While there is no evidence that people immunized with either vaccine offer less protection against the variants, both companies said they have begun to look for ways to account for evolving mutations.
Particularly troubling is the B.1.351 variant first seen in South Africa. It carries a mutation that helps it evade the body’s immune response to infection. The B.1.1.7 variant first seen in the UK is also a cause for concern as the mutations appear to make it more transmissible, so it spreads better and it can cause more serious illness as well.
Researchers are also finding variants in the US that have evolved mutations that help them bypass the immune system.
Pfizer and its partner BioNTech said on Thursday they have begun testing how well adding a third dose of their authorized vaccine can protect against new variants.
The study will look at the safety and immune response of a booster dose in up to 144 participants of the earlier Phase 1 study in the US, including a subgroup of older adults up to age 85. It will also involve testing how well their antibodies are able to neutralize “stresses of interest” in the lab, the companies said.
Volunteers would receive a third dose between 6 and 12 months after their previous two doses. The dosage would be identical to what is currently allowed: 30 micrograms.
“This booster study is critical to understanding the safety of a third dose and its efficacy against circulating strains,” said Pfizer CEO, Dr. Albert Bourla in a statement.
Separately, Pfizer and BioNTech are also “in ongoing discussions with regulatory authorities” about the possible testing of a vaccine that has been modified to protect against affected variants in a Phase 1/2 study.
Bourla noted, however, that the companies have not yet seen conclusive evidence that variants are resistant to the vaccine, although they are taking steps to be prepared.
Moderna said late Wednesday on Wednesday that it has produced an updated version of its Covid-19 vaccine to help it combat the B.1.351 variant first seen in South Africa. The first doses have been sent to the National Institutes of Health for a clinical study.
The new vaccine, called mRNA-1273351, will be evaluated as a booster shot for people who have already been vaccinated against the coronavirus and as a primary vaccine for people who have not had a coronavirus and are yet to be vaccinated.
Moderna said it will also evaluate a “multivalent” booster shot that combines the new vaccine formulation with the current vaccine.
In addition, the company said it has begun to test whether a third, lower dose of the current Covid-19 vaccine can boost immunity to worrisome variants of coronavirus, with some study participants already receiving a third dose.
“We are rapidly testing updates to the vaccines that address emerging variants of the virus in the clinic. Moderna is committed to updating our vaccine as often as possible until the pandemic is under control. We hope to demonstrate that booster doses, if needed, it can be done at lower dose levels, allowing us to deliver many more doses to the global community by the end of 2021 and 2022, if needed, ”said Stephane Bancel, Moderna’s CEO in a statement.
Moderna has not said how long it expects the studies to last, or when the new vaccine would be available, if allowed. The current vaccine requires two doses of 100 micrograms approximately one month apart. The new booster doses are evaluated at half that level and below.
On Monday, the U.S. Food and Drug Administration announced new guidelines that streamline and accelerate the process of updating vaccines to target variants. An agency official estimated that this could involve several hundred people and take several months.
“It will be on the order of a few hundred individuals in size and we expect that could take a few months,” said Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, during a call with reporters on Monday.
The vaccine from both Moderna and Pfizer uses a new technology that uses messenger RNA or mRNA that simply requires a genetic code. The design is intended to update the vaccines quickly, without the months of preparation required to change a flu vaccine, for example.