The impact of pneumococcal conjugate vaccine on the prevalence and severity of hospitalizations for pneumonia in children.

Pneumococcal conjugate vaccines (PCV) were introduced into the Israeli national immunization plan starting with the heptavalent PCV7 in 2009 and then PCV13 in the late 2010. The objective of this study was to determine the vaccines' impact on hospitalization rates for community-acquired pneumonia on the severity of the pneumonia episodes and upon pneumococcal serotype distribution. We retrospectively reviewed all children hospitalized in our institution with pneumonia, aged between 1 and 16 years, between the years 2006 and 2015. Demographic, clinical, and laboratory data between three time periods: pre-PCV, PCV7, and PCV13, were compared. During the study period, 1375 children were hospitalized with pneumonia. A gradual decline in hospitalization rates due to pneumonia was observed starting in 2006 in the pre-PCV period and continued until after the introduction of PCV13. A similar trend was observed in pneumonias with a culture positive for S. pneumoniae. Pleural effusion was observed in 24% of all pneumonias, and this percentage was stable throughout the study period. The average age at hospitalization increased during the study period, as did the average duration of hospital stay. Pneumococcal serotypes included in the vaccine were isolated less frequently during the study and non-vaccine serotypes tended to appear more frequently. Pediatric pneumonia hospitalization rates continued to decline since the introduction of PCV without increasing the frequency of complications. Pneumococcal serotype distribution shifted in parallel. Our findings confirm the efficacy of PCV and support the evidence to include more serotypes in the next generation of PCV.

Being overweight and born in the spring are associated with an increased risk for rhinitis.

AIM: To explore the relationship between the season of birth and the prevalence of recurrent or chronic rhinitis (rhinitis). METHODS: The medical records of consecutive 17-year-old conscripts to the Israeli army were reviewed. We compared the prevalence of rhinitis between children born during different seasons. Multivariate analysis was performed with additional variables. RESULTS: The prevalence of rhinitis among the 1.1 million recruits was 7.1% in males and 5.3% in females. The association between birth season and the prevalence of rhinitis was highly significant (p < 0.001 for both genders). Spring was the birth season with the highest prevalence of rhinitis (7.4% in males and 5.5% in females). Males born in the winter and females born in the autumn had the lowest prevalence of rhinitis (6.7%, and 5.2% respectively). There was an increased odds ratio for rhinitis among those with a body mass index above 25, higher cognitive score and maternal birth country out of Israel or Africa. CONCLUSIONS: There was an increased risk of rhinitis among young Israeli adults who were born in the spring, were overweight and had a higher cognitive-score. Family planning to avoid a spring birth and preventing overweight may reduce the risk of chronic rhinitis.

Dual bronchodilation with tiotropium/olodaterol further reduces activity-related breathlessness versus tiotropium alone in COPD.

The 3-min constant speed shuttle test (CSST) was used to examine the effect of tiotropium/olodaterol compared with tiotropium at reducing activity-related breathlessness in patients with chronic obstructive pulmonary disease (COPD).This was a randomised, double-blind, two-period crossover study including COPD patients with moderate to severe pulmonary impairment, lung hyperinflation at rest and a Mahler Baseline Dyspnoea Index <8. Patients received 6 weeks of tiotropium/olodaterol 5/5 µg and tiotropium 5 µg in a randomised order with a 3-week washout period. The speed for the 3-min CSST was determined for each patient such that an intensity of breathing discomfort ≥4 ("somewhat severe") on the modified Borg scale was reached at the end of a completed 3-min CSST.After 6 weeks, there was a decrease in the intensity of breathlessness (Borg dyspnoea score) at the end of the 3-min CSST from baseline with both tiotropium (mean -0.968, 95% CI -1.238- -0.698; n=100) and tiotropium/olodaterol (mean -1.325, 95% CI -1.594- -1.056; n=101). The decrease in breathlessness was statistically significantly greater with tiotropium/olodaterol versus tiotropium (treatment difference -0.357, 95% CI -0.661- -0.053; p=0.0217).Tiotropium/olodaterol reduced activity-related breathlessness more than tiotropium in dyspnoeic patients with moderate to severe COPD exhibiting lung hyperinflation.

The influence of reducing fever on blood oxygen saturation in children.

Laboratory-based studies on the oxyhemoglobin dissociation curve (ODC) suggest that high blood temperature decreases the affinity of hemoglobin for oxygen. The aim of the study was to evaluate the influence of pyrexia on oxygen saturation (SpO2) in children presenting to the emergency department. Normoxemic children with body temperature at or above 38.5 °C were included. Patients with a dynamic respiratory disease were excluded. SpO2 was measured before and after antipyretic treatment. The changes in body temperature and SpO2 were assessed and compared to the changes predicted from the ODC. Thirty-four children completed the study. Mean temperature at presentation was 39.17 ± 0.549 °C and mean SpO2 was 96.15 ± 2.21%. The mean decrease in temperature after antipyretic treatment was 1.71 ± 0.67 °C and mean increase in SpO2 was 0.95 ± 1.76%. Among children in whom pyrexia decreased by 1.5 °C or more, the mean increase in SpO2 was 1.45 ± 1.57%. The measured increase in SpO2 was close to the increase anticipated from the ODC. CONCLUSION: Pyrexia was associated with decreased SpO2 in normoxemic children. The influence of pyrexia in children with low-normal oxygen saturation is expected to be much higher because of the non-linear shape of the ODC. Physicians treating patients with fever should be aware of this effect, especially in patients with borderline hypoxia. What is Known: • High blood temperature decreases the affinity of oxygen to hemoglobin. • It is not known whether fever would decrease SpO 2 . What is New: • Fever is associated with decreased SpO 2 .

Is obstructive sleep apnea syndrome in children season dependent?

INTRODUCTION: The most common cause of obstructive sleep apnea (OSA) in children is an enlargement of tonsils and/or adenoids. Previous studies have shown that the size of adenoids and tonsils is influenced by upper respiratory tract infections and exposure to allergens. The rate of exposure to bacteria, viruses, and allergens fluctuates from season to season. Therefore, we hypothesized that the rate of polysomnograms positive for OSA may vary according to season. OBJECTIVE: The objective of this study is to determine whether the prevalence of OSA in children, as determined by polysomnography, is affected by the season during which the study was performed. METHODS: We retrospectively reviewed polysomnography tests of 296 children, ages 0-12 years, referred for suspected OSA. We compared the Obstructive Apnea Hypopnea Index (OAHI) between the seasons and the rates of abnormal tests in each season according to the degree of severity. RESULTS: The mean OAHI did not significantly differ among the seasons (winter, 3.0 ± 5.0; spring, 3.0 ± 4.9; summer, 4.0 ± 6.3; fall, 3.4 ± 5.7, p = 0.183). When dividing the OAHI by levels of severity, no seasonality was found in moderate (winter, 13.8 %; spring, 6.7 %; summer, 11.7 %; fall, 14.1 %, p = NS) and severe OSA (winter, 8.8 %; spring, 11.2 %; summer, 10 %; fall, 7.8 %, p = NS). There was a small increase in the frequency of mild OSA diagnoses in the summer compared to the other seasons. CONCLUSION: In this study, season does not appear to affect the rate of diagnosis of significant OSA in children. Re-evaluation during a different season is unlikely to provide different results and may postpone surgery unnecessarily.

[The effect of fever on blood oxygen saturation in children].

INTRODUCTION: Blood temperature is inversely correlated with oxygen-hemoglobin affinity as demonstrated by in-vitro oxyhemoglobin dissociation curve (ODC) experimentation. OBJECTIVE: To evaluate the real-life effect of fever on blood oxygen saturation (SO2) in children. METHODS: Children treated in the Pediatric Emergency Department at the "Shaare Zedek" Medical Center with a body temperature > 38.50C were included in the study. Children suffering from active lung disease were excluded. The following parameters were collected before and 90 minutes after administering antipyretic therapy: temperature, SO2, respiratory rate and pulse rate. RESULTS: Twenty-two subjects completed the study. The mean decrease in temperature was 2.030C. Following the decrease in body temperature, a rise in SO2 was noted in 17 subjects (77.3%). The mean SO2 before the antipyretic therapy was 96.18%. The mean SO2 after the drug administration was 97.73%. The average rise in SO2 was 1.55 ± 1.79% (p = 0.001). CONCLUSIONS: Fever in children is associated with decreased SO2. This decrease is not clinically significant in patients with normal baseline SO2. Calculation reveals that in patients with baseline SO2 close to the steep region of the ODC, the same increase of body temperature will cause a significantly greater decrease in SO2. In patients with a baseline SO2 of 91% at body temperature of 370.00C, an increase in body temperature to 400.00C is anticipated to cause a 5% decrease in SO2. This decrease has major potential implications concerning treatment decisions.

Methacholine challenge test results in children are season dependent.

BACKGROUND: It is known that several parameters influence the positivity of a methacholine challenge (MCH), including a recent viral disease, allergies, and air pollution. Reports regarding the influence of the season upon the positivity of MCH are scarce. The aim of this study was to assess the percentage of positive MCH tests per season. METHODS: We retrospectively evaluated all MCH tests performed in children and adults in a single center over a 30-month period. The percentage of positive tests for summer was compared with that of other seasons. RESULTS: A total of 155 challenges were performed in children (under 20 years old) and 527 in adults. Thirty-eight percent of the tests were positive in adults and 71 % in children. The percentage of positive tests in the summer was significantly lower than the percentage of positive results during the rest of the year in children (58.5 vs. 75.4 %, respectively; p = 0.046). By contrast, there was no difference between the seasons in adults (39 vs. 38 %, respectively; p = 0.92). CONCLUSIONS: There is a difference of 22.4 % in the percentage of positive tests in the summer months compared to the rest of the year in children, suggesting a reduction in the sensitivity of the MCH test in the hot season. We suggest that in cases where asthma is strongly suspected in a child and the MCH test was negative in the summer, one should consider repeating the MCH test in another season.

Ultrasound velocity through the tibia is not affected by prolonged inhaled steroid therapy in children.

AIM: To evaluate in a prospective, cross-sectional cohort study the impact of inhaled corticosteroids (ICS) on bone speed of sound (SOS) in asthmatic children. METHODS: Children with mild-to-moderate asthma from a pulmonary clinic were assessed over a 2-month period. We recorded clinical and demographic data related to asthma severity, its treatment, participation in sports and dairy intake. Tibial SOS was measured using the Sunlight Omnisense 7000S quantitative ultrasound bone sonometer. RESULTS: Eighty-five mild-to-moderate asthmatic children were studied. Age range was 1.4-17 years (71.7% boys). Average disease duration was approximately 5 years, and the average cumulative duration of ICS therapy was approximately 1.5 years. Average SOS Z-score was slightly negative and varied between -3.5 and +1.9 SD. In univariate analysis, SOS Z-score was negatively correlated with asthma duration (R(2) = 5.7%, p = 0.028) and ICS duration (R(2) = 4.9%, p = 0.042). In backward stepwise multiple regression, where SOS Z-score was the dependent variable, the only variables that remained significant in the final analysis were gender (p = 0.015), asthma duration (p = 0.003) and BMI (p = 0.048) (R(2) for the model 17.52% p = 0.01). CONCLUSION: Prolonged inhaled steroid therapy appears to have no deleterious effect upon SOS in children with mild-to-moderate persistent asthma.

Asthma and hemoglobinopathy: when is supplemental oxygen required?

Asthma is the most common reason for referral to the emergency department in childhood. In severe attacks, supplemental O2 is given when oxygen saturation level is <90%. Described herein is the case of a child with persistent low oxygen saturation as measured on pulse oximetry (S(p)O2) after full clinical recovery from an asthma attack. Simultaneously, P(a)O2 was normal. A diagnosis of abnormal hemoglobin with decreased oxygen affinity (hemoglobin Seattle) was made on hemoglobin electrophoresis and genetic analysis. To ascertain when supplemental oxygen was needed, an oxygen dissociation curve was plotted using the tonometer technique, and it was found that an S(p)O2 of 70% is parallel to a P(a)O2 of 60 mmHg. Plotting an oxygen dissociation curve is a simple reproducible method to determine when supplemental oxygen is required for a child with a hemoglobinopathy.

Effect of moderate elevation above sea level on blood oxygen saturation in healthy young adults.

BACKGROUND: Arterial hemoglobin oxygen saturation (SaO2) decreases at an altitude of >1,500 m. There are no reports on normal SaO2 at altitudes between 0 and 1,500 m. The clinical significance of decreased SaO2 at such altitudes is unclear. OBJECTIVE: To test the hypothesis that in healthy volunteers normal SaO2 at moderate altitude (MA; 725 m) is lower than that at almost sea level (SL; 43 m). METHODS: SaO2 was measured by transcutaneous pulse oximetry in young healthy volunteers at MA and was compared to equivalent measurements at SL. In addition, a 6-min walk test was performed and SaO2 at the end of the walk was compared between the two locations. RESULTS: 111 males were checked at MA and 101 at SL. At rest, nadir SaO2 was 95% at MA compared to 97% at SL. Mean SaO2 at rest was slightly higher at SL (98.53 ± 0.52) compared to MA (98.11 ± 0.8; p < 0.01). In subjects who completed the 6-min walk test, SaO2 slightly decreased after the test in both locations, by 0.38 ± 0.65% in the SL group and by 0.37 ± 1.12% in the MA group. This difference is not statistically significant by univariate analysis; however, a multiple regression analysis indicated that the drop in SaO2 was higher at MA than at low altitude. CONCLUSIONS: We found a low but significant difference in SaO2 between near-SL and at an altitude of 725 m. The clinical significance of this difference, in terms of human health, is probably minimal.

Seasonal effect on exercise challenge tests for the diagnosis of exercise-induced bronchoconstriction.

Exercise challenge test (ECT) may help in the diagnosis of asthma. Asthma is season dependent (relative summer nadir).This study was designed to prospectively show that ECT sensitivity decreases when performed in summer and/or out of personal asthma season. We performed two ECTs in 49 patients with suspected asthma, at baseline and at least 6 months later. Test positivity was defined as a ≥10% drop of forced expiratory volume in 1 second after exercise. Patients were defined as having exercise-induced bronchoconstriction (EIB) if at least one of the two tests was positive. We analyzed the impact of season and of patient-reported asthma season on ECT sensitivity. We performed 21 ECTs in the summer and 77 in other seasons. Summer tests were positive in 14.3% of patients versus 33.8% in other seasons (p = 0.11). In patients with confirmed EIB, the sensitivity (95% CI) of a summer test was 0.25 (0.007-0.57), compared with 0.76 (0.58-0.89) in other seasons. Tests performed out of personal asthma season were positive in 10.0% of tests compared with 37.1% of tests during personal asthma season (p = 0.007). In patients with confirmed EIB, the sensitivity (95% CI) of a test performed out of asthma season was 0.27 (0.07-0.61), compared with 0.74 (0.55-0.87) during season. The sensitivity of ECT performed in the summer or outside of the personal asthma season is about one-third of ECT performed not in the summer or during personal asthma season. We suggest performing ECTs during personal asthma season and not in the summer if there is no asthma season known.

Factors associated with resolution of childhood asthma by the age of 17: Large cohort analysis.

BACKGROUND: Many children with asthma will become asymptomatic during adolescence. In this study, we evaluated factors associated with recovery from asthma by the age of 17. METHODS: The medical records of 17-year-old conscripts to the Israeli army with asthma were compared with the records of conscripts with rigorously diagnosed resolved asthma. We assessed the association between the following parameters and asthma resolution: body mass index (BMI), recurrent rhinitis, birth season, socioeconomic level, and cognition. RESULTS: Sixty-eight thousand and ninety conscripts with active asthma were compared to 14,695 with resolved asthma. In univariate analysis, rhinitis, overweight, underweight, higher socioeconomic level, and lower cognitive score were associated with active asthma (p < 0.001 for both sexes), but not the season of birth. In multivariate analysis, only overweight, underweight, rhinitis, and lower cognitive score (p < 0.001 for both sexes) remained significantly associated with persistence of asthma. CONCLUSIONS: Although association does not prove causation, our finding is another reason to encourage adolescents with asthma to maintain a normal body weight. Prospective interventional studies are needed in order to decide whether changing weight to ensure BMI is within the ideal range and controlling rhinitis increases the odds of resolution of asthma in adolescence.

Unilateral lung intubation for pulmonary air leak syndrome in neonates: a case series and a review of the literature.

Air leak syndrome represents a common set of complications of ventilated premature neonates and includes pneumothorax, pneumomediastinum, pulmonary interstitial emphysema, and pneumatocele. Unilateral intubation is an infrequently utilized treatment option. We report our experience of three cases of air leak syndrome in neonates, each treated with unilateral intubation, including two cases of recalcitrant pneumothorax. A review of the literature of similar neonatal cases is presented. In view of our experience and the review of the literature, we suggest that unilateral intubation is an efficient and relatively safe therapy in cases of neonatal air leak syndrome. It is also suggested that appropriate treatment duration should be at least 48 hours.

Infants' Sleep: Israeli Parents' Knowledge, Attitudes and Practices.

The purpose of the study was to assess Israeli parents' knowledge of and attitudes towards practices promoting infants' safe sleep and their compliance with such practices. Researchers visited the homes of 335 parents in 59 different residential locations in Israel and collected their responses to structured questionnaires. SPSS 25 statistical package for data analysis was used. Attitude scales were created after the reliability tests and scaled means of parental attitudes were compared between independent groups differentiated by gender, ethnicity, and parental experience. A logistic regression was run to predict the outcome variable of babies' sleep positions. The total knowledge score was significantly higher for women (56.3%) than for men (28.6%; p < 0.001). Arabs were more committed to following recommendations (29.3%) than Jews (26.9%; p < 0.001). Consistent with safe sleep recommendations, 92% of the sampled parents reported avoiding bedsharing and 89% reported using a firm mattress and fitted sheets. The risk of not placing a baby to sleep in a supine position was higher among older parents (adjusted odds ratio-AOR = 0.36, 95%CI 0.16-0.82), smoking fathers (AOR = 2.66, 95%CI 1.12-6.33), parents who did not trust recommendations (AOR = 4.03, 95%CI 1.84-8.84), parents not committed to following recommendations (AOR = 2.83, 95%CI 1.21-6.60), and parents whose baby slept in their room (AOR = 0.38, 95%CI 0.17-0.88). Knowledge of safe sleep recommendations was not associated with actual parental practices. Trust of and commitment to recommendations were positively correlated with safe sleep position practices. It is essential to develop ethnic-/gender-focused intervention programs.

Are there gender differences in blood oxygen saturation in prepubertal children?

INTRODUCTION: Previous studies reported higher oxygen saturation (SpO2 ) in healthy young adult females as compared to males. The objective of the current study was to evaluate whether or not similar differences exist in prepubertal children. METHODS: SpO2 levels, respiratory rate, and pulse were measured in 4- to 10-year-old males and females. Anthropometric variables, including ethnic origin, age, height, weight, BMI (Body Mass Index), BSA (Body Surface Area), barometric pressure, and altitude above sea level were collected as well. RESULTS: Ninety five males and 93 females participated in the study. Groups were similar, in terms of respiratory rate, pulse, and anthropometric variables. Mean SpO2 in males was 96.95 ± 1.09%, similar to SpO2 in females measuring 96.85 ± 0.98%, P = .52. CONCLUSION: In contrast to young adults, there is no gender-related difference in mean oxygen saturation in prepubertal healthy children. It is likely that this difference is due to variations in age-related sex hormones. Further studies are needed to explore the mechanism explaining why prepubertal children do not show gender-specific differences in oxygen saturation in contrast to adults.

N-terminal pro-B-type natriuretic peptide as a marker of bronchopulmonary dysplasia in premature infants.

We performed an observational pilot study of plasma concentrations of N-terminal pro-B-type natriuretic peptide (BNP) in premature infants with a diagnosis of bronchopulmonary dysplasia (BPD) at 4 weeks of age and after 1 month of conventional therapy. Thirty-four premature infants born before 34 weeks' gestational age without cardiac or infectious diseases were included. Serum NT-pro-BNP was measured in all neonates at 4 weeks of age. In infants with the diagnosis of BPD (n = 11), measurements were repeated at 6 and 8 weeks of age under conventional treatment. Specific clinical characteristics were collected prospectively. Baseline NT-pro-BNP concentrations were high in healthy premature infants compared with previously reported healthy neonates, and significantly higher in those who developed BPD. There was a significant correlation between concentrations of NT-pro-BNP and severity of respiratory distress as assessed by several methods. The concentrations of NT-pro-BNP decreased significantly over time in BPD infants. Premature infants have high concentrations of NT-pro-BNP at 1 month of age. NT-pro-BNP concentrations are significantly higher in BPD infants and decline over time. NT-pro-BNP concentrations correlate with clinical severity of respiratory disease.

Ibuprofen does not prevent postbronchoscopy fever in children undergoing broncho-alveolar lavage.

BACKGROUND: Fiber-optic bronchoscopy (FOB) of the lower airways is a routine examination performed for investigating varying respiratory complaints in children. A common side effect is a transient high fever on the day of the FOB. Such episodes are usually unrelated to an infectious process but may cause clinical uncertainty and parental anxiety. We have previously shown that a single dose of systemic dexamethasone significantly reduces the rate of fever postbronchoscopy (FPB). RESEARCH QUESTION: To prospectively analyze the effect of a prophylactic dose of ibuprofen upon the FPB. STUDY DESIGN AND METHODS: Children presenting for elective FOB and broncho-alveolar lavage (BAL) were randomized, in a double-blind fashion, to receive a single dose of ibuprofen syrup 10 mg/kg or placebo prior to the procedure. Parents were contacted the next day to record the presence or absence of fever. RESULTS: Sixty-one children were included in the final analysis. Thirty-one children were in the treatment group and 30 in the placebo group. FPB occurred in 40 children (65%). There was no difference in the rate of FPB between placebo (63%) and treatment (67%) groups (P = .717). Fifty (82%) children had a positive BAL culture. Among them, 38 had FPB (76%) compared with only 2 of 11 (18%) of those with negative culture (P = .00026, relative risk 4.18). About 80% of positive cultures grew Haemophilus influenza. There was no significant difference between the number of BALs with a positive culture between the treatment and placebo groups (87% vs 77%, P = .35). CONCLUSION: FPB occurs in around twothirds of children when BAL is performed. Fever occurred significantly more frequently when BAL culture is positive. A single standard dose of the nonsteroidal anti-inflammatory drug ibuprofen administered before a FOB does not prevent FPB.

Supraglottoplasty for severe laryngomalacia. Can we predict success?

OBJECTIVES: Laryngomalacia is the dynamic collapse of supraglottic structures during inspiration, leading to a variable degree of airway obstruction. Clinical symptoms appear in the first months of life and are usually mild and resolve by the age of 12-18 months. In severe cases, surgical intervention may be considered. The goal of the study was to review the clinical outcome of pediatric patients who underwent supraglottoplasty for laryngomalacia. MATERIAL AND METHODS: Clinical and demographic data were retrieved from medical records of children diagnosed with laryngomalacia by laryngo-bronchoscopy between 2013 and 2019. Indications, outcome and long-term follow-up were collected from children undergoing surgery. RESULTS: During the study period, 115 children were diagnosed with laryngomalacia. The median age at diagnosis was 3 months. Synchronous airway lesions were diagnosed in 20% of patients. Ten (8.7%) children underwent surgical treatment because of significant respiratory symptoms and/or failure to thrive. Three of them had comorbidities. All otherwise healthy children had significant respiratory and nutritional improvement after surgery while those with comorbidities had less successful outcomes. CONCLUSION: We conclude that in severe cases of laryngomalacia, supraglottoplasty has an important role to play in management. In children with comorbidities, the surgical results may be less successful. Therefore, we recommend that the decision to operate should be individualized, ensuring full disclosure to the family regarding the probable benefit along with the limitations of surgery.

Does birth season influence the odds for asthma? Large cohort analysis.

BACKGROUND AND OBJECTIVE: Few studies have examined the possibility of a link between birth season and the risk for asthma. Those studies that mainly focused on young children, reached different conclusions regarding both the existence of such a link and the season with the highest risk. The purpose of this study was to reinvestigate the relationship between birth season and asthma in a very large cohort, larger than in all previous studies, focusing on adolescents. METHODS: The medical records of consecutive 17-year-old conscripts, born between 1978 and 1999, undergoing medical evaluation before their military service, were reviewed. The prevalence of asthma among conscripts was calculated according to the season of birth. RESULTS: Data from 6 26 460 males and 4 54 104 females were collected. Asthma prevalence was 6.6% of the males and 5.8% of the females. Asthma prevalence was highest among those born in the summer and was approximately 9% higher in women and 6% higher in men than those born in the winter. Those born in the winter had the lowest prevalence of asthma. June was the birth month with the highest prevalence of asthma in both genders together with September among males. CONCLUSIONS: Being born in the summer, especially in June, is associated with an increased risk of asthma compared with a winter birth among Israeli army conscripts. Further research is required to determine the impact of the season of birth on the risk of asthma in higher risk populations.