospective Study.

BACKGROUND: Microvascular damage is the main cause of delayed graft function (DGF) after kidney transplant. Assessing its extent may be helpful in predicting DGF to achieve better postoperative management, especially in terms of an immunosuppressive regimen. Our aim was to explore the capability of intraoperative indocyanine green (ICG) angiography to examine the microvasculature of the kidney. METHODS: We conducted a prospective cohort study on 37 kidney transplant recipients in a high-volume kidney transplant center. During surgery, after graft implant, an ICG angiography was performed through a high-definition Storz camera system (Karl Storz GmbH, Tuttlingen, Germany) with successive quantitative assessment of fluorescence using Icy bioimage analysis. RESULTS: All transplanted kidneys that showed immediate recovery of their function had a fluorescent intensity ≥49.953 with a mean of 96.930 ± 21. The fluorescence intensity for kidneys that showed a delayed recovery of their function never exceeded 55.648, and the mean was 37.718 ± 13. The difference between the 2 groups was statistically significant with a P value < .001. The only kidney that never recovered showed a fluorescence intensity consistently <25.220, the lowest detected. CONCLUSIONS: This study demonstrates that intraoperative ICG angiography may be used to assess the microvasculature of the graft. A statistically significant difference in terms of fluorescent intensity can be highlighted between kidneys that immediately recover their function and those with delayed recovery. Further larger studies are needed to confirm the capability of the technique to predict DGF to optimize the transplanted patients' management.

High-dose dexamethasone treatment for COVID-19 severe acute respiratory distress syndrome: a retrospective study.

Low-dose dexamethasone reduces mortality in patients with coronavirus disease 2019 (COVID-19)-related acute respiratory distress syndrome (ARDS). We retrospectively analyzed the efficacy of high-dose dexamethasone in patients with COVID-19-related ARDS and evaluated factors affecting the composite outcome (death or invasive mechanical ventilation). From March 4th to April 1st 2020, 98 patients with COVID-19 pneumonia were included. Those who after at least 7 days from symptom onset presented a worsening of the respiratory function or of inflammatory biomarkers were started on intravenous high-dose dexamethasone (20 mg daily for 5 days, followed by 10 mg daily for 5 days). Most patients were males (62%) with a mean age of 69 years. Hypertension and cardiovascular disease (CVD) were prevalent. Following dexamethasone treatment, a significant improvement in PaO2/FiO2 (277.41 [178.5-374.8] mmHg vs. 146.75 [93.62-231.16] mmHg, p < 0.001), PaO2 (88.15 [76.62-112.0] mmHg vs. 65.65 [57.07-81.22] mmHg, p < 0.001), and SpO2 (96 [95-98]% vs. 94 [90-96]%, p < 0.001) was observed. A concomitant decrease in C-reactive protein and ferritin levels was found (132.25 [82.27-186.5] mg/L vs. 7.3 [3.3-24.2] mg/L and 1169 [665-2056] ng/mL vs. 874.0 [569.5-1434] ng/mL, respectively; p < 0.001 for both vs. baseline). CVD was found to increase the risk of the composite outcome (RR 7.64, 95% CI 1.24-47.06, p = 0.028). In hospitalized patients with COVID-19-related ARDS, high-dose dexamethasone rapidly improves the clinical status and decreases inflammatory biomarkers. CVD was found to increase the risk of the composite outcome. These data support the importance of randomized clinical trials with high-dose dexamethasone in COVID-19 patients.

Epidemiology of Pediatric Surgical Conditions Observed in a First-Level Hospital in Burundi.

Background: Little is known about the surgical conditions affecting the pediatric population in low-income countries. In this article we describe the epidemiology of pediatric surgical diseases observed in Mutoyi hospital, a first-level hospital in Burundi. Methods and Findings: We retrospectively reviewed the records of all children (0-14 years) admitted to the Surgery ward from January 2017 to December 2017. We also reviewed the records of all the patients admitted to the Neonatology ward in 2017 and among them we selected the ones in which a surgical diagnosis was present. Five hundred twenty-eight children were admitted to the surgical ward during the study period. The most common conditions requiring hospitalization were abscesses (29.09%), fractures (13.59%), osteomyelitis (9.76%), burns (5.40%) and head injuries (4.36%). The average length of stay was 16 days. Fifty-six newborns were admitted to the Neonatology ward for a surgical condition; 29% of them had an abscess. Conclusions: Conditions requiring surgical care are frequent in Burundian children and have a completely different spectrum from the western ones. This is due on one side to an under-diagnosis of certain conditions caused by the lack of diagnostic tools and on the other to the living conditions of the population. This difference should lead to intervention plans tailored on the actual necessities of the country and not on the western ones.

Time Trends of Percutaneous Injuries in Hospital Nurses: Evidence of the Interference between Effects of Adoption of Safety Devices and Organizational Factors.

Few studies have focused on the combined effects of devices and work organization on needlestick injuries trends. The aim of the study was to estimate trends of percutaneous injury rates (IR) in nurses (N) and nurse assistants (NA) over a 10 year period, in which passive safety devices were progressively adopted. Percutaneous and mucocutaneous injuries registered in a University Hospital in Northern Italy in Ns and NAs in 2007-2016 were analyzed. Organizational data were also available on shift schedules, turnover, downsizing and age- and skill-mix. We estimated IRs per 100 full-time equivalent workers from Poisson models and their average annual percent changes (APC) from joinpoint regression model. In the entire period, monotonic decreases in percutaneous IRs occurred among day-shift Ns (APC = -20.9%; 95% CI: -29.8%, -12%) and NAs (APC = -15.4%; -32.9%, 2.2%). Joinpoint modeling revealed a turning point in 2012 for night-shift Ns, with a steady decline in 2007-2012 (APC = -19.4%; -27.9%, -10.9%), and an increase thereafter (APC = +13.5%; 1.5%, 25.5%). In comparison to 2008 and 2012, in 2016 night-shift Ns were 5.9 and 2.5 times more likely to be younger and less qualified or experienced than day-shift Ns. The observed declines in percutaneous injury rates occurred in a time period when safety devices were progressively implemented. The causal nature of multiple exposures and organizational procedures in affecting injury time trends should be further addressed by quasi-experimental studies.

In Vitro Evaluation of the Effect of a Not Cross-Linked Hyaluronic Acid Hydrogel on Human Keratinocytes for Mesotherapy.

The multicomponent preparations for mesotherapy are based on the principle that skin and hair aging can be prevented by supplying the fundamental substrates for correct cellular functioning, such as nucleotides, vitamins, amino acids, and biomolecules including hyaluronic acid (HA) that promote skin hydration and several biological activities. The study provides evidence for the application of HYDRO DELUXE BIO (Matex Lab S.p.A), a biocompatible hydrogel containing not cross-linked HA, for the treatment of the scalp's skin by mesotherapy. Using an in vitro model of immortalized human keratinocytes, we studied markers involved in hair aging prevention and growth, such as inflammatory markers, angiogenesis, and oxidative damage. HYDRO DELUXE BIO showed high biocompatibility and the ability to significantly reduce the expression of the inflammation marker interleukin (IL)-8 in Tumor Necrosis Factor (TNF)-stimulated cells. Then, we evaluated angiogenesis, a pivotal event during hair growth, measuring the Vascular Endothelial Growth Factor (VEGF) expression that resulted to be significantly increased in treated cells, suggesting a pro-angiogenetic capability. A protective activity against the oxidative stress agent was showed, increasing the survival rate in treated cells. Concluding, HYDRO DELUXE BIO is suitable for treatment by mesotherapy of the scalp's skin as it modulates the expression levels of markers involved in the biorevitalization of the hair follicle.

Combined laser assisted treatment for permanent hair removal for skin types I-V with Alexandrite 755 nm and ND:YAG 1064 nm lasers.

This retrospective cohort study regarding hair removal procedures considers all the data collected in three different clinical centers from 2017 to 2019. The device used to perform the treatments was composed of an Alexandrite 755 nm and an Nd:YAG 1064 nm laser, that delivered both wavelengths in a blended simultaneous emission (Thunder MT, Quanta System, Samarate, Italy). The improvement evaluated after five sessions of treatment by an external referee was: 83.0% for armpits, 82.1% for the bikini line, 82.2% for legs, 79.6% for thorax, and 81.6% for the back. The collected temporary skin reaction data reported in this study were all acceptable and transitory resolving in less than 1 week. The level of erythema and perifollicular edema were all signs of the reached treatment endpoint. First degree burns, hyper, and hypopigmentation were also reported in a few cases but these, all resolved before the follow-up visit without any permanent skin effects. No adverse effects were thus reported to have happened. This retrospective study demonstrates the efficacy of combining Alexandrite and Nd:YAG lasers in a mixed modality with simultaneous emission. This technology permitted to treat patients with skin types I-V without any reported permanent side effects and with a high pain tolerability compared to the use of Nd:YAG in single mode.