Vaccine safety implications of Ontario, Canada's switch from DTaP-IPV to Tdap-IPV for the pre-school booster

Implementation challenges and real-world impacts of switching pediatric vaccines: A global systematic literature review

Switching a vaccine for another on a pediatric national immunization program is often done for the betterment of society. However, if poorly implemented, switching vaccines could result in suboptimal transitions with negative effects. A systematic review was conducted to evaluate the existing knowledge from identifiable documents on implementation challenges of pediatric vaccine switches and the real-world impact of those challenges. Thirty-three studies met the inclusion criteria. We synthesized three themes: vaccine availability, vaccination program deployment, and vaccine acceptability. Switching pediatric vaccines can pose unforeseen challenges to health-care systems worldwide and additional resources are often required to overcome those challenges. Yet, the magnitude of the impact, especially economic and societal, was frequently under-researched with variability in reporting. Therefore, an efficient vaccine switch requires a thorough consideration of the added benefits of replacing the existing vaccine, preparation, planning, additional resource allocation, implementation timing, public-private partnerships, outreach campaigns, and surveillance for program evaluation.

Review of scientific evidence to support recommendations of the full-dose DTaP-IPV vaccination in pre-school age children in Italy

INTRODUCTION

Two vaccine formulations are available to prevent diphtheria, tetanus, pertussis, and poliomyelitis: the pediatric full-dose (DTaP-IPV) and the reduced dose formulation (dTap-IPV). Different immunization schedules are internationally recommended for the pre-school booster dose.

AREAS COVERED

International and Italian recommendations, scientific evidence on immunogenicity and safety of DTaP/dTap vaccines to support the full dose as a pre-school booster and Italian vaccination coverage (VC) up to adolescence.

EXPERT OPINION

The WHO recommends a '3+1' schedule with DTaP vaccine for primary immunization, followed by a pre-school booster with DTaP or dTap vaccine. In Italy, a '2+1' schedule, with no booster in the second year, and a pre-school booster dose are recommended with DTPa-IPV vaccines. Studies showed a non-inferior immunogenicity in dTap vaccinees in pre-school age; nevertheless, the antibody titers were usually greater in children vaccinated with DTaP, while lower frequencies of adverse events were recorded in children receiving dTap. Italian VCs for pre-school and adolescent boosters have not been satisfactory, which further reduced during the COVID-19 period. In Italy, the pre-school booster offers the last chance to receive a full dose of DTaP vaccine, thus, representing the most suitable intervention to provide lasting protection in children.

Surveillance of adverse events following the introduction of inactivated poliovirus vaccine made from Sabin strains (sIPV) to the Chinese EPI and a comparison with adverse events following inactivated poliovirus vaccine made from wild strains (wIPV) in Jiangsu, China

One dose of inactivated poliovirus vaccine (IPV) was introduced into the Chinese Expanded Program on Immunization (EPI) in 2016. IPV made from Sabin strains (sIPV) was newly licensed in China and its safety has been concerned. This study aimed to evaluate the safety of sIPV and provide a comparison with conventional IPV made from wild strains (wIPV). We collected all IPV-related AEFI reports in Jiangsu from the Chinese National Adverse Events Following Immunization Information System (CNAEFIS) for 2016-2019. We obtained the administered doses of IPV from the Jiangsu provincial Electronic Immunization Registries System (JSEIRS). The AEFI reporting rates per 100,000 doses of vaccine administered were compared for sIPV and wIPV. A total of 699 sIPV and 908 wIPV AEFI cases were collected by CNAEFIS in Jiangsu during 2016-2019. The overall AEFI reporting rates were 53.02 per 100,000 doses and 41.25 per 100,000 doses for sIPV and wIPV, respectively (P < .001). For both sIPV and wIPV, the AEFIs were mainly classified as common adverse reactions. The reporting rate of common adverse reactions was higher for sIPV than for wIPV (P < .001). The most frequently reported symptoms/signs were fever, persistent crying, injection site erythema/swelling, rash, and injection site induration. Only 1.14% of sIPV-associated and 2.31% of wIPV-associated AEFI cases were diagnosed as serious. No difference in reporting rate was observed for serious AEFIs (P = .272). sIPV has a favorable safety profile, although it exhibits a slightly higher reporting rate of common adverse reactions than wIPV.

Use of tetanus-diphtheria (Td) vaccine in children 4-7 years of age: World Health Organization consultation of experts

For lifetime protection against diphtheria and tetanus, the World Health Organization (WHO) recommends six doses of diphtheria and tetanus containing vaccines. Td (reduced diphtheria toxoid, ≥2-5 IU) vaccines are currently licensed for ages 7 years and older, but use of Td vaccine for ages 4 years and older would have advantages for immunization programs in many low- and middle-income countries. For this reason, WHO convened an expert consultation to review the currently available evidence for the use of Td vaccine from 4 to 7 years of age which concluded: (1) no relevant biological difference in immune response in the relevant age group compared with children over 7 years of age; (2) adequate seroprotection in several studies with Td vaccine in the 4-7 age group and many studies using combination vaccines; (3) durable and protective response of at least 9-11 years duration in several longitudinal and modelling studies, (4) less reactogenicity compared with use of full-dose diphtheria vaccine, potentially improving the vaccination experience; and (5) adequate control of diphtheria in several countries using Td-containing combination vaccines in 4-7 year old children. On this basis, the experts concluded that from a programmatic perspective, Td vaccine given in ages 4-7 years, as a second booster dose in a six-dose series, would provide adequate protection against diphtheria and tetanus and recommended steps to include this change in age extension listed in the package insert.

Sepsis, parenteral vaccination and skin disinfection

ASBSTRACT Disinfection should be required for all skin penetrative procedures including parenteral administration of vaccines. This review analyses medically attended infectious events following parenteral vaccination in terms of their microbiological aetiology and pathogenesis. Like 'clean' surgical site infections, the major pathogens responsible for these events were Staphylococcal species, implicating endogenous con-tamination as a significant source of infection. As 70% isopropyl alcohol swabbing has been shown to effectively disinfect the skin, it would be medico-legally difficult to defend a case of sepsis with the omission of skin disinfection unless the very low risk of this event was adequately explained to the patient and documented prior to vaccination. There was a significant cost-benefit for skin disinfection and cellulitis. Skin disinfection in the context of parenteral vaccination represents a new paradigm of medical practice; the use of a low cost intervention to prevent an event of very low prevalence but of significant cost.

Best vaccination practice and medically attended injection site events following deltoid intramuscular injection

Analysis of medically attended injection site events data provides a vehicle to appreciate the inadequacies of vaccination practice for deltoid intramuscular injection and to develop best practice procedures. These data can be divided into 3 groups; nerve palsies, musculoskeletal injuries and cutaneous reactions and reflect inappropriate site of injection, needle over or under penetration, local sepsis and vascular complications. The aim of this review is to formulate best vaccination practice procedures for deltoid intramuscular injection of vaccines through the collation and analysis of medically attended injection site events.