Proportions of two new Omicron subvariants, XBB.1.16 and XBB.1.9.1, continued to rise this week, the Centers for Disease Control and Prevention (CDC) said today in its latest estimates. XBB.1.16, which is thought to have a growth advantage and immune escape properties, now makes up 11.7% of viruses, up from 7.4% the week before. Levels are greatest in the South Central, Middle Atlantic, and Northwestern parts of the country.

Meanwhile, the XBB.1.9.1 proportion increased from 7.4% to 9% over the past week, with levels highest in the region that includes Iowa, Kansas, Missouri, and Nebraska, where it makes up an estimated 23.9% of samples.

So far, the United States isn't experiencing any rises in COVID-19 markers, all of which continue to decline slowly, according to CDC data. The CDC recorded 88,330 cases and 1,052 deaths for the week ending April 26. The 7-day average for new COVID hospitalizations is 1,510, down 16.4% compared to the previous 7-day average.

The Food and Drug Administration (FDA) this week announced the approval of the first fecal microbiota that can be taken orally for the prevention of recurrent Clostridioides difficile infection (CDI) in people ages 18 and older following antibacterial treatment for the condition.

The product, called Vowst and made by Massachusetts-based Seres Therapeutics, contains live bacteria from human fecal matter donated by qualified people. Patients take four capsules once a day for 3 consecutive days.

In an April 26 statement, Peter Marks, MD, PhD, who directs the FDA's Center for Biologics Evaluation and Research, said, "The availability of a fecal microbiota product that can be taken orally is a significant step forward in advancing patient care and accessibility for individuals who have experienced this disease that can be potentially life-threatening."

C diff is one of the nation's most common healthcare-associated infections and is linked to 15,000 to 30,000 deaths each year. Antibiotic treatment can change the microorganisms in the gut, and other factors such as increased age and living in a nursing home can increase the risk of CDI. Treatment options are limited, but administering fecal microbiota is thought to restore gut flora to prevent more CDI episodes.

The approval follows the February publication of results from an arm of a phase 3 clinical trial, which found that the microbiome therapy, formerly called SER-109, was well tolerated and showed clinical benefit. The investigators concluded that data supports an important role for the drug as part of a paradigm shift in treating recurrent CDI.

The FDA noted that the most common side effects were abdominal bloating, fatigue, constipation, chills, and diarrhea. When the company applied for licensing, the FDA granted it priority review, breakthrough therapy, and orphan drug designations. In 2021, Seres and Nestle Health Science signed an agreement to jointly market the therapy in the United States and Canada. In December 2022, the FDA approved the first fecal microbiota preventive for CDI, Rebyota, which is given by enema.

Two countries—the Democratic Republic of the Congo (DRC) and Madagascar—reported more polio cases this week, all involving vaccine-derived strains, the Global Polio Eradication Initiative (GPEI) said in its latest weekly update.

In the DRC, officials reported 15 circulating vaccine-derived poliovirus type 1 (cVDPV1) cases from three different provinces. Three are included in the 2022 total, and 12 are part of this year's total, which is now 12. Also, the country had 21 more circulating vaccine-derived poliovirus type 2 (cVDPV2) cases from seven different provinces. Two were added to its 2022 total, and the rest are included in its number for this year, which now stands at 19.

Elsewhere, Madagascar reported four cVDPV1 cases, lifting its total this year to nine. Of the new cases, one was from Androy, and three were from Analamanga.