Updated Statement on the use of Rotavirus Vaccines: An Advisory Committee Statement (ACS) National Advisory Committee on Immunization (NACI)†

Rotavirus vaccination in the neonatal intensive care units: where are we? A rapid review of recent evidence

PURPOSE OF REVIEW

Rotavirus is a leading cause of viral acute gastroenteritis in infants. Neonates hospitalized in neonatal intensive care units (NICUs) are at risk of rotavirus infections with severe outcomes. The administration of rotavirus vaccines is only recommended, in the United States and Canada, upon discharge from the NICU despite rotavirus vaccines being proven well tolerated and effective in these populations, because of risks of live-attenuated vaccine administration in immunocompromised patients and theoretical risks of rotavirus vaccine strains shedding and transmission.We aimed to summarize recent evidence regarding rotavirus vaccine administration in the NICU setting and safety of rotavirus vaccines in preterm infants.

METHODS

We conducted a rapid review of the literature from the past 10 years, searching Medline and Embase, including all study types except reviews, reporting on rotavirus vaccines 1 and 5; NICU setting; shedding or transmission; safety in preterm. One reviewer performed data extraction and quality assessment.

RECENT FINDINGS

Thirty-one articles were analyzed. Vaccine-derived virus shedding following rotavirus vaccines existed for nearly all infants, mostly during the first week after dose 1, but with rare transmission only described in the household setting. No case of transmission in the NICU was reported. Adverse events were mild to moderate, occurring in 10-60% of vaccinated infants. Extreme premature infants or those with underlying gastrointestinal failure requiring surgery presented with more severe adverse events.

SUMMARY

Recommendations regarding rotavirus vaccine administration in the NICU should be reassessed in light of the relative safety and absence of transmission of rotavirus vaccine strains in the NICU.

Evaluation of the Impact of a Rotavirus Vaccine Program on Pediatric Acute Gastroenteritis Hospitalizations: Estimating the Overall Effect Attributable to the Program as a Whole and as a Per-Unit Change in Rotavirus Vaccine Coverage

Estimation of the overall effect of a vaccine program is essential, but the effect is typically estimated for a whole program. We estimated the overall effect of the Quebec rotavirus vaccine program, launched in November 2011, and the effect for each 10% increase in rotavirus vaccine coverage on pediatric hospitalizations for all-cause acute gastroenteritis. We implemented negative binomial regressions adjusted for seasonality, long-term trends, and infection dynamics, to estimate the effect of the vaccine program as: 1) a dichotomous variable, representing program presence/absence, and linear term to account for changes in trend in the period after the program began; and 2) a continuous variable, representing rotavirus vaccine coverage. Using exposure 1, the vaccine program was associated with a 51.2% (95% confidence interval (CI): 28.5, 66.7) relative decline in adjusted weekly hospitalization rates for all-cause acute gastroenteritis as of December 28, 2014. Using exposure 2, a 10% increase in rotavirus ≥1-dose coverage was associated with a 7.1% (95% CI: 3.5, 10.5) relative decline in adjusted weekly rates, with maximum coverage of 87.0% associated with a 47.2% (95% CI: 26.9, 61.9) relative decline. Estimation of the overall effect attributable to a change in vaccine coverage might be a useful addition to standard measurement of the overall effect.

Trends in severe gastroenteritis among young children according to socio-economic characteristics before and after implementation of a rotavirus vaccination program in Quebec

OBJECTIVES

Following implementation of a publicly funded rotavirus immunization program in Quebec (Canada) in 2011, its impact on gastroenteritis hospitalization rates, a proxy for severe gastroenteritis, was assessed.

METHODS

Using a tertiary hospital database and a regional vaccination registry, temporal trends in rates of hospitalization for acute gastroenteritis (AGE) and rotavirus gastroenteritis before the age of five years and rotavirus vaccine coverage were examined from June 2004 through May 2014 in a large retrospective birth cohort in the Eastern Townships region. The mean annual AGE hospitalization rate in post-program years (2011/2012-2013/2014) was compared with that in pre-program years (2004/2005-2010/2011) overall and according to the characteristics of the children, families and residential neighbourhoods at birth.

RESULTS

The AGE hospitalization rate significantly decreased from 81/10,000 in the pre-program period to 46/10,000 in the post-program period (relative reduction = 43%). Following implementation of the program, vaccine coverage rapidly increased and reached 81%. All socio-economic categories showed a reduced hospitalization rate in the post-program period, but the lowest relative reductions were observed in children living in neighbourhoods with higher rates of unemployment, low-income families and single mothers. However, these disadvantaged subgroups did not have lower vaccine coverage.

CONCLUSIONS

Three years following its introduction in a universal vaccination program, rotavirus vaccine significantly reduced severe gastroenteritis in young children. Despite similar vaccine coverage among all children, disadvantaged socio-economic groups appeared to have a less pronounced AGE reduction, suggesting that factors other than vaccination could partially influence the reduction of gastroenteritis morbidity in young children.

Impact of a publicly funded monovalent rotavirus vaccination program in the Province of Quebec (Canada)

In November 2011, the province of Quebec, Canada implemented a publicly funded rotavirus (RV) vaccination program using the monovalent RV vaccine (RV1). To assess its impact, trends in passive RV laboratory detection and Emergency Department (ED) visits for gastroenteritis (GE) at two pediatric centers were evaluated.

METHODS

RV tests performed were extracted from the virology laboratory databases and ED visits for GE between July 1, 2006 and June 30, 2013, from the ED databases of The Montreal Children's Hospital (MCH) and Centre Hospitalier Universitaire de Sherbrooke (CHUS). The percent positive RV tests over time and season duration were assessed using 5-week moving averages. We defined season start and end as the first two and the last two consecutive weeks where the percent positive RV tests were ≥ 10%, respectively.

RESULTS

Comparing the pre- and post-vaccination program periods, a decrease in the proportion of positive RV tests was seen: 15.9% vs. 5.1% (p<0.001). Pre-vaccination program, RV seasons started between December and February, peaked in March or April and ended in May. In 2011-2012, the season started in March, peaked in April, and ended in May. In 2012-2013, the season lasted 3 weeks in May. ED visits for GE decreased post-introduction of the RV1 program: from 4.8% to 3.4% in 2011-2012, and 4.2% in 2012-13 (p<0.001). In children <2 years of age, ED GE visits decreased from 7.5% to 4.8% in 2011-2012, and 5.2% in 2012-2013 (p<0.001). Admissions for GE also decreased significantly from 0.41% of all ED visits to 0.14% in 2011-2012 and 0.22% in 2012-2013 (p<0.005).

CONCLUSION

Implementation of a publicly funded RV vaccination program had a major impact on the epidemiology of RV infections in Quebec: RV seasons have started later and been of shorter duration, peak positives were fewer, and ED visits for GE decreased.

Estimated hospitalizations attributed to norovirus and rotavirus infection in Canada, 2006-2010

Enteric viruses including norovirus and rotavirus are leading causes of gastroenteritis in Canada. However, only a small number of clinical cases are actually tested for these pathogens leading to systematic underestimation of attributed hospitalizations in administrative databases. The objective of this analysis was to estimate the number of hospitalizations due to norovirus and rotavirus in Canada. Hospitalization records for acute gastroenteritis-associated discharges at all acute-care hospitals in Canada between 2006 and 2011 were analysed. Cause-unspecified gastroenteritis hospitalizations were modelled using age-specific negative binomial models with cause-specified gastroenteritis admissions as predictors. The coefficients from the models were used to estimate the number of norovirus and rotavirus admissions. The total annual hospitalizations for rotavirus were estimated to be between 4500 and 10 000. Total annual hospitalizations for norovirus were estimated to be between 4000 and 11 000. The mean total annual cost associated with these hospitalizations was estimated to be at least $16 million for rotavirus and $21 million for norovirus (all figures in Canadian dollars). This study is the first comprehensive analysis of norovirus and rotavirus hospitalizations in Canada. These estimates provide a more complete assessment of the burden and economic costs of these pathogens to the Canadian healthcare system.

Clinicians' opinions on new vaccination programs implementation

In Canada, several new vaccines were recently approved for clinical use or are expected to be soon. Decision-makers are faced with the choice whether or not to include these vaccines in publicly funded vaccination programs. The aim of this study was to assess Canadian pediatricians' and family physicians' opinions regarding 7 new vaccines, and perceived priority for the introduction of new programs. A self-administered, anonymous, mail-based questionnaire was sent during fall 2009 to a random sample of 1182 family physicians and to all 1852 Canadian pediatricians. Responses to 8 statements regarding frequency and severity of the diseases, efficacy and safety of the vaccines as well as feasibility of immunization programs were used to calculate priority scores to rank the 7 potential new vaccination programs (calculated scores ranging from 0 to 100). Overall response rate was 43%. The majority of respondents perceived the health and economic burden of diseases prevented by the seven new vaccines as important and considered new vaccines to be safe and effective. More than 90% of physicians strongly agreed or agreed that the new vaccines would be or are currently well accepted by the public and by the health professionals who administer vaccines, except for the HPV and rotavirus vaccines (respectively 30% and 29% strongly agreed or agreed). Mean priority scores were: 77.4 out of 100 for the measles, mumps, rubella and varicella (MMRV) combined vaccine; 75.6 for the hexavalent (DTaP-IPV-Hib-HBV) vaccine; 73.1 for the new pneumococcal conjugate vaccines; 69.8 for the meningococcal ACYW135; 68.9 for the combined hepatitis A and B; 63.5 for the human papillomavirus vaccine and 56.9 for the rotavirus vaccine. Health professionals' opinion is an important element to consider in the decision-making process regarding implementation of new immunization programs. Without health professional support, the introduction of a new vaccination program may be unsuccessful. In this study, the MMRV and the hexavalent (DTaP-IPV-Hib-HBV) vaccines received the highest ratings.