Letter to the editor concerning the article 'Safety of vaccines administration in hereditary fructose intolerance'

Immunization coverage and timeliness of vaccination in young patients with inborn errors of metabolism: a French multicentric study

BACKGROUND

Inborn errors of metabolism (IEMs) are rare disorders that are heterogeneous in severity and clinical presentation. Patients with IEMs should receive the vaccination schedule recommended for the whole population, and specific vaccinations, such as the seasonal influenza vaccine, for the most vulnerable. The aim of this study was to evaluate vaccination coverage and timeliness in young patients with an IEM.

PATIENTS & METHODS

We conducted a retrospective multicentric (7 centers) study between February 2021 and May 2022 evaluating vaccination coverage and delays in French young patients with an IEM according to the yearly French vaccination schedules published since 2002. The results were analyzed considering patient health conditions as stable or at risk (defined as cardiorespiratory failure or by an IEM with a serious risk of metabolic crisis).

RESULTS

Two hundred seventy-five patients were enrolled in this study. Among them, only 164 (60%) were up-to-date with the standard French vaccination schedule, and 229 (83%) had received at least one vaccine from this schedule late. The rate of delayed vaccination was significantly greater in the at-risk group than in the stable group for the main primaries and first booster doses of the DTaP-IPV-Hib vaccine and for the first MMR injection. Finally, only 30 to 35% of at-risk patients were vaccinated against influenza during the three previous winters.

CONCLUSION

Young patients with an IEM had insufficient vaccination coverage with significant delays, exposing them to vaccine-preventable diseases, particularly at-risk patients with cardiorespiratory failure or a serious risk of metabolic crisis. Furthermore, only a few of the most vulnerable patients had received specific vaccinations, such as the influenza vaccine. Therefore, optimizing vaccination within the recommended schedule is crucial for this population of vulnerable children who have regular hospital follow-up.

Hypoglycemia in Children: Major Endocrine-Metabolic Causes and Novel Therapeutic Perspectives

Hypoglycemia is due to defects in the metabolic systems involved in the transition from the fed to the fasting state or in the hormone control of these systems. In children, hypoglycemia is considered a metabolic-endocrine emergency, because it may lead to brain injury, permanent neurological sequelae and, in rare cases, death. Symptoms are nonspecific, particularly in infants and young children. Diagnosis is based on laboratory investigations during a hypoglycemic event, but it may also require biochemical tests between episodes, dynamic endocrine tests and molecular genetics. This narrative review presents the age-related definitions of hypoglycemia, its pathophysiology and main causes, and discusses the current diagnostic and modern therapeutic approaches.

Vaccination strategies for people living with inborn errors of metabolism in Brazil

OBJECTIVE

Through a literature review, make recommendations regarding immunizations in people living with Inborn Error of Metabolism (IEM) in Brazil, assess the possible impact on metabolic decompensations after immunization, and if this specific population may have an impaired immune response to vaccines.

SOURCE OF DATA

The MeSH Terms vaccination OR vaccine OR immunization associated with the term inborn error of metabolism AND recommendation were used in combination with search databases. Only articles published after 1990, in the languages English, Spanish, French or Portuguese, human-related were included.

SYNTHESIS OF DATA

A total of 44 articles were included to make the following recommendations. Individuals with IEMs need to be up to date with their immunizations. Regarding which vaccines should be offered, children and adults should follow the routine immunization schedules locally available, including the COVID-19 vaccines. The only exception is the rotavirus vaccine for hereditary fructose intolerance. The benefit of immunization outweighs the very low risk of metabolic decompensation. Since not all patients will have an adequate immune response, measuring antibody conversion and titers is recommended CONCLUSIONS: All patients should receive age-appropriate immunizations in their respective schedules without delays. The only situation when vaccination may be contraindicated is with oral rotavirus vaccine in hereditary fructose intolerance. Monitoring the levels of antibodies should be done to detect any immune dysfunction or the necessity for boosters. A personalized immunization schedule is ideal for patients with IEMs. The reference organizations could improve their recommendations to address all IEMs, not only some of them.

Hereditary fructose intolerance: A comprehensive review

Hereditary fructose intolerance (HFI) is a rare autosomal recessive inherited disorder that occurs due to the mutation of enzyme aldolase B located on chromosome 9q22.3. A fructose load leads to the rapid accumulation of fructose 1-phosphate and manifests with its downstream effects. Most commonly children are affected with gastrointestinal symptoms, feeding issues, aversion to sweets and hypoglycemia. Liver manifestations include an asymptomatic increase of transaminases, steatohepatitis and rarely liver failure. Renal involvement usually occurs in the form of proximal renal tubular acidosis and may lead to chronic renal insufficiency. For confirmation, a genetic test is favored over the measurement of aldolase B activity in the liver biopsy specimen. The crux of HFI management lies in the absolute avoidance of foods containing fructose, sucrose, and sorbitol (FSS). There are many dilemmas regarding tolerance, dietary restriction and occurrence of steatohepatitis. Patients with HFI who adhere strictly to FSS free diet have an excellent prognosis with a normal lifespan. This review attempts to increase awareness and provide a comprehensive review of this rare but treatable disorder.