As claimed in the US, the chickenpox vaccination in childhood Its incidence does not increase in adulthood. And why is this? Well, because, according to the Spanish Ministry of Health, it's the opposite, which is why the chickenpox vaccine was discontinued at certain times—and left many of us with our children's vaccinations half-done, by the way, after having spent a good amount of money. In this regard, a population-based North American study published in Pediatrics and conducted at Kaiser Permanente Northern California (KPNC), demonstrated that mass vaccination in childhood does not cause more incidence of the virus in adulthood and, in addition, reduces hospital admissions in a sustained manner.
The Ministry of Health claims that, although the vaccination of children has demonstrated high efficacy in the child and adolescent population, they believe that it does not ensure total immunity in adulthood, when the disease becomes much more complicated and virulent. The Spanish Primary Care Network has supported these theses. It argues that the disease usually progresses in a benign in children and that infection in these cases confers a much higher immunity than vaccination. Furthermore, supporters of later immunization point out that neighboring countries such as Belgium, France, Denmark, the Netherlands, and Iceland do not recommend chickenpox vaccination at any age, except risk groups.
After more than a decade of widespread use, a trend has been observed in the United States very significant reduction in incidence and hospitalizations. And it has done so without evidence of a shift in cases to older ages when vaccination coverage remain high.
"In all this time, the disease has practically been eradicated and, however, an increase in infections has not been observed in the adult population, neither chickenpox nor shingles in the United States", says the coordinator of the vaccine committee of the Spanish Association of Pediatrics, David Moreno.
What does the WHO recommend?
La World Health Organization (WHO) highlights that, although it is not a priority health problem in all contexts, if the vaccine is safe and effective, mass vaccination can be considered an ideal strategy to reduce the burden of disease. However, he explains that more information is needed on the duration of protection and their behavior in adulthood to definitively position themselves in favor of universal immunization in all countries. What was striking in Spain was that the vaccine—which was neither mandatory nor free—was not always available, which generated inequalities.
“The probability that all children will contract chickenpox, coupled with a socioeconomic structure that implies high indirect costs for each case, makes chickenpox relatively important in industrialized countries with temperate climates. Routine childhood vaccination against this disease is estimated to be cost-effective in these areas ”, assures the WHO in a statement.
WHO does not currently recommend the inclusion of chickenpox vaccination in routine immunization programs for children. developing countries with other health priorities. However, it does provide that parents who wish to vaccinate their children can do so when the vaccine is available, especially if they are part of a vulnerable groups or live with people at risk.
- Most developing countries have other vaccine-preventable diseases that produce a morbidity and mortality considerably higher, so the systematic introduction of the chickenpox vaccine is not a priority.
- It can be raised routine childhood immunization against chickenpox in countries where the disease is a major public health and socioeconomic problem, the vaccine is affordable and a high level of quality can be achieved. high coverage (85%-90%) and sustained. With lower coverage there is a risk of modify the epidemiology and increase severe cases in older children and adults.
- In addition, the vaccine can be offered to teens and adults without a history of chickenpox, especially those at higher risk of contracting or spreading the infection. This use does not change children's exposure to the varicella-zoster virus.
Accumulating evidence on its impact on adulthood
Surveillance systems of countries with universal programs They point out that, after the introduction of the vaccine in childhood, the incidence of chickenpox decreases in all age groups, including the adolescent population. The most marked declines are observed when coverage exceeds high thresholds and is maintained over time.
Furthermore, the hospital load associated with chickenpox and its complications is significantly reduced, avoiding pneumonia, bacterial superinfections and encephalitisThis fall has been reinforced by the passage of one dose to two doses, a strategy that reduces outbreaks and chickenpox in vaccinated people (breakthrough).
Spain, with the progressive introduction and subsequent expansion of vaccination in childhood, has observed a reduction greater than 80% in the incidence in territories with wide and early adoption, with evidence of indirect protection in unvaccinated individuals. This pattern supports that childhood immunization reduces viral circulation and protects vulnerable people (cancer patients, transplant patients or immunosuppressed patients).
The key to not displacing the disease to older ages is none other than sustained coverageWhen this remains high, the risk of increasing cases in adults does not materializeHowever, low or irregular coverage can delay the age of infection among unvaccinated individuals and increase complications.
Effectiveness, guidelines and coverage to maintain
With a pattern of 2 doses in childhood (first around the second year of life and a second in the preschool stage), the effectiveness against forms moderate and severe It is very high and protection against any clinical form improves significantly compared to the single-dose regimen.
The current recommendations Pediatric scientific societies in Spain indicate that two doses should be administered to all children, with the possibility of using the vaccine tetraviral combination (SRPV) for the second dose. In addition, it is recommended rescue vaccination with 2 doses to susceptible children, adolescents and adults who have not had the infection.
Chickenpox can occur in vaccinated people as modified chickenpox, habitually mild and with few lesions. This phenomenon is considerably reduced with the 2-dose regimen. The post-exposure prophylaxis vaccinating within 3–5 days after contact, a measure that prevents or attenuates the disease.
To avoid outbreaks and limit the circulation of the virus, it is essential to maintain coverage above the thresholds that guarantee group immunity. Administrations must strengthen the nominal registration of vaccinations and the opportunity capture in primary care and school health.
Safety, contraindications and clinical considerations
The chickenpox vaccine (live attenuated virus) is safe and well toleratedThe most common reactions are local pain, redness, or mild rash near the injection site and low-grade fever. Rarely, a generalized rash mild.
Contraindications: pregnancy, severe immunodeficiencies and severe allergy to vaccine components. Precautions: treatment with salicylates, recent use of blood products or coexistence of moderate or severe acute illnesses (in mild cases, vaccination can be given).
If a small rash appears after vaccination, there may be a low probability of transmission of the vaccine virus; it is recommended to avoid close contact with infants or immunosuppressed individuals until resolution. In the long term, the appearance of shingles After vaccination, it is less common than after natural infection and is usually milder.
Before signs of severe allergic reaction (hives, difficulty breathing, facial or throat swelling, severe dizziness) urgent attention should be sought. Suspected adverse events should be reported to the appropriate health systems. pharmacovigilance corresponding.
Socioeconomic impact and public health
Beyond the clinical, vaccination reduces direct costs (consultations, treatments, hospitalizations) and Indirect costs (caregiver sick leave). In contexts with a temperate climate and high attendance at childcare centers, the universal strategy is Management when high coverage is reached and maintained.
The lower circulation of the virus offers indirect protection to people who cannot be vaccinated and to high-risk patients. Maintain a epidemiological surveillance active allows to adjust policies, detect spikes and evaluate possible changes in the epidemiology of the shingles, which have not shown clear increases attributable to childhood vaccination in scenarios with high and stable coverage.
Quick answers for families
Can you get vaccinated if you have a mild cold? Yes, as long as there is no high fever or significant general discomfort. If in doubt, the professional will assess each situation.
What if I don't remember if my child had chickenpox? Your medical history may be reviewed or serology may be requested. If there is no evidence of immunity, complete the pattern of 2 doses.
Can shingles appear after the vaccine? It is possible but less frequent and milder than after natural infection. Today, there are specific vaccines against shingles for adults that reduce the risk.
What to do if there has been close contact? Vaccination in the 3–5 days subsequent measures may prevent or mitigate the disease. For high-risk cohabitants, authorities may consider other measures.
The experience accumulated in different countries and the reality observed in Spain point to the same place: with high and sustained coverage, childhood vaccination against chickenpox drastically reduces the incidence and complications without showing an increase in cases in adults. Adding two doses, reinforcing the mass surveillance and facilitate the equal access They allow us to protect the entire community and especially those who need it most.