[Travel vaccinations in rheumatic diseases : Specific considerations in children and adults]

Investigating Nonspecific Effects of the Live-Attenuated Japanese Encephalitis Vaccine on Lower Respiratory Tract Infections in Children Aged 25-35 Months: Retrospective Cohort Study

BACKGROUND

Live attenuated vaccines may be used to prevent nontargeted diseases such as lower respiratory tract infections (LRTIs) due to their nonspecific effects (NSEs).

OBJECTIVE

We aimed to analyze the NSEs of the Japanese encephalitis vaccine on pediatric LRTIs in children aged 25 months to 35 months.

METHODS

A retrospective cohort study was conducted by using a population-based electronic health record database in Zhejiang, China. Enrolled participants were children born from January 1, 2017, to December 31, 2017, and who were inoculated with the live-attenuated Japanese encephalitis vaccine (JE-L) or inactivated Japanese encephalitis vaccine (JE-I) as the most recent vaccine at 24 months of age. The study was carried out between January 1, 2019, and December 31, 2019. All inpatient and outpatient hospital visits for LRTIs among children aged 25 months to 35 months were recorded. The Andersen-Gill model was used to assess the NSEs of JE-L against LRTIs in children and compared with those of JE-I as the most recent vaccine.

RESULTS

A total of 810 children born in 2017 were enrolled, of whom 585 received JE-L (JE-L cohort) and 225 received JE-I (JE-I cohort) as their last vaccine. The JE-L cohort showed a reduced risk of LRTIs (adjusted hazard ratio [aHR] 0.537, 95% CI 0.416-0.693), including pneumonia (aHR 0.501, 95% CI 0.393-0.638) and acute bronchitis (aHR 0.525, 95% CI 0.396-0.698) at 25 months to 35 months of age. The NSEs provided by JE-L were especially pronounced in female children (aHR 0.305, 95% CI 0.198-0.469) and children without chronic diseases (aHR 0.553, 95% CI 0.420-0.729), without siblings (aHR 0.361, 95% CI 0.255-0.511), with more than 30 inpatient and outpatient hospital visits prior to 24 months of age (aHR 0.163, 95% CI 0.091-0.290), or with 5 to 10 inpatient and outpatient hospital visits due to infectious diseases prior to 24 months old (aHR 0.058, 95% CI 0.017-0.202).

CONCLUSIONS

Compared with JE-I, receiving JE-L as the most recent vaccine was associated with lower risk of inpatient and outpatient hospital visits for LRTIs among children aged 25 months to 35 months. The nature of NSEs induced by JE-L should be considered for policymakers and physicians when recommending JE vaccines to those at high risk of infection from the Japanese encephalitis virus.

[International travels with children]

International travels with children need special planning and preparation. Besides considering general aspects, such as the age of the child, physical fitness, pre-existing illnesses, type and extent of the journey, climatic conditions at the destination and previous travel experiences, it is important to discuss relevant travel-associated risks in the context of travel consulting. This includes extensive advice concerning mosquito protection and malaria prophylaxis and counselling and implementation of travel vaccinations. Depending on the situation of the family, an individualized travel concept can be prepared, creating the foundation for a possible problem-free international travel.

[Vaccinations in dermatology]

Vaccinations are among the most successful prophylactic measures in medicine. As they are applied to healthy subjects, regulatory steps before licensing of any vaccination are strictly based on clinically controlled studies as well as on registry data in the further course. The probability and relevance of adverse reactions to vaccinations have to be weighed against any harm through the respective natural infection as well as the vaccination-induced protection against infections. Intolerance reactions to vaccinations are far more suspected than proven and altogether rare. Among these, specific dermatoses like psoriasis, atopic dermatitis and lichen planus are found as well as allergic reactions and a number of more nonspecific skin symptoms. Apart from provocation or exacerbation of an underlying dermatological disease, various intolerance reactions may be encountered which are classically allergologic or anaphylactoid. People with chronic dermatoses, especially those on immunosuppressive and immunomodulatory therapy, should have all recommended standard vaccinations. Vaccinations should not be administered during acute skin manifestations and relevant comedication-especially if immunomodulatory or immunosuppressive-has be taken into account in the decision to vaccinate and to define the time point of any vaccination. Inactivated vaccines may be administered even during ongoing immunosuppressive therapy, but may result in decreased immunological reactions and protection to infection. Live vaccines should be avoided.