By Nneka Nwogwugwu
Giving a first dose of COVID-19 vaccine but delaying a second dose among people younger than 65 could lead to fewer people dying of the disease, a U.S. study, published in the BMJ British medical journal revealed.
As the coronavirus pandemic continues, there is debate over whether to extend the gap between doses to give as many people as possible some protection, or stick to the intervals designated in clinical trials.
For example, Pfizer (PFE.N) has said there is no clinical evidence to support Britain’s decision to extend the gap between doses of its vaccine to 12 weeks, but data from the rollout in England shows protection against death of around 80% from one dose, with a 70% decline in infections.
According to the study published by Reuters, the researchers used a simulation model based on a “real-world” sample of 100,000 U.S. adults and ran a series of scenarios to forecast potentially infectious interactions under different conditions.
These included varying levels of vaccine efficacy and immunisation rates, and varying assumptions as to whether the vaccine prevents transmission and serious symptoms or only prevents serious symptoms, including death.
Researchers, led by the Thomas C Kingsley of the Mayo Clinic in Rochester, Minnesota, wrote, “The results suggest that under specific conditions a decrease in cumulative mortality, infections, and hospital admissions can be achieved when the second vaccine dose is delayed.”
The specific conditions include having a vaccine with a one dose efficacy of at least 80% and having daily immunisation rates of between 0.1% and 0.3% of a population – but if they are met, a delayed second-dose strategy could prevent between 26 and 47 deaths per 100,000 people compared to the usual schedule.
However, the study did not recommend an optimum schedule.
