march 2021 • NEJM

Delayed Second Dose versus Standard Regimen for Covid-19 Vaccination

Kadire S., et al

DOI: 10.1056/NEJMclde2101987

Content curated by:David Rodrigues

Key message

This articles summarizes arguments for two approaches on vaccination strategies: keeping standard regimen or delaying the second dose. The following section is quite relevant: "Under normal circumstances, the vaccines should be deployed in keeping with the trial protocols. However, the current circumstances — a slow vaccine rollout, a limited vaccine supply, and the recent emergence of more infectious SARS-CoV-2 variants that threaten to outpace our vaccination program — are anything but normal. This may be a case in which the risks of strict adherence to the plan outweigh the risks of modifying it. Some argue that any deviation from the protocol used in the clinical trials is unscientific. But the argument is based on an overly narrow definition of science. In both trials, the cases in the placebo and active vaccine groups began to diverge about 10 days after the first dose, with growing vaccine efficacy over time. By the day of the injection of the second dose, the efficacy of the first dose was somewhere in the range of 80 to 90%."


A Task Force on Administration of Covid-19 Vaccine You chair the Governor’s task force on rollout of the Covid-19 vaccine. Given concerns about the limited availability of the two-dose mRNA vaccine, you have been asked to weigh in on the debate regarding the most effective use of the currently available doses. Should people who have already received a first dose of vaccine have their second dose delayed by a number of months until there is a greater supply, so that more people can receive a first dose? Or should those who have gotten the first dose receive the second dose according to the standard schedule, 3 to 4 weeks after the first dose, as recommended by the Food and Drug Administration (FDA)? You must consider the benefits and risks of the two approaches, on both individual and population levels, and decide what to recommend to the task force.