INTRODUCTION The Cuban national program for childhood immunizations began in 1962 and has included a surveillance system for monitoring adverse events following immunization since 1999. The expected rate of adverse events following childhood immunization in Cuba is 50 per 100,000 vaccine doses administered. In 2017, Pinar del Río Province reported higher-than-expected rates of adverse events, which motivated this study on their frequency and types.

OBJECTIVE Characterize adverse events following immunization reported in children in Pinar del Río Province in 2017.

METHODS We examined reports of adverse events following immunization in children from 2 months through 14 years of age in Pinar del Río Province, Cuba, from January 1, 2017 through December 31, 2017. We found 487 adverse events that met the criteria established by the national surveillance system. Information was obtained from epidemiological surveys of adverse events following immunization in Pinar del Río Province municipalities. Recorded were age, municipality, signs and symptoms, vaccine type, number of doses, anatomical site and route of vaccine administration, and the institution where the child was vaccinated. We estimated proportions for intensity and frequency related to vaccination, and calculated rates for 100,000 vaccine doses administered. We then compared the rates of observed adverse events with those of expected events.

RESULTS The overall rate of adverse events was 305.6 per 100,000 doses administered. Highest rates were reported in children aged <1 year (580.9 per 100,000 doses administered); in Guane Municipality (610 per 100,000 doses), for the pentavalent (DTwP-HB-Hib) vaccine (1567.7 per 100,000 doses), and in applications to the anterolateral quadrant of the thigh (772.5 per 100,000 doses). Symptoms classified as moderate, common, and general occurred more often, with fever being the most frequent. Severe induration, hypotonic and hyporesponsive episodes, persistent crying and rashes were observed more frequently than expected.

CONCLUSIONS The rate of adverse events following childhood immunization is similar to that reported in other provinces and elsewhere in the world. Of all childhood vaccines, the pentavalent vaccine is the most reactogenic. The absence of serious adverse events demonstrates the safety of childhood immunization in Cuba.

KEYWORDS Immunization programs, vaccination, surveillance system, adverse events, Cuba

INTRODUCTION Cuba has implemented an effective National Immunization Program since 1962. The schedule, administered primarily to children, comprises 11 vaccines (8 domestically produced) protecting against 13 diseases. In 1999 Cuba launched a national vaccine adverse event surveillance system to monitor and assess the safety of the immunization program, its vaccination procedures and the products administered.

OBJECTIVES Describe adverse events following vaccination reported in children aged <16 years in Cuba from 1999 through 2008.

METHODS A retrospective descriptive study was conducted of adverse events following vaccination reported from January 1999 through December 2008. Variables used: year, number of adverse events, province, type of vaccine, type and severity of adverse events (common minor, rare, severe), vaccination program errors, number of deaths, and final results of investigations of severe events. Percentages and rates per dose administered were calculated. Adverse event rates were calculated per 100,000 doses administered and by percentages of individual effects among events reported.

RESULTS A total of 45,237,532 vaccine doses were administered, and 26,159 vaccine-associated adverse events were reported (overall rate: 57.8 per 100,000 doses). The group aged 0–5 years reported the highest rate of vaccine-associated adverse events (82/100,000 doses). The DTwP vaccine exhibited the highest rate of adverse events. Common minor events were: fever (17,538), reactions at injection site (4470) and systemic side effects (2422). Rare events (by WHO definition) reported were: persistent crying (2666), hypotonic-hyporesponsive episodes (3), encephalopathy (2) and febrile seizures (112). Severe events included: anaphylaxis (2), respiratory distress (1), multiple organ failure (1), sudden death (1), vaccine-associated paralytic poliomyelitis (2), toxic shock syndrome (3), and sepsis (1). The 10 deaths and 3 cases of disability were investigated by an expert commission, which concluded that 8 of the 13 severe events were vaccination-related.

CONCLUSIONS Low rates of severe vaccine-associated adverse events observed in this study underline the low risk of vaccination relative to its demonstrated benefits in Cuba. Decision-making for the continued success of the National Immunization Program is supported by reliable information from comprehensive national surveillance with standarized reporting, along with multidisciplinary expert analysis of rare and severe adverse events and program errors.

KEYWORDS Immunization, immunization programs, vaccines, vaccination, product surveillance, postmarketing, adverse drug event, communicable disease control, Cuba