The vaccine’s ability to prevent infection ranged from 39% to 84% since the introduction of the Delta variant.
“Vaccines remain effective in preventing hospitalization and severe disease but might be less effective in preventing infection or milder symptomatic illness,” the presentation said.
The slides said both waning protection over time and the Delta variant may be contributing to the lower effectiveness of the vaccines.
Oliver said it’s not uncommon for some vaccines to require multiple doses, including vaccines for hepatitis and HPV. However, she said more information is needed before the group can assess the need for booster shots.
Experts have warned that the spread of the virus, specifically the Delta variant, could lead to a more dangerous variant.
“This is a very wily virus,” Fauci said. “If we keep lingering without getting those people vaccinated that should be vaccinated, this thing could linger on, leading to the development of another variant, which could complicate things.”
Those most at risk of severe disease should be prioritized for booster shots, the presentation added.
Oliver also said it’s important to ensure there is global vaccine availability. “Uncontrolled spread globally that could result in new variants threaten control of the pandemic everywhere,” her presentation said.