AstraZeneca recipients should get different vaccine brand as booster shot — NVOC

The National Vaccination Operations Center (NVOC) has advised healthcare workers who were inoculated with the AstraZeneca vaccine for the primary series to get a different brand as a booster dose.

The NVOC said in a memorandum that there is a "theoretical possibility of pre-existing immunity attenuating or weakening the immune response on the second or third dose" for vector-based vaccines such as AstraZeneca. 

Recipients of the AstraZeneca vaccine may be vaccinated with Pfizer and Moderna for their booster doses. They must wait for six months after the completion of their primary series before getting booster shots.

However, Dr. Edsel Salvana of the Department of Health-Technical Advisory Group stressed that this was only a "theoretical risk."

“There is one study that says this does not seem to be the case. It’s really more of a theoretical risk. When we’re talking about boosters, there are really just two things we’re talking about: safety and efficacy,” Salvana said at the DOH town hall meeting. 

“From a safety standpoint, there doesn’t seem to be any problems with the third dose of Astra. The question then becomes efficacy,” he added.

Salvana said the adenovirus carrier of the booster shot may be unable to deliver its viral material into the cell by the third dose due to preformed antibodies.

“This may also hold true, again theoretical, with the other adenovirus vaccines like Jannsen and Gamaleya,” he added.

The Philippines on Wednesday began the inoculation of fully vaccinated healthcare workers with booster doses. — VBL, GMA News