Health officials are considering whether New Zealanders should receive booster shots as the Delta outbreak continues.
Speaking with RNZ's Morning Report, Bloomfield said officials are considering booster injections for those who received their Pfizer vaccines at the start of the year.
Israel and the United States are among countries providing booster shots to certain people who have compromised immunities.
Act leader David Seymour asked the Health select committee about booster shots this afternoon.
Professor Nikki Turner, of the University of Auckland, said the evidence on when boosters would be needed was unclear.
"We are expecting at some stage we will need boosting, but we do not know when."
The Science Media Centre New Zealand spoke with a number of national and international experts on the topic of booster shots.
New Zealand's Dr Fran Priddy believes the country's priority is vaccination, but said booster shots aren't "unrealistic".
"Right now the priority is to get as many people as possible in New Zealand vaccinated with their primary series, particularly focusing on groups at higher risk such as Māori, Pasifika and the elderly, and ensuring vaccination is accessible," she said.
"If we begin to move more quickly on vaccinating all at a national level, and there is sufficient vaccine supply, it is not unrealistic to then also consider the need for boosters."
Priddy said more data would help officials make an informed decision on boosters.
Yesterday, Prime Minister Jacinda Ardern said there was a lot of discussion and debate around booster shots but no clear conclusion yet.
"There's still a lot of debate among the experts and the immunologists over the role of booster shots so we are watching that evidence and following closely."
Jesse L. Goodman, a Professor of Medicine at Georgetown University in the US said two things are driving the consideration of booster shots.
"One, we're seeing the levels of antibody that vaccinated patients have decline over time, which can sometimes signal a loss in protection.
"But number two, more important, we're seeing that the protection against overall infections is also declining," he said.
But he said the question was whether the booster shoots effect hospitalisation, severe disease and death.
Dorry Segev, Professor of Surgery and American Epidemiology, believes a booster shot may be required every year.
However, as the virus evolves and new strains appear he believes new vaccine will appear.
"I have little doubt that at least once a year we're going to be getting boosters for this virus, either in the form of new vaccines that cover new variants or boosters that take our decreased immune response and help it regain some protection."
But he said boosters are "the same vaccine over again".
"If our immune system has decreased to the vaccine we got, we can give more vaccine and our immune response increases.
"Ultimately I think what will happen is the variants will change to the point where we need new formulations of the vaccine," he said.