Stevens-johnson syndrome associated with drugs and vaccines in children: a case-control study

Drugs associated with epidermal necrolysis in children: A World Health Organization pharmacovigilance database analysis

BACKGROUND

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare life-threatening mucocutaneous reactions most often induced by drugs. To date, no large pharmacovigilance study has been conducted in the paediatric population.

OBJECTIVES

To describe the spectrum of drugs associated with SJS-TEN in children through the analysis of cases reported in the WHO pharmacovigilance database (VigiBase).

METHODS

Disproportionality study using data from VigiBase. All paediatric (age under 18 years) cases reported between January 1, 1967, and July 6, 2022, were included. For each molecule, a case-non-case study was performed to assess a potential pharmacovigilance signal by computing the lower end of the 95% credibility interval for the information component (IC025). We performed sensitivity analyses, (i) taking into account only cases reported by physicians and (ii) taking into account only cases reported in the last 10 years.

RESULTS

Among 31,376,783 adverse drug reactions reported in VigiBase, 2,248,727 were paediatric cases and 7342 were encoded as paediatric SJS-TEN. Significant statistical pharmacovigilance signals were observed for 165 drugs. The two most represented drug classes were antiepileptics and anti-infectious drugs. The five drugs with the highest IC025 were lamotrigine (IC025 4.99), carbamazepine (IC025 4.88), phenobarbital (IC025 4.67), phenytoin (IC025 4.52) and nimesulide (IC025 4.23). Acetaminophen was significantly associated with paediatric SJS-TEN (IC025 2.85) and we also described various new suspected drugs. Vaccines had no significant pharmacovigilance signal. These results were confirmed with the sensitivity analyses.

CONCLUSIONS

This study updates the spectrum of drugs potentially associated with paediatric SJS-TEN.

Signal mining study of severe cutaneous adverse events of valaciclovir or acyclovir based on the FAERS database

OBJECTIVE

This study aimed to explore a comprehensive empirical investigation and assess SCARs related to valaciclovir or acyclovir based on FAERS database from FDA, thus providing a theoretical foundation for the rational application of drugs in clinic.

METHODS

SCARs reports relevant to valaciclovir or acyclovir were searched in FAERS database from the 2004 Q1 to 2023 Q2. These data were further mined by a proportional analysis and Bayesian approach to detect signals of SCARs caused by two drugs. Meanwhile, the clinical characteristics, onset time, correlation, and stratification analysis of the two drugs in SCARs were analyzed.

RESULTS

Both drugs exhibited positive signals for drug reaction with DRESS, AGEP, TEN, SJS-TEN overlap and SJS. The median onset time of SCARs caused by valaciclovir or acyclovir was 30 days vs 10 day for DRESS, 11 days vs 9 days for AGEP, 17 days vs 12 days (TEN) and 12 days vs 8 days (SJS). Excluding the effect of combinational drugs, there was an association between the two antiviral drugs and SCARs.

CONCLUSION

By analyzing the FAERS database, the risk trends of SCARs caused by valaciclovir or acyclovir have been identified, providing valuable insights to recognize various types of SCARs in clinics.

Clinical features and outcomes in children with Stevens-Johnson syndrome and toxic epidermal necrolysis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening cutaneous conditions. However, studies of pediatric SJS/TEN are limited. To investigate the causes, clinical course, outcomes and complications of SJS and TEN in children. This retrospective study included 47 pediatric patients (aged < 18 years) with SJS, SJS/TEN, or TEN treated at Chang Gung Memorial Hospital, Taiwan, between January 2009 and December 2019. ALDEN scores and serological tests were used to assess causes and SCORTEN scores were applied to evaluate disease severity. Forty-seven patients, including 30 with SJS, 6 with SJS/TEN, and 11 with TEN were included. Median age was 8 years (range 1-17 years); 51.1% were male. Thirty-three cases (70.2%) were caused by drugs and infectious pathogens were suspected in 14 cases (29.8%). Oxcarbazepine (5/47, 10.6%) and amoxicillin (5/47, 10.6%) were the most often-implicated drugs, and Mycoplasma infection (9/47, 19.1%) was the predominant infectious cause. Only one TENS patient died (mortality rate 1/47, 2.1%) due to septic shock with ARDS, acute renal failure and cardiopulmonary shock. Median hospital stay was 15.5 (3-42) days. Pulmonary involvement (2/39, 5.1%), including pneumonia and ARDS, was noted in acute stage. Long-term sequelae were ocular involvement (6/39, 15.4%), nail dystrophy (4/39, 10.3%) and post-inflammatory hypo-/hyperpigmentation (3/39, 7.7%). In the present study, pediatric patients with SJS, SJS/TEN, or TEN have good outcomes with few long-term complications and low mortality. Mycoplasma is the most common infectious cause in pediatric SJS/TEN. Ocular discomfort, nail dystrophy and skin dyschromia are common long-term sequelae requiring regular follow-up.

Drug-Induced Severe Cutaneous Adverse Reactions: Insights Into Clinical Presentation, Immunopathogenesis, Diagnostic Methods, Treatment, and Pharmacogenomics

SCARs are rare and life-threatening hypersensitivity reactions. In general, the increased duration of hospital stays and the associated cost burden are common issues, and in the worst-case scenario, they can result in mortality. SCARs are delayed T cell-mediated hypersensitivity reactions. Recovery can take from 2 weeks to many months after dechallenging the culprit drugs. Genetic polymorphism of the HLA genes may change the selection and presentation of antigens, allowing toxic drug metabolites to initiate immunological reactions. However, each SCARs has a different onset latency period, clinical features, or morphological pattern. This explains that, other than HLA mutations, other immuno-pathogenesis may be involved in drug-induced severe cutaneous reactions. This review will discuss the clinical morphology of various SCARs, various immune pathogenesis models, diagnostic criteria, treatments, the association of various drug-induced reactions and susceptible alleles in different populations, and the successful implementation of pharmacogenomics in Thailand for the prevention of SCARs.

An EAACI Task Force report on allergy to beta-lactams in children: Clinical entities and diagnostic procedures

Beta-lactam (BL) allergy suspicion is common in children and constitutes a major public health problem, with an impact on patient's health and on medical costs. However, it has been found that most of these reactions are not confirmed by a complete allergic workup. The diagnostic value of the currently available allergy tests has been investigated intensively recently by different groups throughout the world. This has led to major changes in the management of children with a suspected BL allergy. Particularly, it is now well accepted that skin tests can be skipped before the drug provocation test in children with a benign non-immediate reaction to BL. However, there is still a debate on the optimal allergic workup to perform in children with a benign immediate reaction. In addition, management of children with severe cutaneous adverse drug reactions remains difficult. In this review, based on a selection of the most relevant studies found in the literature, we will review and discuss the diagnosis of different forms of BL allergy in children.

A review of published cases of Stevens-Johnson syndrome and toxic epidermal necrolysis associated with the use of acetaminophen

PURPOSE

Acetaminophen (paracetamol) is a widely used analgesic and antipyretic. In several studies, its use was associated with the occurrence of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). This narrative review aimed to explore and summarise available cases of SJS/TEN suspected to be associated with acetaminophen reported in the literature.

MATERIALS AND METHODS

Electronic searches were conducted in PubMed/MEDLINE, Web of Science, Scopus and Serbian Citation Index (SCIndeks). Case reports or case series which reported detailed clinical description of the patients diagnosed with SJS, TEN or SJS/TEN overlap which was caused or suspected to be most likely caused by acetaminophen with available full text were included in the review.

RESULTS

Twenty-nine publications describing a total of 36 patients which satisfied inclusion criteria were included in the review. The age of the patients ranged from 3 to 77 years (median: 32.5 years). There were 15 female (41.7%) and 15 male (41.7%) patients, while for 6 patients (16.7%) gender was not reported. TEN, SJS and SJS/TEN overlap were diagnosed in 24 (66.7%), 10 (27.8%) and 2 (5.6%) patients, respectively. Reported time from the first dose of acetaminophen to the onset of the first symptoms of SJS/TEN ranged from promptly to 21 days, with a median of 3 days. Use of some form of supportive and symptomatic care was reported in 28 patients (77.8%). Systemic corticosteroids were reported to be administered in 25 patients (69.4%) and intravenous immunoglobulin in 16 patients (44.4%). All patients survived. Long-term consequences (sequelae) were reported in 5 patients (13.9%).

CONCLUSIONS

Clinicians should be aware that SJS/TEN may be an adverse effect of acetaminophen and keep in mind that its prompt recognition and withdrawal of the culprit drug along with supportive care is of utmost importance.

Delayed hypersensitivity to antiepileptic drugs in children

BACKGROUND

Antiepileptic drugs (AEDs) are widely used for the treatment of epilepsy, but they can be associated with the development of mainly delayed/non-immediate hypersensitivity reactions (HRs). Although these reactions are usually cutaneous, self-limited, and spontaneously resolve within days after drug discontinuation, sometime HR reactions to AEDs can be severe and life-threatening.

AIM

This paper seeks to show examples on practical management of AED HRs in children starting from a review of what it is already known in literature.

RESULTS

Risk factors include age, history of previous AEDs reactions, viral infections, concomitant medications, and genetic factors. The diagnostic workup consists of in vivo (intradermal testing and patch testing) and in vitro tests [serological investigation to exclude the role of viral infection, lymphocyte transformation test (LTT), cytokine detection in ELISpot assays, and granulysin (Grl) in flow cytometry. Treatment is based on a prompt drug discontinuation and mainly on the use of glucocorticoids.

CONCLUSION

Dealing with AED HRs is challenging. The primary goal in the diagnosis and management of HRs to AEDs should be trying to accurately identify the causal trigger and simultaneously identify a safe and effective alternative anticonvulsant. There is therefore an ongoing need to improve our knowledge of HS reactions due to AED medications and in particular to improve our diagnostic capabilities.

Severe cutaneous adverse drug reactions manifesting as Stevens-Johnson syndrome and toxic epidermal necrolysis reported to the national pharmacovigilance center in Nigeria: a database review from 2004 to 2017

Background:

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe cutaneous adverse reactions (SCARs). There is scant literature on the characteristics and causes of these conditions among the Nigerian population. Here, we describe the epidemiology, associated morbidity and mortality, and culpable drugs in SJS and TEN cases using the National Pharmacovigilance (NPC) database in Nigeria.

Methods:

A retrospective review of the NPC database was done to analyze SJS and TEN cases reported over a period of 14 years. Annual reports, age and sex of patients, type of reporter, suspects and concomitant drugs, time to onset (TTO) of the reactions, and outcome of SJS and TEN were evaluated.

Results:

The NPC received a total of 24,015 adverse drug reaction (ADR) reports. SJS and TEN accounted for 284 (0.1%) of the total reports, of which 254 (89.4%) were SJS and the remainder were TEN. Females (n = 184, 64.8%) and individuals aged 19–40 years (n = 181, 63.7%) were the most affected by SJS and TEN. Antiretrovirals, followed by antibiotics, were the most common drug classes reported to cause SJS and TEN, with nevirapine (n = 174, 40.7%) and co-trimoxazole (n = 143, 33.5%) being the most widely implicated drugs. Among patients with reported outcomes, 73 (28.7%) SJS and 3 (10.0%) TEN cases recovered without sequelae, at the time of reporting. Severity of the SCAR was reported for only 171 (69.0%) cases, of which 12 (4.7%) and 8 (26.7%) resulted in death (Grade 5) among SJS and TEN cases, respectively.

Conclusions:

Antiretroviral and antibiotics were the commonly reported offending group of drugs for SJS and TEN cases. Nevirapine and co-trimoxazole were the commonly reported suspect drugs. SJS and TEN were reported most frequently in females and in patients aged 19–40 years, indicating that drug surveillance and counseling in these groups of patients may be beneficial.

Erythema multiforme, Stevens Johnson syndrome, and toxic epidermal necrolysis reported after vaccination, 1999-2017

BACKGROUND

Since the last review of vaccine safety surveillance data for erythema multiforme (EM), Stevens Johnson syndrome (SJS), SJS/TEN, and toxic epidermal necrolysis (TEN) (EM/SJS/TEN), over 37 new vaccines have been introduced in the United States. We sought to describe reported EM/SJS/TEN after vaccines during 1999-2017.

METHODS

We identified U.S. reports of EM/SJS/TEN received by the Vaccine Adverse Event Reporting System (VAERS) during 1999-2017. We stratified analysis by condition (EM, SJS, or TEN), and analyzed reports by serious or non-serious status, sex, age group, time from vaccination to symptom onset, exposure to known causes of EM/SJS/TEN, and vaccines administered. We used Empirical Bayesian data mining to detect vaccine-AE pairs reported more frequently than expected.

RESULTS

Of 466,027 reports to VAERS during 1999-2017, we identified 984 reports of EM, 89 reports of SJS, 6 reports of SJS/TEN, and 7 reports of TEN. Few reports of EM (9%), and most reports of SJS (52%), SJS/TEN (100%), and TEN (100%) were serious. Overall, 55% of reports described males, 48% described children aged < 4 years; 58% of EM/SJS/TEN occurred ≤ 7 days after vaccination. Few reports (≤5%) described exposure to known causes of EM/SJS/TEN. Overall, childhood vaccines (e.g., combined measles, mumps, and rubella vaccine) were most commonly reported. We identified 6 deaths; 4 were exposed to medications associated with EM/SJS/TEN. EM after smallpox vaccine was reported disproportionately among people aged 19-49 years.

CONCLUSIONS

EM/SJS/TEN were rarely reported after vaccination; data mining identified a known association between EM and smallpox vaccine.

A review of cutaneous hypersensitivity reactions in infants: From common to concerning

Cutaneous hypersensitivity reactions in infants present in a variety of patterns. These skin eruptions can be dramatic, causing alarm in parents and medical personnel. Many of these syndromes have overlapping features, which adds to the confusion and uncertainty regarding diagnosis and management. This review discusses the spectrum of hypersensitivity responses with a focus on their presentation in infants. The clinical findings, pathophysiology, histopathology, management, and complications of these conditions will be reviewed.

Stevens-Johnson syndrome and toxic epidermal necrolysis with antiepileptic drugs: An analysis of the US Food and Drug Administration Adverse Event Reporting System

OBJECTIVE

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare and potentially fatal adverse skin reactions that are most commonly triggered by certain medications. One class of medications that has been highly associated with SJS/TEN reactions is antiepileptic drugs (AEDs). We sought to quantify the risk of SJS/TEN associated with AEDs as a class, as well as individual AEDs, in the United States.

METHODS

An analysis was performed of the US Food and Drug Administration Adverse Event Reporting System (FAERS) from July 2014 through December 2017. Rates of SJS/TEN were calculated for each AED compared with all other non-AEDs. Reporting odds ratios (RORs), proportional reporting ratios (PRRs), and 95% confidence intervals (CIs) were calculated using OpenEpi.

RESULTS

With 198 reports, AEDs had more reports of SJS/TEN than any other medication class. AEDs as a class had an ROR of 8.7 (95% CI 7.5-10.2) and a PRR of 8.7 (95% CI 7.5-10.2) compared with all other non-AEDs. The AEDs with the highest risk estimates were zonisamide (ROR 70.2, 95% CI 33.1-148.7; PRR 68.7, 95% CI 32.9-143.5), rufinamide (ROR 60.0, 95% CI 8.3-433.5; PRR 58.9, 95% CI 8.4-411.5), clorazepate (ROR 56.0, 95% CI 7.8-404.1; PRR 55.1, 95% CI 7.8-385.0), lamotrigine (ROR 53.0, 95% CI 43.2-64.9; PRR 52.2, 95% CI 42.7-63.7), phenytoin (ROR 26.3, 95% CI 15.5-44.7; PRR 26.1, 95% CI 15.4-44.2), and carbamazepine (ROR 24.5, 95% CI 16.0-37.5; PRR 24.3, 95% CI 16.0-37.1).

SIGNIFICANCE

Although AEDs as a class were associated with 9 times the risk of SJS/TEN compared with non-AEDs, there were 6 AEDs with risk estimates greater than 20. Increased awareness of this risk among both prescribers and patients, particularly variations in risk among different AEDs, along with education on early recognition of SJS/TEN signs/symptoms, may help mitigate the number and severity of these adverse events.

Influenza B virus infection and Stevens-Johnson syndrome

A 2-year-old boy with influenza B infection and rapidly worsening targetoid skin lesions with mucosal involvement was diagnosed with Stevens-Johnson syndrome (SJS) and treated with oseltamivir and intravenous immunoglobulin, with resolution of illness. Subsequent quadrivalent inactivated influenza vaccine was well tolerated. This case highlights the rarity of SJS in the setting of influenza B infection and addresses the safety of administering subsequent influenza vaccines to such individuals.

Is acetaminophen associated with a risk of Stevens-Johnson syndrome and toxic epidermal necrolysis? Analysis of the French Pharmacovigilance Database

AIM

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare but severe mostly drug-induced cutaneous reactions. Acetaminophen is an over-the-counter drug used worldwide to treat pain and reduce fever. In 2013, the US Food and Drug Administration informed the public that acetaminophen was associated with a rare risk of SJS/TEN. The aim of the present retrospective study was to analyse reports of acetaminophen as a possible suspect in the development of SJS/TEN from the French Pharmacovigilance Database (FPDB).

METHODS

Cases of TEN/SJS with acetaminophen as a suspect drug registered in the FPDB, collected from January 2002 to December 2013, were analysed by an expert group. The algorithm of drug causality for epidermal necrolysis (ALDEN) was used as a reference tool for SJS/TEN to assess the causality of each suspect drug.

RESULTS

After exclusion of 16 nonvalidated cases, 112 cases (47 TEN, 51 SJS, 14 SJS/TEN overlaps) involving 574 suspected drugs (5⋅1/case) were analysed. In 80 cases, the acetaminophen ALDEN score was inferior or equal to that of other drugs, associated with a higher suspicion for causality. In 32 cases, acetaminophen had the highest score but matched with a 'very unlikely' or 'unlikely' causality in 12 cases. For the 20 remaining cases with a 'possible' or ' probable' causality, a protopathic or a confounding bias was likely in 14 cases.

CONCLUSIONS

After analysis of the French pharmacovigilance data using the ALDEN algorithm, we found no obvious SJS/TEN risk related to the use of acetaminophen in this large national series.

Strengths, weaknesses and future challenges of biosimilars' development. An opinion on how to improve the knowledge and use of biosimilars in clinical practice

Biosimilars started receiving the marketing authorization by European Medicine Agency since 2006. The development of biosimilars follows a well-defined step-wise approach, the so-called comparability exercise, which aims to compare non-clinical (mainly quality features and biological activity) and clinical (efficacy and safety profiles) features of new biosimilars with their respective reference products. Despite the undeniable advantages of such procedure, some concerns (such as the absence of switching studies or the evaluation of efficacy and safety in all therapeutic indications) still exist about its. In particular, the European regulatory framework on biosimilars approval does not include the conduction of switching studies demonstrating the interchangeability to be carried out before marketing authorization. This is one of the main aspects that negatively affects healthcare professionals' clinical decisions on switch. In order to achieve a better knowledge on safety and efficacy of biosimilar drugs, real world data should be collected and post-marketing efficacy and safety clinical studies (including those evaluating specific endpoints, therapeutic regimens and patients population), should be planned. also the conduction of well-designed switching studies is highly advisable, especially in the case of biosimilar drugs used in oncology settings. Lastly, considering the critical role of antidrug antibodies on efficacy/safety profile of biologic drugs, studies based on therapeutic drug monitoring would be useful in order to achieve treatment optimization. Implementing the above strategies could be helpful to fill the gap in knowledge observed in the present European biosimilar regulatory framework.

Severe cutaneous adverse reactions to drugs

During the past decade, major advances have been made in the accurate diagnosis of severe cutaneous adverse reactions (SCARs) to drugs, management of their manifestations, and identification of their pathogenetic mechanisms and at-risk populations. Early recognition and diagnosis of SCARs are key in the identification of culprit drugs. SCARS are potentially life threatening, and associated with various clinical patterns and morbidity during the acute stage of Stevens-Johnson syndrome and toxic epidermal necrolysis, drug reactions with eosinophilia and systemic symptoms, and acute generalised exanthematous pustulosis. Early drug withdrawal is mandatory in all SCARs. Physicians' knowledge is essential to the improvement of diagnosis and management, and in the limitation and prevention of long-term sequelae. This Seminar provides the tools to help physicians in their clinical approach and investigations of SCARs.

Drug-induced Stevens-Johnson syndrome and toxic epidermal necrolysis in children: 20 years study in a tertiary care hospital

BACKGROUND

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe lifethreatening skin conditions. The most common cause of these manifestations is medications. Beside discontinued of the culprit drug, systemic corticosteroids were used as a primary treatment option among pediatric population. This study aimed to explore causative drugs (drug group/ latent period), treaments, complications, and treatment outcome (morbidity, mortality, length of hospital stay) of SJS and TEN in children.

METHODS

A retrospective chart was reviewed during the period of 1992 to 2012 at Srinagarind Hospital, Faculty of Medicine, Khon Kaen University, Thailand. SJS and TEN were clinically diagnosed and confirmed by pediatric dermatologists. Other possible causes other than druginduced SJS and TEN were excluded.

RESULTS

A total of 30 patients was recorded, including 24 (80%) SJS patients and 6 (20%) TEN patients. The mean age was 6.9 years (SD 4.4). Male to female ratio was 1.5:1. Antiepileptic drug group was the most common causative drug (n=18, 60%), followed by antibiotic drug group (n=8, 26.6%), and others (n=4, 13.3%) which included nonsteroidal antiinflammtory drugs (NSAIDs) and chemotherapy drugs. Systemic corticosteroids were used in 29 patients (96.6%). Intravenous immunoglobulin was used in one TEN patient (3.3%). There was a medium correlation between time to treatment (systemic corticosteroids) and the length of hospital stay (Spearman correlation coefficient=0.63, P=0.005). Two TEN patients (6.6%) died.

CONCLUSIONS

Carbamazepine was the most common causative drug of SJS and TEN in our study. The severity of skin detachment is not correlated to severity of ocular findings. However, the persistent of ocular complications up to one year is suggested for promptly appropriate ocular treatment in all SJS and TEN patients. Our data suggested that early administration of systemic corticosteroid may reduce the length of hospital stay and should be considered for the treatment of pediatric druginduced SJS and TEN.

The diagnosis and management of antibiotic allergy in children: Systematic review to inform a contemporary approach

BACKGROUND

Adverse drug reactions (ADRs) to antibiotics are commonly reported among children, with some representing genuine drug allergies. Accurate diagnostic tests are required. Drug provocation testing (DPT) is accepted as the gold standard investigation among children with suspected antibiotic allergy. We conducted this review to ascertain the strength of current evidence for using DPT as the first-line investigation for suspected antibiotic allergy among children.

METHODS

Medline was searched in June 2014 for publications investigating antibiotic allergy among children.

RESULTS

865 publications were retrieved and 76 studies selected. ADRs are most common among children of 0-4 years, however only some reveal drug allergies. The best evidence demonstrates that around 0.21% of general paediatric outpatients demonstrate positive antibiotic intradermal (ID) testing or DPTs, while 6.8% of children attending emergency departments for suspected β-lactam allergy may fulfil DPT reactions. Four studies used DPT-based protocols to investigate suspected antibiotic allergy, with two of these conducting ID testing and DPTs across all participants. β-lactam and clarithromycin ID testing had sensitivities of 66.7% and 75%, with positive predictive values of 36% and 33%, respectively, when compared with DPT data.

CONCLUSIONS

Our literature review found four (6%) publications that performed DPTs to subjects' index antibiotic across all participants. No rigorous evidence supports using skin prick, ID or in vitro diagnostic testing; indeed, the testing regimens, extracts and positivity criteria used are inconsistent. We recommend that suspected non-serious antibiotic allergy should be primarily investigated using DPT-based clinical protocols. Data examining their safety, acceptability and diagnostic performance are required.

Vaccine effectiveness against severe laboratory-confirmed influenza in children: results of two consecutive seasons in Italy

OBJECTIVE

To evaluate the effectiveness of seasonal influenza vaccine in preventing Emergency Department (ED) visits and hospitalisations for influenza like illness (ILI) in children.

METHODS

We conducted a test negative case-control study during the 2011-2012 and 2012-2013 influenza seasons. Eleven paediatric hospital/wards in seven Italian regions participated in the study. Consecutive children visiting the ED with an ILI, as diagnosed by the doctor according to the European Centre for Disease Control case definition, were eligible for the study. Data were collected from trained pharmacists/physicians by interviewing parents during the ED visit (or hospital admission) of their children. An influenza microbiological test (RT-PCR) was carried out in all children.

RESULTS

Seven-hundred and four children, from 6 months to 16 years of age, were enrolled: 262 children tested positive for one of the influenza viruses (cases) and 442 tested negative (controls). Cases were older than controls (median age 46 vs. 29 months), though with a similar prevalence of chronic conditions. Only 25 children (4%) were vaccinated in the study period. The overall age-adjusted vaccine effectiveness (VE) was 38% (95% confidence interval -52% to 75%). A higher VE was estimated for hospitalised children (53%; 95% confidence interval -45% to 85%).

DISCUSSION

This study supports the effectiveness of the seasonal influenza vaccine in preventing visits to the EDs and hospitalisations for ILI in children, although the estimates were not statistically significant and with wide confidence intervals. Future systematic reviews of available data will provide more robust evidence for recommending influenza vaccination in children.