Opinions, attitudes, and barriers to pediatric vaccination in Argentina.

In Argentina, vaccines included in the national calendar are mandatory, free of charge, and access to vaccination services with social equity for all stages of life are guaranteed by law. However, vaccination coverages are still suboptimal and have shown a constant decrease in the last five years. This study aimed to perform a survey to describe the parent's confidence, risk perception, sources of information and access barriers to vaccines and vaccination in Argentina. A survey was designed for parents in charge of children under 12 years of age to answer. The questionnaire was constructed based on validated questions of the international peer-reviewed literature adapted to our country's characteristics. The survey was performed on 1,202 respondents, covering all regions of Argentina, between 19th May and 18th June 2020. To highlight, 76.6 % were female and the mean age was 40.72 (±9.36 years). 9 % participants reported to assist to the private vaccination center, while 64 % and 23 % referred to take their children to the public vaccination point (primary care center and hospital, respectively). Additionally, respondents agreed that vaccines are safe (92 %), effective (94 %), and important for children to receive them (98 %). 48 % could identify-one or more barriers to vaccination, access and affordability were the most reported ones (74 %) being the lack of vaccine the main reason. In conclusion, this study showed that the great majority of parents trust in vaccines and health care teams but access and affordability reasons emerged as the main barriers to vaccination in our country.

Humoral and cellular immune memory response 12 years following single dose vaccination against hepatitis A in Argentinian children.

Infants' universal hepatitis A virus (HAV) single-dose vaccination has been highly effective for controlling HAV infection in Argentina, and in other Latin-American countries that adopted that strategy. Although antibodies wane over time, this has not been associated with HAV outbreaks or breakthrough infections, suggesting a relevant role for memory immunity. This study assessed long term humoral and cellular immune memory response after an average of 12 years follow-up of HAV single-dose vaccination. We selected 81 HAV-single dose vaccinated individuals from a 2015 study, including 54 with unprotective (UAL) and 27 with protective antibody levels (PAL) against HAV. Humoral memory response was assessed by measuring anti-HAV antibody titers at admission in both groups, and 30 days after a booster dose in the UAL group. Flow cytometry analysis of peripheral blood mononuclear cell samples stimulated with HAV antigen was performed in 47/81 individuals (21 with PAL, 26 with UAL) to identify activated CD4 + memory T cells or CD8 + memory T cells. The results showed that 48/52 (92%) individuals from UAL group who completed follow up reached protective levels after booster dose. In the PAL group, anti-HAV Abs waned in 2/27 (7%) individuals lacking seroprotection, while in 25/27 (93%) Abs remained >10 mUI/mL. HAV-specific memory CD4 + T cells were detected in 25/47 (53.2%) subjects while HAV-specific memory CD8 + T cells were observed in 16/47 (34.04%) individuals. HAV-specific memory CD4+ and CD8+ T cell responses were detected in 11/21 (52.4%) and in 9/21 (42.9%) subjects with PAL and in 14/26 (53.8%) and in 7/26 (26.9%) individuals with UAL, showing that the presence of memory T-cells was independent of the level or presence of anti-HAV antibodies. Long-term immunity demonstrated in the present work, including or not antibody persistence, suggests that individuals with waned Ab titers may still be protected and supports the single-dose HAV strategy.

Experiencia argentina en la etapa final de erradicación de la polio: cambio de vacuna oral trivalente a bivalente / Argentinian experience to finish polio eradication: switch from trivalent to bivalent oral poliovirus vaccine

Entre el 17 de abril y el 1 de mayo de 2016, 155 países en todo el mundo cambiaron el uso de la vacuna oral trivalente, que protege contra los tres tipos de poliovirus (1, 2 y 3), por la vacuna oral bivalente, que protege contra los poliovirus tipo 1 y 3. Este cambio señala el mayor esfuerzocoordinado globalmente en la historia de las vacunas. En Argentina se realizó el pasado 29 de abril, con una intensa planificación previa y una posterior validación.

Single-Dose Universal Hepatitis A Immunization in Argentina: Low Viral Circulation and High Persistence of Protective Antibodies Up to 4 Years.

BACKGROUND: Single-dose hepatitis A virus (HAV) vaccination was implemented in all Argentinean children aged 12 months in 2005. Between 2005 and 2011, a dramatic decline was observed in HAV infection rates, fulminant hepatitis, and liver transplantation. This study assessed current viral circulation and estimated protective antibody persistence 4 years after vaccination. METHODS: Prevalence of prevaccination anti-HAV antibodies in 12-month-old children was evaluated as an indirect estimation of viral circulation (Group A). Seroprevalence was also measured in 5-year-old children who received 1 dose of HAV vaccine at 1 year of age (Group B). Blood samples were tested for immunoglobulin (Ig)G anti-HAV antibodies (seroprotection = ≥10 mIU/mL). All Group A-positive samples were tested for IgM anti-HAV antibodies to identify recent infections. Logistic regression analysis was done to evaluate associations between demographic and socioeconomic variables and seroprotection. RESULTS: Of 433 children from Group A, 29.5% (95% confidence interval [CI], 25.2-33.8) were positive for IgG anti-HAV antibodies with a geometric mean concentration (GMC) of 6.17 mIU/mL (95% CI, 5.33-7.15 mIU/mL); all IgM anti-HAV were negative. From 1139 in Group B, 93% (95% CI, 91.7-94.6) maintained seroprotection with a GMC of 97.96 mIU/mL (95% CI, 89.21-107.57 mIU/mL). Kindergarten attendance was associated with seroprotection in Group B (odds ratio [OR], 2.0; 95% CI, 1.26-3.3). In contrast, high maternal educational level was associated with a lack of seroprotection in this group (OR, .26; 95% CI, .09-.8). CONCLUSIONS: Single-dose, universal hepatitis A immunization in infants resulted in low HAV circulation and persistent immunologic protection up to 4 years in Argentina. Variables associated with presence or absence of seroprotection in vaccinated children could be related to differences in hygiene habits in settings with residual viral circulation.

Maternal immunization in Argentina: A storyline from the prospective of a middle income country.

The importance of vaccination during pregnancy lies not only in directly protecting vaccinated women, but also by indirectly protecting small infants during the first few months of life. Vaccination against the flu and whooping cough is a priority within the comprehensive care strategy for pregnant women and small infants in Argentina, in the context of transitioning from child vaccination to family vaccination. In 2011, the flu vaccine was included in the National Immunization Schedule (NIS) as mandatory and free of charge, with the aim of decreasing complications and death due to influenza in the at-risk population in Argentina. The national vaccination coverage attained in pregnant women in the past 4 years (2011-2014) has been satisfactory; 88% coverage was attained in the year this program was introduced to the schedule. In the following years, coverage was maintained at greater than 95%. In February 2012, Argentina became the first country in Latin America to have universal vaccination strategy for pregnant women against whooping cough. This recommendation was implemented throughout the country by vaccination with the diphtheria toxoid, tetanus toxoid, and acellular pertussis (Tdap) vaccine starting at 20 weeks of pregnancy, with the aim of decreasing morbimortality due to whooping cough in infants under 6 months of age. The vaccine was incorporated into the NIS in 2014. More than 1,200,000 doses were applied in this period. Both vaccines showed a suitable safety profile and no serious events were reported. Argentina is an example of a middle-income country that has been able to implement a successful strategy for primary prevention through vaccines, making it a health policy.

Economic analysis of the single-dose immunization strategy against hepatitis A in Argentina.

BACKGROUND: Vaccination against hepatitis A (HA) was carried out only as part of a limited outbreak control strategy in Argentina until June 2005, when universal immunization in infants was introduced into the national immunization calendar. A single-dose strategy was chosen instead of the standard two-dose schedule used elsewhere. This study aimed to estimate preventive, medical, and non-medical costs related to HA and to compare these costs in the periods before and after mass vaccination. METHODS: A retrospective analysis estimated treatment costs of HA and unspecified hepatitis cases reported to the National Health Surveillance System from 2000 to 2010. Costs related to immunization, fulminant hepatitis (FH), liver transplantation, and death were projected as well. Using a social perspective and a healthcare system perspective, costs in two 5-year periods were compared: 2000-2004 versus 2006-2010. Finally, we evaluated the impact of different discount rates, FH risk, and exclusion of unspecified hepatitis cases in the sensitivity analysis. RESULTS: Total HA and unspecified hepatitis cases decreased from 157,871 in 2000-2004 to 17,784 in 2006-2010. Medical and non-medical costs decreased from US$11,811,600 and US$30,118,222 to US$1,252,694 and US$4,995,895 in those periods, respectively. Immunization costs increased from US$6,506,711 to US$40,912,132. Total preventive, medical, and non-medical costs decreased from US$48,436,534 to US$47,160,721, representing a 2.6% reduction in total costs between the two periods. When a healthcare system perspective was considered or unspecified hepatitis cases were excluded, total costs were 130.2% and 30.8% higher in 2006-2010 than in the previous period, respectively. CONCLUSION: After implementation of the universal single-dose vaccination against HA in infants in Argentina, an impressive decline was observed in HA cases, with a decrease in medical and non-medical costs in the first 5 years. The single-dose strategy, which is simpler and less expensive than the standard two-dose scheme, can be a good alternative for future vaccination policies in other countries where HA is endemic.