Impact of SARS-CoV-2 Omicron and Delta variants in patients requiring intensive care unit (ICU) admission for COVID-19, Northern Italy, December 2021 to January 2022

This multicenter observational study included 171 COVID-19 adult patients hospitalized in the ICUs of nine hospitals in Lombardy (Northern Italy) from December, 1st 2021, to February, 9th 2022. During the study period, the Delta/Omicron variant ratio of cases decreased with a delay of two weeks in ICU patients compared to that in the community; a higher proportion of COVID-19 unvaccinated patients was infected by Delta than by Omicron whereas a higher rate of COVID-19 boosted patients was Omicron-infected. A higher number of comorbidities and a higher comorbidity score in ICU critically COVID-19 inpatients was positively associated with the Omicron infection as well in vaccinated individuals. Although people infected by Omicron have a lower risk of severe disease than those infected by Delta variant, the outcome, including the risk of ICU admission and the need for mechanical ventilation due to infection by Omicron versus Delta, remains uncertain. The continuous monitoring of the circulating SARS-CoV-2 variants remains a milestone to counteract this pandemic.

Immunogenicity and effectiveness of BNT162b2 COVID-19 vaccine in a cohort of healthcare workers in Milan (Lombardy Region, Northern Italy)

OBJECTIVES

to evaluate immunogenicity and effectiveness of BNT162b2 COVID-19 vaccine in a cohort of healthcare workers (HCWs).

DESIGN

cohort study.

SETTING AND PARTICIPANTS

in a hospital in Milan (Lombardy Region, Northern Italy) HCWs without ("negative cohort") and with ("positive cohort") history of SARS-CoV-2 infection or elevated serum antibody before the vaccination campaign (27.12.2020) were included. Data collection and follow-up covered the period 27.12.2020-13.05.2022.

MAIN OUTCOMES MEASURES

1. serum anti-spike-1 (anti-S1) antibody levels after vaccination; 2. vaccine effectiveness (VE) against SARS-CoV-2 infections (either symptomatic or not) in the negative cohort. Data on infections were extracted from multiple sources (laboratory, accident reports, questionnaires). Vaccination was treated as a time-dependent variable. Using unvaccinated person-time as reference, hazard ratios (HR) of infections and 95% confidence intervals (95%CI) were calculated with a Cox regression model adjusted for gender, age, and occupation. VE was calculated as (1 - HR)×100.

RESULTS

5,596 HCWs were included, 4,771 in the negative and 825 in the positive cohort. In both cohorts, serum anti-S1 antibodies were high one months after the second dose, halved after six months, and returned to high levels after the third dose. In the negative cohort, 1,401 SARS-CoV-2 infections were identified. VE was 70% (95%CI 54-80; 46 infected) in the first four months after the second dose and later declined to 16% (95%CI 0-43; 97 infected). After the third dose, VE increased to 57% (95%CI 35-71; 61 infected) in the first month but rapidly declined over time, particularly after three months (24% in the fourth month and 1% afterwards). The number of infections avoided by vaccination was estimated to be 643 (95%CI 236-1,237).

CONCLUSIONS

in spite of rapidly declining effectiveness, vaccination helped to avoid several hundred infections in the considered hospital.

Epidemiology and antibiotic resistance in community-acquired lower urinary tract infections in the Milan area

Urinary tract infections (UTIs) are among the most common bacterial infectious diseases occurring in the community and healthcare setting. Most community-acquired urinary tract infections are usually treated empirically. The knowledge of antibiotic resistance patterns of the microorganisms causing UTI is essential for defining the empirical treatment. The aim of the present study is to investigate the prevalence and the resistance patterns of bacterial species isolated from lower urinary tract infections, in a large population of Milan area. A retrospective analysis of the isolates obtained from urine samples received at the microbiology laboratory of Centro Diagnostico Italiano of Milan was performed from January 2019 to December 2019. Urine samples were plated on differential medium by automated inoculation system. Identification and antibiotic susceptibility testing were performed using the Phoenix 100™ system. All results were interpreted according to the European Committee on Antimicrobial Susceptibility Testing breakpoints. During a 12-month period a total of the 51,980 urine samples have been processed and 21,4% (11.148) were found to be positive (bacterial count ≥105CFU/mL). Overall Escherichia coli was the most common Gram-negative bacteria of all isolates (72%), followed by Klebsiella pneumoniae (10.8%) and Proteus mirabilis (3.3%). Susceptibility of E. coli to oral antimicrobial agents was demonstrated to be as follows: fosfomycin (97%), trimethoprim/sulfamethoxazole (76%), ciprofloxacin (89%), ampicillin (51%) and amoxicillin/clavulanate (77%). The present study point-out the common antibiotic resistance trend of uropathogens in this area. Our results will help in the formulation of antibiotic policy and determination of empirical treatment of urinary tract infection.

Clinical and socioeconomic impact of different types and subtypes of seasonal influenza viruses in children during influenza seasons 2007/2008 and 2008/2009

Background

There are few and debated data regarding possible differences in the clinical presentations of influenza A/H1N1, A/H3N2 and B viruses in children. This study evaluates the clinical presentation and socio-economic impact of laboratory-confirmed influenza A/H1N1, A/H3N2 or B infection in children attending an Emergency Room because of influenza-like illness.

Methods

Among the 4,726 children involved, 662 had influenza A (143 A/H1N1 and 519 A/H3N2) and 239 influenza B infection detected by means of real-time polymerase chain reaction. Upon enrolment, systematic recordings were made of the patients' demographic characteristics and medical history using standardised written questionnaires. The medical history of the children was re-evaluated 5-7 days after enrolment and until the resolution of their illness by means of interviews and a clinical examination by trained investigators using standardised questionnaires. During this evaluation, information was also obtained regarding illnesses and related morbidity among households.

Results

Children infected with influenza A/H1N1 were significantly younger (mean age, 2.3 yrs) than children infected with influenza A/H3N2 (mean age, 4.7 yrs; p < 0.05)) or with influenza B (mean age, 5.2 yrs; p < 0.05). Adjusted for age and sex, children with influenza A/H3N2 in comparison with those infected by either A/H1N1 or with B influenza virus were more frequently affected by fever (p < 0.05) and lower respiratory tract involvement (p < 0.05), showed a worse clinical outcome (p < 0.05), required greater drug use (p < 0.05), and suffered a worse socio-economic impact (p < 0.05). Adjusted for age and sex, children with influenza B in comparison with those infected by A/H1N1 influenza virus had significantly higher hospitalization rates (p < 0.05), the households with a disease similar to that of the infected child (p < 0.05) and the need for additional household medical visits (p < 0.05).

Conclusions

Disease due to influenza A/H3N2 viral subtype is significantly more severe than that due to influenza A/H1N1 subtype and influenza B virus, which indicates that the characteristics of the different viral types and subtypes should be adequately considered by health authorities when planning preventive and therapeutic measures.

Immunogenicity, safety and tolerability of monovalent 2009 pandemic influenza A/H1N1 MF59-adjuvanted vaccine in children and adolescents with Williams or Cornelia De Lange syndrome

In some subjects with severe neurological diseases, a reduced immune response to seasonal influenza vaccine has been demonstrated. Patients with Williams or Cornelia de Lange syndrome frequently have abnormalities in neurodevelopment. This study has evaluated the immunogenicity, safety and tolerability of a monovalent 2009 pandemic influenza A/H1N1 MF59-adjuvanted vaccine in these subjects. Eighteen patients with Williams syndrome (ten males; mean age ± standard deviation [SD] 12.74 ± 4.49 years), 11 with Cornelia de Lange syndrome (six males; mean age 12.90 ± 4.85 years) and 30 age- and gender-matched healthy controls (16 males; mean age 12.49 ± 4.55 years), never vaccinated against influenza, received a dose of the vaccine between 1 and 30 November 2009. Four weeks later, the seroconversion rates in the three groups were between 72% and 80% and the seroprotection rates were 100%, with a similar increase in antibody levels. Two months later, most of the subjects remained seroconverted with no statistically significant difference between the groups, and about 94% of the patients with Williams syndrome, all of those with Cornelia de Lange syndrome and all of the healthy controls were still seroprotected. Safety and tolerability were very good, with no difference between the groups. None of the patients developed documented influenza during the study period. These results show that the immunogenicity, safety, and tolerability of a single dose of the monovalent 2009 pandemic influenza A/H1N1 MF59-adjuvanted vaccine in children and adolescents with Williams or Cornelia de Lange syndrome and moderate to severe mental disabilities is very good, and similar to that of healthy subjects.

Influenza A/H1N1 MF59-adjuvanted vaccine in preterm and term children aged 6 to 23 months

OBJECTIVE

This study was designed to evaluate the immunogenicity, safety, and tolerability of a monovalent 2009 pandemic influenza A/H1N1 MF59-adjuvanted vaccine in children aged 6 to 23 months who had different gestational ages (GAs) at birth.

METHODS

The study involved 105 children: 35 preterm subjects with a GA of <32 weeks; 35 preterm subjects with a GA of 32 to 36 weeks; and 35 term subjects with a GA of 37 to 42 weeks. Each child received 2 intramuscular vaccine doses (Focetria [Novartis, Siena, Italy]): dose 1 at enrollment and dose 2 after 4 weeks (28 ± 2 days). Serum samples for antibody measurements were collected immediately before administration of dose 1, before administration of dose 2 (28 ± 2 days after baseline), and 4 weeks later (56 ± 2 days after baseline). Local and systemic reactions were assessed during the 14 days after each vaccination.

RESULTS

Of the 101 children who completed the study 32 out of 34 preterm subjects with a GA of <32 weeks, all of the preterm subjects with a GA of 32 to 36 weeks, and all of the term subjects seroconverted and were seroprotected after the first vaccine dose. Local and systemic tolerability was good in all of the groups, but fever was significantly more common after the first dose than after the second dose (P < .05), and there were no between-group differences.

CONCLUSIONS

A single dose of 2009 pandemic influenza A/H1N1 MF59-adjuvanted vaccine evoked a significant immune response against pandemic influenza A/H1N1 virus in children aged 6 to 23 months even if their GA was <32 weeks. The vaccine had a good safety and tolerability profile.

An open-label, randomized clinical trial assessing immunogenicity, safety and tolerability of pandemic influenza A/H1N1 MF59-adjuvanted vaccine administered sequentially or simultaneously with seasonal virosomal-adjuvanted influenza vaccine to paediatric kidney transplant recipients

Background. The aim of this study was to investigate the immunogenicity, safety and tolerability of the 2009 A/H1N1 MF59-adjuvanted influenza vaccine, administered sequentially or simultaneously with the seasonal 2009–10 virosomal-adjuvanted influenza vaccine, to paediatric kidney transplant recipients.

Methods. Thirty-two children and adolescents with transplanted kidneys and 32 age- and gender-matched healthy controls were randomized 1:1 to receive the pandemic vaccine upon enrolment and the seasonal vaccine 1 month later (16 transplant recipients and 16 healthy controls), or to receive the two vaccines simultaneously upon enrolment (16 transplant recipients and 16 healthy controls).

Results. When the pandemic vaccine was administered sequentially to the seasonal vaccine, it was significantly less immunogenic in the patients than in the controls (P < 0.05); when it was administered together with the seasonal vaccine, the immune response of both patients (P < 0.05) and controls (P < 0.05) was significantly greater than when it was administered sequentially. Seroconversion rates and the geometric mean titres of all of the seasonal antigens were significantly lower in the patients, regardless of the type of vaccine administration (P < 0.05). Simultaneous administration was associated with a better immune response against A/H1N1 and A/H3N2 antigens in both patients and controls, and did not increase the mild local and systemic reactions. No impact on renal function was observed.

Conclusions. Paediatric kidney transplant recipients have a lower immune response to the pandemic influenza A/H1N1 MF59-adjuvanted and seasonal virosomal-adjuvanted influenza vaccines than healthy controls. The simultaneous administration of the two vaccines seems to increase immune response to both pandemic and seasonal A/H1N1 and A/H3N2 antigens, and has the same safety profile as that of the pandemic vaccine administered sequentially to the seasonal vaccine.

Clinical importance and impact on the households of oseltamivir-resistant seasonal A/H1N1 influenza virus in healthy children in Italy

A resistance of A/H1N1 influenza viruses to oseltamivir has recently emerged in a number of countries. However, the clinical and socioeconomic importance of this resistance has not been precisely defined. As children have the highest incidence of influenza infection and are at high risk of severe disease, the aim of this study was to evaluate the clinical importance and the impact on the households of oseltamivir-resistant seasonal A/H1N1 influenza virus in an otherwise healthy pediatric population. A total of 4,726 healthy children younger than 15 years with influenza-like illness were tested for influenza viruses by real-time polymerase chain reaction in the winters of 2007-2008 and 2008-2009 in Italy. The influenza A virus-positive samples underwent neuraminidase gene analysis using pyrosequencing to identify mutations H275Y and N294 S in A/H1N1, and E119V, R292K, and N294 S in A/H3N2. Among the A/H1N1 subtypes, the H275Y mutation was found in 2/126 samples taken in 2007-2008 (1.6%) and in all 17 samples (100%; p < 0.0001) taken in 2008-2009. No other mutation was identified in any of the A/H1N1 or A/H3N2 influenza viruses. No significant differences were found in terms of clinical importance or impact on the households between the children with oseltamivir-resistant seasonal A/H1N1 influenza virus and those with the wild-type. The spread of H275Y-mutated A/H1N1 seasonal influenza virus is a common phenomenon and the clinical importance and impact on the households of the mutated virus is similar to that of the wild-type in an otherwise healthy pediatric population.

Collection by trained pediatricians or parents of mid-turbinate nasal flocked swabs for the detection of influenza viruses in childhood

This study evaluated the efficiency of pediatric mid-turbinate nasal flocked swabs used by parents in 203 children aged 6 months to 5 years with signs and symptoms of respiratory disease. Two nasal samples were collected from each child in a randomised sequence: one by a trained pediatrician and one by a parent. The real-time polymerase chain reaction influenza virus detection rates were similar in the samples collected using the two methods (Cohen's kappa = 0.86), as were the cycle threshold values. In comparison with the pediatrician-collected samples, the sensitivity and specificity of the parental collections were respectively 89.3% (95% confidence interval [CI]: 77.8-100%) and 97.7% (95% CI: 95.5-100%), and the positive and negative predictive values were respectively 86.2% (95% CI: 73.7-95.1%) and 98.2% (95% CI: 96.4-100%). The children were significantly more satisfied with the parental collections (median values ± standard deviation, 1.59 ± 0.55 vs 3.51 ± 0.36; p < 0.0001). These findings show that mid-turbinate nasal flocked swabs specifically designed for infants and children can be used by parents without reducing the influenza virus detection rate. Moreover, the direct involvement of parents significantly increases patient acceptance, thus simplifying collection and suggesting that this novel swab design should be considered for epidemiological surveys and vaccine efficacy studies.

Comparison of nasopharyngeal nylon flocked swabs with universal transport medium and rayon-bud swabs with a sponge reservoir of viral transport medium in the diagnosis of paediatric influenza

This study compared a kit containing a nasopharyngeal nylon flocked swab and a tube with a liquid universal transport medium (UTM) with a kit containing a plastic-shafted rayon-budded swab with a sponge reservoir of viral transport medium for the molecular detection of influenza viruses in children. Respiratory samples were collected from 314 children aged <5 years with influenza-like illness (186 males; mean age 2.32±2.27 years) using both swabs in a randomized sequence for each patient. The flocked swabs permitted the detection of 28 influenza A (8.9 %) and 45 influenza B (14.3 %) cases, and the rayon-bud swabs 26 influenza A (8.3 %) and 43 influenza B (13.7 %) cases, with detection rates of 23.2 and 22.0 %, respectively, and similar cycle threshold values. Paediatricians and laboratory staff were significantly more satisfied with both the simplicity (P <0.0001) and rapidity (P <0.0001) of the nasopharyngeal flocked swabs with UTM. These findings show that the flocked swabs with UTM and the rayon-bud swabs with a sponge transport medium are similarly efficient in preserving influenza virus nucleic acid, but that the kit containing a flocked swab with a UTM allows easier and more rapid collection and processing of specimens.