Summary of the NACI Update on Immunization in Pregnancy with Tetanus Toxoid, Reduced Diphtheria Toxoid and Reduced Acellular Pertussis (Tdap) Vaccine.

BACKGROUND: In Canada, pertussis is an endemic and cyclical disease, with peaks occurring at two- to five-year intervals. Although pertussis incidence varies by age group, unvaccinated or undervaccinated infants are at greatest risk of infection and associated complications. Since the last National Advisory Committee on Immunization (NACI) recommendations published in 2014, new evidence on the safety and effectiveness of tetanus toxoid, reduced diphtheria toxoid and reduced acellular pertussis (Tdap) vaccine administration in pregnancy has become available. OBJECTIVE: To provide guidance on maternal immunization in pregnancy as a strategy to reduce disease incidence and severe outcomes (defined as hospitalization or death) from pertussis infection in infants less than 12 months of age. METHODS: The NACI reviewed evidence on the burden of disease in Canada, vaccine safety and immunogenicity and vaccine effectiveness in jurisdictions that have implemented maternal immunization programs. A total of 59 articles were identified, retrieved and included in the literature review to inform this statement. RESULTS: In the majority of reviewed studies, post immunization increases in antibody levels resulted in more than 90% of women achieving anti-PT levels greater than or equal to 10 IU/ml one month following immunization. In infants, maternal immunization was found to result in increased pertussis antibody concentrations. In the majority of studies, following the receipt of the fourth diphtheria, tetanus and pertussis (DTaP) dose after 15 months of age, no statistically significant differences in antibody levels and avidity were observed between infants whose mothers received Tdap in pregnancy and those whose mothers did not receive Tdap in pregnancy. No major maternal or infant safety issues, including pregnancy outcomes, were reported in the reviewed literature. Effectiveness of maternal Tdap immunization in pregnancy was estimated to be over 90% against pertussis in infants younger than two months of age, with no deaths observed among infants whose mothers received Tdap prior to 36 weeks of pregnancy. Maternal immunization with Tdap in pregnancy also resulted in a reduction in infant disease severity and hospitalization. Vaccine effectiveness was also reported to persist after the receipt of the first three DTaP doses, with immunization in pregnancy resulting in additional protection of up to 70% in children whose mothers received Tdap in pregnancy. CONCLUSION: There is now strong evidence to support the NACI recommendation that immunization with Tdap vaccine should be offered in every pregnancy. This is ideally administered between 27 and 32 weeks of gestation but evidence also supports providing maternal Tdap over a wider range of gestational ages, from 13 weeks up to the time of delivery, in view of programmatic and unique patient considerations.

Updated NACI recommendations for measles post-exposure prophylaxis.

BACKGROUND: Human immune globulin (Ig) products are currently recommended as post-exposure prophylaxis (PEP) for measles in certain susceptible groups. However, successful measles vaccination programs in North America have led to low circulation of measles virus and most blood donors now have vaccine-derived immunity. Concurrently, the concentrations of anti-measles antibodies in human Ig products have shown trends of gradual decline and previously recommended doses and routes of administration may no longer be optimally protective. OBJECTIVES: To review the literature and update recommendations on post-exposure prophylaxis for measles, including dosing and route of administration, for measles Ig PEP in susceptible infants and in individuals who are immunocompromised or pregnant, in order to prevent severe disease. APPROACH: The National Advisory Committee on Immunization (NACI) Measles, Mumps, Rubella, Varicella Working Group reviewed key literature, international practices, and product information for current Ig products pertaining to the optimal dosage and routes of Ig administration for measles PEP. It then proposed evidence-based changes to the PEP recommendations that were considered and approved by NACI. RESULTS: NACI continues to recommend that susceptible immunocompetent individuals six months of age and older, who are exposed to measles and who have no contraindications be given measles-mumps-rubella (MMR) vaccine within 72 hours of the exposure. NACI recommends that for susceptible infants younger than six months of age, if injection volume is not a major concern, intramuscular immunoglobulin (IMIg) should be provided at a concentration of 0.5 mL/kg, to a maximum dose of 15 mL administered over multiple injection sites. Susceptible infants six to 12 months old who are identified after 72 hours and within six days of measles exposure should receive IMIg (0.5 mL/kg) if injection volume is not a major concern. For susceptible contacts who are pregnant or immunocompromised, if injection volume is not a concern, IMIg can be provided at a concentration of 0.5 mL/kg understanding that recipients 30 kg or more will not receive the measles antibody concentrations that are considered to be fully protective. Alternatively, in cases where injection volume is a major concern or for recipients 30 kg or more, intravenous immunoglobulin (IVIg) can be provided at a dose of 400 mg/kg.NACI does not recommend that susceptible immunocompetent individuals older than 12 months of age receive Ig PEP for measles exposure due to the low risk of disease complications and the practical challenges of administration for case and contact management. CONCLUSION: NACI has updated the recommendations for measles PEP to reflect current evidence and best practices in order to prevent severe disease in Canada. Consistent with recommendations in other countries, this includes consideration of off-label use of IVIg in some instances.

New vaccine administration practice recommendations from the Canadian Immunization Guide.

BACKGROUND: The Canadian Immunization Guide (CIG) is published online by the Public Health Agency of Canada and summarizes guidance on vaccines for human use into a single resource. Chapters are reviewed and updated on a regular basis. Vaccine administration is a critical part of any immunization program. Recently, the CIG chapter on vaccine administration practices was updated. OBJECTIVE: To provide highlights of recent changes to the Vaccine Administration Practices chapter of the CIG. APPROACH: Vaccine-specific guidance in the CIG is based on National Committee on Immunization (NACI) and Committee to Advise on Tropical Medicine and Travel (CATMAT) recommendations as well as new recommendations developed by the CIG Working Group members and NACI Secretariat technical staff. New recommendations are based on a review of the literature, including systematic reviews when available, a review of guidance provided by other National Immunization Technical Advisory Groups and expert opinion. The revisions are approved by the Working Group chair, as well as NACI. RESULTS: Highlights of new recommendations include the following: vaccine providers should adhere to jurisdictional or organizational policies and procedures regarding combining the contents of multi-dose vials; clinical judgement should be used when selecting needle length for intramuscular injections that takes into account the vaccine recipient's weight, gender and age; filter needles are not recommended for vaccine administration as they may filter out active ingredients such as adjuvants; an injection site other than in an area where lymphatic drainage may be impaired should be considered; there is no evidence or theoretical rationale for avoiding injection through a tattoo or superficial birthmark; and immunization pain management strategies have now been developed for all ages. CONCLUSION: Recommendations in vaccine administration practices have recently been changed in some important ways. The Public Health Agency of Canada is committed to providing information on immunization in an easily accessible, reader-friendly format for healthcare providers and policy-makers.

Summary of the NACI Update on the Recommended Use of Hepatitis B Vaccine.

BACKGROUND: Infant and adolescent hepatitis B (HB) immunization programs have been successfully implemented in all Canadian provinces and territories since the 1990s. Following the introduction of universal immunization programs, the incidence of HB has decreased in all age groups. However, the duration of protection against chronic infection, as measured by preserved T- and B-cell memory, remains unknown. OBJECTIVES: To review the evidence on long-term protection against HB in adolescents who received routine immunization in infancy, determine the level of risk of HB infection in Canadians with diabetes and assess the timing of re-vaccination of individuals with immunocompromising conditions. METHODS: The National Advisory Committee on Immunization (NACI) Hepatitis Working Group reviewed key questions and performed an evidence review and synthesis. In consideration of the burden of illness to be prevented, the target population and issues related to safety, immunogenicity, efficacy and effectiveness of the vaccine, the group proposed recommendations for vaccine use to NACI. All evidence was rated and summarized in tables. NACI approved specific evidence-based recommendations and elucidated the rationale and relevant considerations in the Statement update. RESULTS: In addition to the epidemiological data assessment, NACI reviewed evidence from efficacy and effectiveness studies with up to 30 years of follow-up data as well as data from 39 publications on immune response following the administration of a HB booster dose in individuals who were immunized as infants. Based on the conducted review, NACI did not find evidence that would support a change to its current recommendation that there is no need for routine booster immunization of individuals immunized in infancy and that there is no evidence to support preferential immunization schedules or routine immunization of individuals with diabetes. CONCLUSION: NACI now recommends that following immunization of immunocompromised individuals, initial annual monitoring of HB antibody levels may be considered.

Immunization guidance products: Different levels of detail for different uses.

The National Advisory Committee on Immunization (NACI) provides expert and evidence-based advice to the Public Health Agency of Canada (PHAC) on the use of human vaccines in Canada. This advice is presented in a variety of publications for different uses. A recent survey identified some confusion regarding the various NACI publication products. The objective of this article is to identify the level of detail and appropriate uses of the different NACI products. NACI statements provide a synthesis of current evidence and expert opinion on new vaccines or new indications for vaccines to inform immunization practices, policies and programs. NACI literature reviews inform new NACI statements and are published after the statement to inform readers about current literature on a specific immunization topic. The Canadian Immunization Guide (CIG) is a practice-oriented guide that synthesizes all the NACI statements and is updated regularly. NACI statement summaries are published in the Canada Communicable Disease Report (CCDR) and provide a high level overview of these statements shortly after they are published. These products provide a variety of options for users to choose how in-depth they wish to explore the evidence base and process for producing recommendations for immunization in Canada.

Summary of NACI Statement: Interim Recommendations on the Use of Pneumococcal Vaccines in Immunocompetent Adults 65 Years of Age and Older.

BACKGROUND: Since 2015, pneumococcal 13-valent conjugate vaccine (PNEU-C-13) has been authorized for the prevention of invasive pneumococcal disease (IPD) and pneumococcal community-acquired pneumonia (CAP) in adults. Adults with immunocompromising conditions are still recommended to receive PNEU-C-13 followed by the pneumococcal 23-valent polysaccharide vaccine (PNEU-P-23). NACI guidance has been requested on the use of PNEU-C-13 vaccine in immunocompetent adults 65 years of age and older. OBJECTIVES: To make recommendations, at the individual level, for the use of PNEU-C-13 in immunocompetent adults 65 years of age and over. METHODS: The NACI Pneumococcal Working Group (PWG) reviewed key questions and performed an evidence review and synthesis. In consideration of the burden of illness to be prevented, the target population, safety, immunogenicity, efficacy and effectiveness of the vaccine, the PWG proposed recommendations for vaccine use to NACI. All evidence was rated and reported in evidence tables. NACI approved specific evidence-based recommendations and elucidated the rationale and relevant considerations in the statement update. RESULTS: NACI identified and reviewed evidence from one randomized controlled trial investigating the efficacy of PNEU-C-13 to prevent IPD and CAP in adults who were immunocompetent at enrollment and three clinical trials assessing the immunogenicity in immunocompetent and immunocompromised adults. CONCLUSIONS: Based on reviewed evidence, NACI issued new recommendations for the use of pneumococcal vaccines in immunocompetent adults 65 years of age and older.

Summary of the National Advisory Committee on Immunization (NACI) Statement Update on the Recommended Use of Hepatitis A Vaccine.

BACKGROUND: The severity of hepatitis A (HA) increases with age. Children less than six years of age are commonly asymptomatic or present with mild disease without jaundice and represent an important source of infection, particularly for household members and other close contacts. In older children and adults, HA is typically symptomatic. Older persons and individuals with chronic liver disease and immunocompromising conditions have an increased risk of progressing to fulminant hepatic failure resulting in death. Immunization with HA vaccine is recommended for pre-exposure immunization of persons at increased risk of infection or severe HA, as well as within 14 days of HA exposure for: susceptible household and close contacts of proven or suspected cases of HA; co-workers and clients of infected food handlers; and staff and attendees of group child care centres and kindergartens where HA has occurred. Canada's National Advisory Committee on Immunization (NACI) has previously recommended HA vaccination for persons one year of age and over. OBJECTIVES: To make recommendations for the use of HA vaccine in infants less than one year of age and to clarify recommendations for the post-exposure use of human immune globulin (Ig). METHODS: The NACI Hepatitis Working Group (HWG) performed literature reviews and reviewed vaccine manufacturer provided data on the topic of HA post-exposure prophylaxis. All evidence was rated and reported in evidence tables. A knowledge synthesis was performed and NACI approved specific evidence-based recommendations, elucidating the rationale and relevant considerations. RESULTS: No studies on the efficacy or effectiveness of HA-containing vaccines in children six to less than 12 months of age were identified through the literature search. Receipt of two doses of HA-containing vaccines was found to be safe and immunogenic in infants six to 12 months of age. Limited data were available regarding HA-containing vaccine immunogenicity in adults over the age of 40 years. CONCLUSION: There are now new NACI recommendations on HA vaccine and post-exposure use of Ig.