KOCHI: What should be the ideal gap between two jabs of Covishield? Whether the interval of four-six weeks between two jabs or 10-14 weeks is better is the most frequently asked question. A Kochi-based research centre that carried out a study says the longer the gap between two jabs, the better the antibody levels. The study was done by clinical immunologist and rheumatologist Dr Padmanabha Shenoy and his team at CARE to understand the ideal gap between the two jabs.
“Evidence suggests that extended vaccine jab intervals provide higher antibody levels which are likely to last for a longer time,” said Dr Shenoy. For the study, 213 patients with rheumatic diseases were selected to observe who developed better immunity against Covid infection depending on the gap between two jabs. The selected group was followed up to assess their immune response.
Till May, the interval between two doses was four to six weeks. Thus, a group of 102 persons who received both doses within the said gap were selected. In another group, 111 patients who were inoculated after the policy change -- ie; the gap increased to 10-12 weeks -- were included.
“On observing the anti-spike antibody of both groups after a month of the second dose, we found that patients who took vaccines at an interval of 10-14 weeks acquired about a 3.5-fold increase in antibody levels as compared to patients who took vaccines at an interval of 4-6 weeks (879 vs 255),” said Dr Shenoy.
A similar study was conducted at the University of Birmingham in the UK with the Pfizer vaccine as well. One of the probable reasons for the current spike in Covid cases in the US and Israel is the shorter vaccination intervals. On the contrary, better performance in the UK may be because of extended vaccine intervals, as claimed by some health experts.
“On the other hand, we know that the single dose of the vaccine does not offer much protection from the Delta variant. Due to this, there is an increasing concern that by delaying the second dose, we are making a person who had the first dose susceptible to getting Covid infection during the period between doses.
“What we need is a trade-off between early but short-lasting immunity v/s late long-lasting immunity. At a societal level, it appears that a longer gap is desirable as it will give longer-lasting protection. But should the gap between jabs be limited to a maximum of eight weeks, or can it be extended to 12 weeks? This needs to be studied further,” Shenoy added.
Bridging the gap
The study was done by clinical immunologist and rheumatologist Dr Padmanabha Shenoy and his team to understand the ideal gap between the two jabs.