Modeling undetected poliovirus circulation following the 2022 outbreak in the United States

ABSTRACT

Background

New York State (NYS) reported a polio case (June 2022) and outbreak of imported type 2 circulating vaccine-derived poliovirus (cVDPV2) (last positive wastewater detection in February 2023), for which uncertainty remains about potential ongoing undetected transmission.

Research Design and Methods

Extending a prior deterministic model, we apply an established stochastic modeling approach to characterize the confidence about no circulation (CNC) of cVDPV2 as a function of time since the last detected signal of transmission (i.e. poliovirus positive acute flaccid myelitis case or wastewater sample).

Results

With the surveillance coverage for the NYS population majority and its focus on outbreak counties, modeling suggests a high CNC (95%) within 3–10 months of the last positive surveillance signal, depending on surveillance sensitivity and population mixing patterns. Uncertainty about surveillance sensitivity implies longer durations required to achieve higher CNC.

Conclusions

In populations that maintain high overall immunization coverage with inactivated poliovirus vaccine (IPV), rare polio cases may occur in un(der)-vaccinated individuals. Modeling demonstrates the unlikeliness of type 2 outbreaks reestablishing endemic transmission or resulting in large absolute numbers of paralytic cases. Achieving and maintaining high immunization coverage with IPV remains the most effective measure to prevent outbreaks and shorten the duration of imported poliovirus transmission.

KEYWORDS:

• Polio
• eradication
• dynamic modeling
• outbreak response
• IPV

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Author contributions

The Kid Risk authors (DAK, KB, and KMT) contributed to all parts of this manuscript; DAK led the analysis and prepared the first draft of the manuscript; all other authors contributed to the ascertainment and interpretation of the NYS data and revisions to the manuscript. All authors approve of and agree to be accountable for the manuscript.

Acknowledgments

The authors thank Steve Oberste, Sarah Kidd, David Larsen, Daniel Lang, Kirsten St. George, Meghan Fuschino, Emily Lutterloh, Mark Sotir, David Sugerman, and members of the CDC Polio and Picornavirus Laboratory Branch for helpful discussions.

Disclaimer

The views expressed are solely those of the authors and do not necessarily represent the official views of the US Centers for Disease Control and Prevention, Department of Health and Human Services, the New York State Department of Health, or the New York City Department of Health and Mental Hygiene.

Additional information

Funding

The authors from Kid Risk, Inc. (DAK, KB, and KMT) acknowledge support for this publication under the Cooperative Agreement Number [NU2RGH001915-03-00] funded by the Centers for Disease Control and Prevention.