Public health impact of delaying second dose of BNT162b2 or mRNA-1273 covid-19 vaccine: simulation agent based modelling study

May 12, 2021

Santiago Romero-Brufau, assistant professor of medicine and healthcare systems engineering, instructor12, Ayush Chopra, masters student3, Alex J Ryu, assistant professor of medicine1, Esma Gel, associate professor4, Ramesh Raskar, associate professor3, Walter Kremers, associate professor biostatistics5, Karen S Anderson, professor4, Jayakumar Subramanian, senior research scientist6, Balaji Krishnamurthy, principal scientist and director6, Abhishek Singh, masters student3, Kalyan Pasupathy, associate professor of health care systems engineering5, Yue Dong, assistant professor7, John C O’Horo, associate professor of medicine1, Walter R Wilson, professor of medicine1, Oscar Mitchell, fellow, pulmonary and critical care medicine8, Thomas C Kingsley, assistant professor of medicine1


Romero-Brufau et al. evaluated the population effects of delaying the second dose of COVID-19 vaccines compared to the standard dosing schedule (21 or 28 days), with the goal to determine whether delaying second doses to give more individuals the first dose results in more widespread immunity. The authors simulated a population of 100,000 and included family, occupational, and random networks that could result in encounters with COVID-19 positive individuals. When the vaccination rate was held constant at 0.3% and the vaccine efficacy estimates were varied, the authors determined that delaying the second dose was favorable only for vaccines with greater than 70% efficacy. Varying the vaccination rate while holding first dose efficacy at 80% revealed that delaying the second dose is favorable for vaccination rates below 0.3%. The authors also examined age-split dosing strategies and found that delaying the second dose for all individuals under 65 years was favorable, assuming 80% first dose vaccine efficacy and a vaccination rate of 1% or less. The authors suggest that, under certain conditions, delaying the second dose is favorable and that certain age-split dosing strategies can reduce absolute mortality between 26 and 47 per 100,000.

Romero-Brufau S, Chopra A, Ryu AJ, et al. Public health impact of delaying second dose of BNT162b2 or mRNA-1273 covid-19 vaccine: simulation agent based modeling study. BMJ 2021; 373: n1087.

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