Increased Dose Interval for Covishield


In the ongoing Covid-19 vaccine campaign, the health ministry has agreed to extend the period between the first and second doses of Covishield to up to eight weeks.


This decision was made based on the results of AZD122’s global trials, which indicate that increasing the dosage length to 12 weeks improved the drug’s efficacy significantly. The vaccine had an efficacy of 79 percent even though the second dose was administered four weeks after the first dose, according to interim results from trials in the United States, Chile, and Peru.

What do the experts advise?

On the advice of two expert groups, the National Technical Advisory Group on Immunization (NTAGI) and the National Expert Group on Vaccine Administration for Covid-19, the Ministry of Health and Family Welfare has decided to raise the dose interval (NEGVAC).The groups looked at the experimental evidence from Covishield vaccine clinical trials and came to the conclusion that the vaccine’s safety is improved if the second dose is given between 6 and 8 weeks after the first.

Some countries’ reports

According to a study on AZD1222 vaccine trials from other nations, the vaccine’s effectiveness was improved when the second dose was given six weeks after the first dose. During a phase 3 clinical trial in Brazil, the UK, and South Africa, the efficacy of the vaccine AZD1222 was about 54.9 percent when the second dose was given after a delay of less than six weeks.The vaccine’s effectiveness improved to 59.9% when the second dose was administered 6-8 weeks after the first dose, according to the study. When the second dose was given after a 9-11 week break, it increased to 63.7 percent, and when the period was increased to 12 weeks or more, it increased to 82.4 percent.

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