People who require a third primary dose of a COVID-19 vaccine may also need to get a booster shot, according to Chief Medical Officer Dr Roshan Parasram on Wednesday.
Responding to a question from Guardian Media during the Ministry of Health’s virtual press conference, Parasram explained that a third primary dose is different from a booster shot.
“The primary additional dose is meant to get your primary series up to a point where the immunity that you have is considered adequate and it’s usually done to augment to primary additional series for certain instances. For example, in the immunocompromised population, those who are moderately/severely so. The difference between that and the booster programme, again is really an augmentation of a primary series to bring you up to what the level of someone else who is not immunocompromised would have had,” he said.
He said while there isn’t yet the data to back a fourth shot as a booster in these instances, it’s likely it would be needed.
“The data is still out but at least from a theoretical perspective, if you have an additional primary dose making your series complete it will therefore mean that you will need an additional shot as a booster,” he said.
“In terms of timeline, it will probably align with what is going on now meaning six months (after the third primary dose) for most vaccines two to six months for the Johnson and Johnson vaccine.”
—Rishard Khan