Effectiveness of AstraZeneca’s COVID–19 vaccine increases with a 3 months gap before the second dose: AstraZeneca and Oxford have claimed that their vaccine was more effective with a 3 – 3-month gap before the second dose. This was revealed in a peer–reviewed study in a medical journal called The Lancet on 19 February 2021.
Initially, the second dose was administered six weeks after the first dose, and the efficacy was found to 55.1 %. However, when the second dose of the vaccine was given 3 months after the initial dose, the efficacy rose to 81.3 %. As per the researchers involved in this study, this extended dosage regimen can benefit the patients. They believe that this regimen will help sort out the limited supply of the vaccine. Apart from this, the researchers also claimed that this would allow for rapid immunization of a large population in the countries.
This study also validated the previous findings of the company’s vaccine. The previous finding showed that the vaccine has an efficacy of 76 % against symptomatic patients for up to 3 months after the initial dose. This was revealed at the beginning of February 2021. Despite these findings, the scientists remain unsure of the exact duration for which the protection of a single dose of the vaccine can last. This is attributed to the fact that the trials can only be limited to 3 months period, and hence the scientists recommend a second dose.
About the study:
This recent study was done to understand the effect of the different intervals on the protection offered after the second dose is given. The risk of infection between the two doses’ administration was also analyzed in this study. These changes could be due to the first dose’s lower effectiveness; or the rapid declining effect while waiting for the second dose. The data collected from over 17,178 participants in the United Kingdom, Brazil, and South Africa were used for this purpose.
The World Health Organization has also approved AstraZeneca’s COVID–19 vaccine for emergency use in the third week of February 2021. This, in turn, has paved the way for the distribution of this vaccine to developing countries through the COVAX program.