Effectiveness of palivizumab immunoprophylaxis to prevent respiratory syncytial virus hospitalizations in healthy full-term <6-month-old infants from the circumpolar region of Nunavik, Quebec, Canada

Abstract

In Quebec, Canada, eligibility for palivizumab (PVZ) immunoprophylaxis was expanded in fall 2016 to include healthy-full-term (HFT) infants residing in the circumpolar region of Nunavik and aged <3 months at the start of the RSV season or born during the season. This study assessed the effectiveness of PVZ to prevent RSV hospitalizations in these infants during the 3 seasons following its implementation. Medical and laboratory records of <1-year-old infants (375 average annual birth cohort) admitted to regional and tertiary hospitals with respiratory infection during 6 years were reviewed. Individual pharmacy data and birth registries were used to estimate adherence to PVZ and direct PVZ effectiveness in 0–5-month-old HFT infants by comparing the incidence of RSV hospitalizations 1) in protected and unprotected infants, and 2) during PVZ-protected and unprotected days. Over six seasons, the RSV hospitalization rate was 50.2/1000 (72.6/1000 adjusted for underdetection) in <1-year-old infants. PVZ was administered to 73% (469) of eligible HFT infants; 37% (237) received all recommended doses. Overall for the three RSV seasons the incidence of RSV hospitalization in PVZ-protected infants was similar to PVZ-unprotected infants, resulting in PVZ direct effectiveness of −6.7% (95% CI −174.8%, 85.6%). The incidence of RSV hospitalization during PVZ-protected and during PVZ-unprotected days was also similar, resulting in PVZ direct effectiveness of −3.8% (CI −167.6%, 64.9%). Over three RSV seasons, there was no evidence that PVZ reduced RSV hospitalizations in HFT Nunavik infants. In addition, the sub-optimal adherence to the recommended PVZ administration schedule suggests feasibility and acceptability issues.

Effectiveness and cost-effectiveness of RSV infant and maternal immunization programs: A case study of Nunavik, Canada

“…Patient visits first occur at local nursing stations and if specialized medical care is required, they will be airlifted to a regional hospital. Children who require more specialized care not available in Nunavik are evacuated to Montreal Children's Hospital by air ambulance [ 24 , 25 ].…”

“…Nunavik is the homeland of the Quebec Inuit situated in the northern third of this Canadian province. Current RSV immunization programs in Nunavik recommend the administration of the anti-RSV monoclonal antibody, palivizumab (Synagis®) to prematurely-born infants under 6 months of age and children with certain comorbidities under 2 years of age during the RSV season [24] , [25] , [26] . Palivizumab is a passive immunizing agent that is dosed monthly for up to 5 doses each season [26] , [27] , [28] .…”

“…Palivizumab is a passive immunizing agent that is dosed monthly for up to 5 doses each season [26] , [27] , [28] . Due to high RSV burden among new-born infants in this region, beginning the fall of 2017, Nunavik's immunization program expanded seasonal palivizumab's eligibility criteria to healthy full-term infants aged 0–2 months as a specific pilot project [ 24 , 25 , 29 ]. Palivizumab was offered to all high-risk and eligible healthy full-term infants during the RSV season.…”

“…Palivizumab was offered to all high-risk and eligible healthy full-term infants during the RSV season. However, recent reviews by Nunavik Public Health and the Institut national de santé publique du Québec (INSPQ) raised concerns of the feasibility, ethical issues, and real-world effectiveness of palivizumab pilot program specific to healthy full-term infants in Nunavik [ 24 , 30 ], and the program was not continued. Given the high costs of palivizumab programs associated with monthly injections [ 23 , [31] , [32] , [33] ] and a high unmet medical need for RSV prevention, there is a need to evaluate the effectiveness and cost-effectiveness of alternative RSV prophylactic strategies for the infant population in Nunavik [ 27 , 34 , 35 ].…”

Respiratory syncytial virus and palivizumab prophylaxis in the COVID-19 era

“…In 2017, Mitchell and Peiris 4 correctly pointed out that the social determinants of health need to be addressed when con sidering the effectiveness of PVZ prophy laxis for infants in the Artic with RSV. 5 If they have not already done so, all Canad ian PVZ programs need to immediately stop prophylaxis. Prophylaxis guidelines should be reviewed, with a switch to a flexible response to RSV activity.…”