Covid vaccines this fall ought to goal XBB variant, FDA advisers say

A woman receives a booster dose of Moderna coronavirus vaccine (COVID-19) at a vaccination center in Antwerp, Belgium, February 1, 2022.

Johanna Geron | Reuters

The U.S. Food and Drug Administration’s independent advisory panel on Thursday recommended that updated fall-winter Covid vaccinations target one of the XBB variants that are now out there nationwide the dominant strains of the virus.

The committee voted unanimously that the new vaccines should be monovalent – that is, designed to protect against one variant of Covid – and target one member of the XBB family.

These tribes of Covid are descendants of the Omicron variant that led to a record spike in cases early last year. They are among the strains that have so far eluded the immune system the most.

The consultants also generally agreed that the new shots should specifically target a variant called XBB.1.5. The panel only discussed the specific strain selection and did not vote on it.

According to data from the Centers for Disease Control and Prevention, XBB.1.5 accounted for almost 40% of all Covid cases in the US in early June. This proportion is slowly decreasing and the cases of the related variants XBB.1.16 and XBB.2.3 are increasing.

Consultants noted that XBB.1.5 appears best suited for the fall, as vaccine makers Pfizer, Moderna and Novavax have already started developing vaccines against the strain.

“The 1.5 looks good. It appears that getting to the finish line sooner without the delays and availability is the most feasible,” said Dr. Melinda Wharton, a senior officer at the National Center for Immunization and Respiratory Diseases. “The vaccine we can use is the vaccine we can get. So it seems like a good choice.”

The FDA generally follows the advice of its advisory committees, but is not required to do so. It is unclear when the agency will make a final decision on cultivar selection.

There is also uncertainty about what age groups the FDA and CDC have We recommend that you receive the updated recordings in the autumn.

But the panel’s recommendation is already a win for Pfizer, Moderna and Novavax – all of which conducted initial trials with their respective XBB.1.5 syringes ahead of the meeting.

“Novavax expects to be ready for commercial delivery of a protein-based monovalent XBB-COVID vaccine this fall as well as today [advisory committee] recommendation,” said John Jacobs, the company’s President and CEO.

The US is expected to shift vaccine distribution to the private sector in the fall. That means vaccine makers will start selling their new Covid products directly to healthcare providers and compete for commercial market share.

The panel’s recommendation comes with a broader shift in the impact of the pandemic on the country and the world at large.

The number of Covid cases and deaths has fallen to new lows, governments have rolled back strict health regulations like mask requirements and social distancing, and many people believe the pandemic is finally over.

But dr Peter Marks, head of the FDA’s vaccines division, said the agency was concerned that another wave of Covid would hit the United States “at a time when the virus has evolved, the immunity of the population has continued to wane and we stay indoors in winter.” .”

Updated Covid vaccines, which are regularly updated to target a highly circulating variant, will restore protective immunity to the virus, Dr. David Kaslow, a senior official at the FDA’s Vaccine Division.

This is a similar approach to selecting strains for the annual flu shot. Researchers are assessing the virus strains in circulation and estimating which will be most prevalent in the coming fall and winter.

However, it’s unclear how many Americans will roll up their sleeves to snap the updated shots later this year.

Only about 17% of the U.S. population — about 56 million people — have received the booster shots from Pfizer and Moderna since they were approved in September, according to the CDC.

More than 40% of adults aged 65 and older have been vaccinated by these vaccines, while the rate for younger adults and children is between 18% and 20%.

These boosters were bivalent, meaning they targeted the original Covid strain and the Omicron subvariants BA.4 and BA.5.

Pfizer, Moderna and Novavax shot data

During the meeting, Pfizer, Moderna and Novavax presented preliminary data on updated versions of their vaccines targeting XBB variants.

According to Rituparna Das, the company’s vice president of Covid vaccines, Moderna has been evaluating vaccinations against XBB.1.5 and XBB.1.16 – another transmissible Omicron progeny.

Preclinical study data in mice suggest that a monovalent vaccine targeting XBB.1.5 elicits a more robust immune response against the currently circulating XBB variants than the approved bivalent vaccine targeting BA.4 and BA.5, Das said .

She added that data from clinical trials in more than 100 people also shows that the monovalent XBB.1.5 vaccine produces protective antibodies against all XBB variants. All study participants had previously received four doses of the Covid vaccine.

Das said that overall protection against XBB strains was likely due to the lower number of unique mutations between the variants, meaning their composition was similar.

According to Darin Edwards, head of Moderna’s Covid vaccine program, there are only three unique mutations between the XBB.1.5 and XBB.1.16 variants. In comparison, there are 28 mutations between Omicron BA.4 and BA.5.

That means the immune response elicited by an updated vaccine against XBB variants will likely be similar regardless of which specific variant it targets, Edwards said.

Pfizer also presented early study data suggesting that a monovalent vaccine targeting an XBB variant provides enhanced immune responses against the XBB family.

The company laid out specific timelines for making an updated vaccine available, depending on the strain that the FDA chooses.

According to Kena Swanson, the company’s Chief Scientist, Pfizer will be able to deliver a monovalent shot against XBB.1.5 by July and a sting against XBB.1.16 by August.

Pfizer won’t be able to release a new vaccine until October if the FDA chooses a completely different strain, Swanson said.

Novavax did not provide a specific timeline for delivering a shot aimed at XBB.1.5, but noted that an XBB.1.16 shot would take eight weeks longer.

Novavax presented preclinical study data indicating that monovalent vaccines against XBB.1.5 and XBB.1.16 elicit stronger immune responses to XBB subvariants than bivalent vaccines.

according to dr Filip Dubovsky, Novavax’s Chief Medical Officer, the data also shows that an XBB.1.5 syringe produces antibodies that block XBB.2.3 from attaching to and infecting human cells.

Dubovsky said the trial results support the use of a monovalent XBB.1.5 vaccine in the fall.

The Novavax vaccine uses protein-based technology, a decades-old antiviral method used in routine hepatitis B and shingles vaccinations.

The vaccine works differently than Pfizer and Moderna’s messenger RNA vaccines, but achieves the same result: It teaches your body how to fight Covid.

Comments are closed.