Since the beginning of the Covid-19 pandemic, variants and subvariants of the SARS-CoV-2 virus have branched out repeatedly. Now, vaccine manufacturers may begin creating booster vaccines that include components to fight the multiple dominant Omicron subvariants currently gaining ground in the United States.
The announcement comes from the U.S. Food and Drug Administration (FDA) two days after the FDA’s Independent Vaccines, and Related Biological Products Advisory Committee met to discuss if an updated Covid-19 booster vaccine that includes an omicron-specific component should be recommended, reports Jen Christensen for CNN. The panel of independent scientists and physicians endorsed an updated Omicron subvariant vaccine by a 19-2 vote, reports Carolyn Y. Johnson for the Washington Post.
The FDA hopes the modified Covid-19 vaccines could start being administered early to mid-fall, when public health experts expect another wave of infection as immunity from previous vaccines and infections wane, the weather cools and individuals spend more time indoors, reports Spencer Kimball for CNBC News. Scientists suspect that redesigned boosters may provide a broader range of immune responses and possibly protect against future emerging variants, Reuters reports. New vaccines would simply be a booster to those who are already fully vaccinated, similar to annual flu vaccinations, CNN reports.
The first round of Covid-19 vaccines have provided robust protection, especially against severe illness, for at least six months after immunization. However, natural waning of the protection provided by vaccines occurs. And Omicron subvariants BA.4, and BA.5 can elude some antibodies produced after coronavirus vaccination and infections, reports Adeel Hassan for the New York Times. BA.4 and BA.5 combined now account for more than 50 percent of infections in the United States, according to Centers for Disease Control and Prevention (CDC) data.
Vaccine manufacturers are having trouble keeping up with the rapid evolution of the virus since it seems to evolve faster than clinical trials involving humans can deliver results, report Sharon LaFraniere and Noah Weiland for the New York Times. No one knows what variants will dominate in the fall or if more may arise, but the FDA is leaning towards a vaccine formulation that combines the existing vaccine, which is based on the original, wild-type virus that began the pandemic, with one tailored to BA.4 and BA.5, per the New York Times. Experts are also aiming for broader protection against Covid-19 rather than sticking to a vaccine made for the wild-type strain that is no longer prominent in circulation.
“I still think there’s value in increasing the breadth of immunity, and I will reiterate that we’re not trying to match what may circulate,” says Kanta Subbarao, a virologist at the World Health Organization Collaborating Center for Reference and Research on Influenza to CNN. “It is not so much to match what is likely to circulate because there’s so much uncertainty about the trajectory of this evolution. We’re trying to increase the breadth of the immune response without losing the benefit from the ind’x vaccine that's performed so well."
Pfizer/BioNTech and Moderna have already developed updated shots to target Omicron variant BA.1. Their data shows superior antibody responses against the Omicron variant, reports Matthew Herper for STAT News. Pfizer/BioNTech presented data that showed their two vaccine boosters targeting Omicron had a higher immune response than their current Covid-19 vaccine, and preliminary lab studies showed the updated booster could neutralize BA.4 and BA.5, per CNN. Moderna presented data on its bivalent (meaning it targets two different strains, BA.4 and BA. 5) Covid-19 vaccine booster dubbed mRNA-1273.214, which also showed a potent response against subvariants.
However, if authorized by the FDA, new boosters tailored to Omicron BA.4 and BA.5 may have slow roll outs as vaccine manufacturers are currently producing boosters targeting BA.1 and need to switch over, Reuters reports.
Kathrin Jansen, head of vaccine research for Pfizer, told the New York Times that regardless of which formulation the FDA chooses to use, they will be ready to deliver doses in early October. In contrast, Stephen Hoge, the president of Moderna, said that their company could provide quantities by late October or early November if no additional clinical data requirements are needed.