PREDICTORS OF WILLINGNESS TO CO-PAY FOR COVID-19 PRE/POST-EXPOSURE PROPHYLAXIS AMONG US ADULTS: A TWO-PART HURDLE ANALYSIS
Author(s)
Michelle E. Orme, PhD1, Rodolphe Perard, MSc, PharmD2, Mark Orme, -1.
1ICERA Consulting Ltd, Swindon, United Kingdom, 2SHIONOGI B.V., London, United Kingdom.
1ICERA Consulting Ltd, Swindon, United Kingdom, 2SHIONOGI B.V., London, United Kingdom.
OBJECTIVES: Assess the willingness to co-pay for COVID-19 pre/post-exposure prophylaxis (PrEP/PEP) among US respondents and quantify differences.
METHODS: In an online, structured survey (May-June 2025), respondents were asked to select "the maximum acceptable co-payment for a medicine to prevent COVID-19 infections". Two dependent variables were included: willingness to co-pay (yes/no); acceptable co-pay ($0-$100). Pre-specified covariates included clinical need for PrEP/PEP (immunocompromised, other risk factors, or healthy control [reference]), age (age + age²), and binary variables male, white, vaccinated, long COVID, severe COVID-19, and hospitalised for COVID-19. The primary model was a two-part hurdle with robust standard errors. Pre-specified sensitivity analyses included alternative models (OLS, Tobit), age specifications, missing data handling, and removal of influential observations (Cook's distance > 4/N). Diagnostic tests were performed to assess multicollinearity and aid model comparison.
RESULTS: The regression included 8,439 responses with a mean co-pay of $24.20 (SD 21.6); 88.9% selected a co-pay > 0 and mean co-pay was $27.20 (SD 21.0) if co-pay > 0. Using the two-part hurdle model, the key predictor of whether a respondent was willing to accept any co-pay was vaccination status (OR 2.07, 95% CI 1.73, 2.47 vs unvaccinated). The key factors predicting how much was acceptable were previous COVID-19 hospitalisation (+$8.16; 95% CI +4.31, +12.02), male (+$4.23; 95% CI +3.21, +5.25), and age (linear −$0.09, 95% CI −0.14, −0.05; quadratic +$0.005, 95% CI +0.003, +0.007). Sensitivity analyses indicated that the primary model results were robust.
CONCLUSIONS: Vaccinated respondents were twice as likely to accept any co-pay as unvaccinated respondents. Among those willing to co-pay, the highest acceptable amounts came from respondents previously hospitalised for COVID-19, men, and younger respondents; clinical need for PrEP/PEP was not an independent predictor. Findings were robust across pre-specified sensitivity analyses.
METHODS: In an online, structured survey (May-June 2025), respondents were asked to select "the maximum acceptable co-payment for a medicine to prevent COVID-19 infections". Two dependent variables were included: willingness to co-pay (yes/no); acceptable co-pay ($0-$100). Pre-specified covariates included clinical need for PrEP/PEP (immunocompromised, other risk factors, or healthy control [reference]), age (age + age²), and binary variables male, white, vaccinated, long COVID, severe COVID-19, and hospitalised for COVID-19. The primary model was a two-part hurdle with robust standard errors. Pre-specified sensitivity analyses included alternative models (OLS, Tobit), age specifications, missing data handling, and removal of influential observations (Cook's distance > 4/N). Diagnostic tests were performed to assess multicollinearity and aid model comparison.
RESULTS: The regression included 8,439 responses with a mean co-pay of $24.20 (SD 21.6); 88.9% selected a co-pay > 0 and mean co-pay was $27.20 (SD 21.0) if co-pay > 0. Using the two-part hurdle model, the key predictor of whether a respondent was willing to accept any co-pay was vaccination status (OR 2.07, 95% CI 1.73, 2.47 vs unvaccinated). The key factors predicting how much was acceptable were previous COVID-19 hospitalisation (+$8.16; 95% CI +4.31, +12.02), male (+$4.23; 95% CI +3.21, +5.25), and age (linear −$0.09, 95% CI −0.14, −0.05; quadratic +$0.005, 95% CI +0.003, +0.007). Sensitivity analyses indicated that the primary model results were robust.
CONCLUSIONS: Vaccinated respondents were twice as likely to accept any co-pay as unvaccinated respondents. Among those willing to co-pay, the highest acceptable amounts came from respondents previously hospitalised for COVID-19, men, and younger respondents; clinical need for PrEP/PEP was not an independent predictor. Findings were robust across pre-specified sensitivity analyses.
Conference/Value in Health Info
2026-11, ISPOR Europe 2026, Vienna, Austria
Value in Health, Volume 29, Issue 12S
Code
PCR65
Topic
Patient-Centered Research
Topic Subcategory
Patient Behavior and Incentives
Disease
Infectious Disease (non-vaccine), No Additional Disease & Conditions/Specialized Treatment Areas