Vaccine experts reject proposal to shorten interval between doses of Sinovac, AstraZeneca jabs

MANILA, Philippines — The Philippines’ vaccine expert panel on Thursday thumbed down a proposal to shorten the interval between the first and second dose of the COVID-19 vaccines, especially from Sinovac and AstraZeneca.

Dr. Nina Gloriani, Vaccine Development Expert Panel Head. Screengrab from Laging Handa briefing

Doing so will decrease the antibody response and lower the vaccines’ efficacy, the head of the Department of Science and Technology’s vaccine expert panel Dr. Nina Gloriani said in an online Palace briefing.

“We have very good data on that na hindi po pupuwedeng shorter ang interval… We saw that when we were evaluating the (Sinovac) vaccine, ang baba talaga ng zero conversion and GMT (geometric mean titer) doon sa 14 days versus the 28 days. In fact, if you prolong it baka better pa (it may give better protection),” she noted.

“‘Yun pong very specific na-mention, yung Sinovac gusto nila maging 14 days [interval]. Actually, we have data, yung 14 days versus 28 days, mas mababa po yung mga antibody responses doon,” Gloriani added.

(They want Sinovac doses to be administered between 14 days. On 14 days, the antibody response is lower than on 28 days.)

Meanwhile, Gloriani said studies have shown that the AstraZeneca vaccine is more effective if the second dose is prolonged to 12 weeks after the first dose.

“Sa AstraZeneca, it has very clear data that when you prolong the interval between doses, not just for the first and second dose but pwedeng sa second and third, you actually generate more and better immune responses,” she said.

(There is very clear data saying that when you prolong the interval between AstraZeneca doses, not just for the first and second dose but also for the second and third, you actually generate more and better immune responses.)

Gloriani said the same goes for “most vaccines” where a longer interval between the two doses meant higher levels of antibodies.

VEP member Dr. Rontgene Solante shared the same sentiment. “We cannot afford shortening the interval from 28 to 14 days kasi medyo dehado tayo sa efficacy ng bakuna (because we will lose higher efficacy of the vaccine),” he said.

An OCTA Research fellow earlier urged the government to shorten the interval between administering two doses of Sinovac and AstraZeneca COVID-19 vaccines. OCTA made this proposal in order to protect people better against the Delta variant of COVID-19.

READ: OCTA urges gov’t to shorten interval for Sinovac, AstraZeneca doses

Molecular biologist Fr. Nicanor Austriaco believed this will speed up the process of vaccination to protect more people from the Delta variant.

EDV/AC