Effectiveness of an outbreak dose of mumps-containing vaccine in two First Nations communities in Northern Ontario, Canada

ABSTRACT

Between 18 Dec 2017 and 27 June 2018, a mumps outbreak occurred in two Canadian Indigenous communities. An outbreak dose of mumps-containing vaccine was offered as part of control measures. We conducted a cohort study and survival analysis to describe the outbreak and evaluate the outbreak dose, extracting vaccination information on all community members (n = 3,135) from vaccination records. There were 70 mumps cases; 56% had received two pre-outbreak vaccine doses. Those who received a pre-outbreak dose more distantly had higher rates of mumps compared to those with more recent doses (adjusted hazard ratio = 3.4 (95%CI: 0.7–20.6) for receipt >20 years before vs. receipt ≤3 years). During the outbreak, 33% (1,010/3,080) of eligible individuals received an outbreak dose. The adjusted hazard ratio for no outbreak dose receipt was 2.7 (95%CI: 1.0–10.1). Our results suggest that an outbreak dose of mumps-containing vaccine may be an effective public health intervention, but further study is warranted.

KEYWORDS:

• Mumps
• measles-Mumps-Rubella Vaccine
• immunization
• outbreak dose
• vaccine Effectiveness

Acknowledgments

We are very grateful to Deer Lake First Nation and Sandy Lake First Nation for sharing their experiences and for the support from community leadership, including the Chiefs, Band Council Members and the Health Directors. We deeply appreciate the contributions of the dedicated nurses, the Keewaytinook Okimakanak Tribal Council, the Sioux Lookout First Nations Health Authority, the Northwestern Health Unit and the Ontario Ministry of Health and Long-Term Care to the outbreak response. We would especially like to thank Susan Conway, Leanne Coward, and Melanie Varin (all from Indigenous Services Canada) and Kathleen Laberge (Public Health Agency of Canada Canadian Field Epidemiology Program) who contributed to the success of this project.

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website at https://doi.org/10.1080/21645515.2020.1870909

Additional information

Funding

This work was conducted as part of the outbreak response and did not receive any external funding.