Long delay between  AstraZenaca jabs is beneficial – study

Studies show that the AstraZeneca vaccine-induced immunity for at least a year after a single dose and strong immune responses after a late (up to 10 months) second dose – good news for countries with low supplies.

This is demonstrated by the results of a sub-analysis of the COV001 and COV002 trials published by the University of Oxford on The Lancet’s prepress server, which included volunteers aged 18 to 55 years who were enrolled in the COV001 and COV002 trials and had received a single dose or two doses of the covid-19 AstraZeneca vaccine.

The University of Oxford said in a statement, that a prolonged interval between the first and second doses of AstraZeneca’s covid-19 vaccine of up to 45 weeks resulted in an up to an 18-fold increase in antibody response, measured 28 days after the second dose.

“With a 45-week dosing interval between the first and second doses, the antibody titers were four times higher than with a 12-week interval, showing that a longer dosing interval is not harmful, but can generate stronger immunity, “it said.

The analysis further highlighted that a third dose of AstraZeneca’s covid-19 vaccine given at least 6 months after a second dose increased antibody levels six-fold and maintained the T-cell response. A third dose also resulted in a greater neutralizing activity against the Alpha (B.1.1.7, ‘Kent’), Beta (B.1.351, South African), and Delta (B.1.617.2, Indio) variants.

Both the late second dose and the third dose of AstraZeneca’s covid-19 vaccine were less reactogenic than the first dose, Oxford University commented.

“This should be reassuring news for countries with lower vaccine supplies, which may be concerned about delays in supplying second doses to their populations. There is an excellent response to a second dose, even after a 10-month delay from the first, ”said Professor Sir Andrew J Pollard, Senior Investigator and Director of the Oxford Vaccine Group at the University of Oxford.