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

Abstract

Objective To estimate population health outcomes with delayed second dose versus standard schedule of SARS-CoV-2 mRNA vaccination. Design Simulation agent based modeling study. Setting Simulated population based on real world US county. Participants The simulation included 100 000 agents, with a representative distribution of demographics and occupations. Networks of contacts were established to simulate potentially infectious interactions though occupation, household, and random interactions. Interventions Simulation of standard covid-19 vaccination versus delayed second dose vaccination prioritizing the first dose. The simulation runs were replicated 10 times. Sensitivity analyses included first dose vaccine efficacy of 50%, 60%, 70%, 80%, and 90% after day 12 post-vaccination; vaccination rate of 0.1%, 0.3%, and 1% of population per day; assuming the vaccine prevents only symptoms but not asymptomatic spread (that is, non-sterilizing vaccine); and an alternative vaccination strategy that implements delayed second dose for people under 65 years of age, but not until all those above this age have been vaccinated. Main outcome measures Cumulative covid-19 mortality, cumulative SARS-CoV-2 infections, and cumulative hospital admissions due to covid-19 over 180 days. Results Over all simulation replications, the median cumulative mortality per 100 000 for standard dosing versus delayed second dose was 226 v 179, 233 v 207, and 235 v 236 for 90%, 80%, and 70% first dose efficacy, respectively. The delayed second dose strategy was optimal for vaccine efficacies at or above 80% and vaccination rates at or below 0.3% of the population per day, under both sterilizing and non-sterilizing vaccine assumptions, resulting in absolute cumulative mortality reductions between 26 and 47 per 100 000. The delayed second dose strategy for people under 65 performed consistently well under all vaccination rates tested. Conclusions A delayed second dose vaccination strategy, at least for people aged under 65, could result in reduced cumulative mortality under certain conditions.

Impact of vaccination in reducing Hospital expenses, Mortality and Average length of stay among COVID-19 patients – a retrospective cohort study from India

“…Romero [5] in a simulation based modelling study showed that delaying second vaccine doses for people younger than 65 to prioritize people getting their first dose could reduce mortality.…”

“…The National Vaccination Bureau reported that 0.03-0.04% of persons who have received vaccination could still contract Covid-19(breakthrough infection), although the mortality and ICU stay reduced in them [4]. Further studies from the UK, have shown that even a single dose of vaccination may have a good protective effect [5]. The aim of this study was to study the impact of vaccination on reducing the average length of stay (ALOS), intensive care unit (ICU) requirement, mortality and cost of the treatment among COVID-19 patients.…”

COVID -19 Vaccination in Patients with End Stage Kidney Disease. Early Results for an mRNA Vaccine in a Vulnerable Population

“…Another study evaluated the initial response rate after the first vaccine dose in dialysis patients and reported a response rate of 35% [41], while in a study that evaluated the response rate to vaccination with the BNT162b2 vaccine in a cohort of health care workers, the response rate was 95.5% 14 days after the first dose [42]. Suggestions to delay or skip a second dose of the vaccine have been proposed [43,44], but this strategy may not be appropriate for dialysis patients and other patient groups with lower and/or slower antibody response to vaccination.…”

Analysis of Delayed Vaccination Regimens: A Mathematical Modeling Approach

“…Previous studies have found that the vaccination pace and the efficacy of the vaccine Epidemiologia 2021, 2 272 are the main factors in reducing the number of deaths, number of infected, and hospitalization [17,20,21]. Besides these aforementioned factors, a few researchers have studied the effect of delayed second doses on important health outcomes such as death, among others [6,19,22,23]. Forecasting the long-term dynamics of SARS-CoV-2 in a population is an extremely complex problem due to the great number of variables involved, including the non-pharmaceutical interventions affecting social contacts [24][25][26][27].…”