Daily Management Review

Study Finds Increasing Gap Between Gap Of Two Covid-19 Vaccines Can Help Reduce Deaths


A predictive modelling study has revealed that a delaying of the second dose of a Covid-19 vaccine for people who are younger than 65 years could help in reducing the number of people dying of the disease.
Even as the Covid-19 pandemic is continuing in many parts of the world, the debate of increasing the gap between the two doses so that as many people as possible are administered at least the first dose to give them some immunity or to continue with the predetermined intervals between two doses has also emerged.
Pfizer has said for example, that it did not have any clinical evidence that can support the decision of the British government to widen the gap between doses of its vaccine to 12 weeks. However, data determined from the rollout of Covid-19 vaccines in England has shown that the first dose administration has resulted in giving people an 80 per cent protection against death from the disease as well as a 70 per cent drop in infections.
A series of scenarios for forecasting the potentially infectious interactions under different conditions was ram by researchers of the U.S. study which was published in the BMJ British medical journal, using a simulation model based on a "real-world" sample of 100,000 U.S. adults.
The scenarios included different levels of vaccine efficacy and immunisation rates as well as different assumptions about whether transmission and serious symptoms are prevented by vaccines or whether it only helps to prevent serious symptoms, including death.
"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," wrote the researchers, led by the Thomas C Kingsley of the Mayo Clinic in Rochester, Minnesota.
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.
No optimum schedule was recommended in the study.
"Decision makers will need to consider their local vaccination rates and weigh the benefits of increasing these rates by delaying a second dose versus the risks associated with the remaining uncertainty in this strategy," the team said.
Separately, an Oxford University-led study on giving shots from different manufacturers for the two doses reported its first findings - on the frequency of common post-vaccination symptoms such as sore arm, chills or fatigue.
According to the results of the study, there was more likelihood of reporting of mild or moderate symptoms such as headaches or chills from people who were administered two doses of separate vaccines – one form Pfizer and the other of AstraZeneca, compared to those people administered two doses of the same vaccine.
The two vaccines that were the first to be available in Britain were the Pfizer and AstraZeneca vaccines that were used for the “mix-and-match” study. Tghat research has recently added vaccines of Novavax and Moderna.