The World Health Organization (WHO) recently published its initial risk assessment of the Omicron XBB.1.16 subvariant, which followed a meeting last week of its technical advisory group on virus evolution. Based on the assessment, the WHO on Apr 20 said it elevated XBB.1.16 from a variant under monitoring to a variant of interest.

XBB.1.16 has a similar genetic profile as XBB.1.5. First reported in January, XBB.1.16 has now been detected in 33 countries, with most sequences from India, the United States, Singapore, Australia, Canada, Brunei, Japan, and the United Kingdom.

So far, no changes in severity have been reported. XBB.1.16 doesn't seem to come with additional health risks compared to XBB.1.5, but it may become dominant in some countries owing to its growth advantage and immune escape properties.

India and Indonesia have reported slight increases in hospital bed occupancy, but at levels much lower than in previous waves. Information from India points to no differences in hospitalization or the need for supplemental oxygen compared to other circulating lineages.

The WHO said the overall risk is low. The level of confidence in the data showing an increased growth advantage is high, but it's low for the antibody escape data. The WHO said its confidence in the data pointing to no increased severity is moderate.

Shielding, a public health strategy used across the United Kingdom in the early months of the pandemic, aimed to keep the most vulnerable citizens protected from the novel coronavirus at home and away from public-facing jobs and schools. But a new study of Welsh citizens published in the May issue of Public Health shows the strategy did little to prevent infection in this group.

"Our study found no evidence of reduced COVID-19 infections one year after shielding was introduced. This raises questions about the benefits of shielding for vulnerable people as a policy," said lead author Helen Snooks, PhD, of Swansea University Medical School in a press release.

Our study found no evidence of reduced COVID-19 infections one year after shielding was introduced.

The study compared outcomes, including infection, deaths, and admissions to hospitals and intensive care units among a cohort of 117,415 shielded people, with 3,086,385 citizens who were not shielded during the first year of the pandemic in Wales. The shielded population included cancer patients (18.6%), those on immunosuppressive therapy (25.9%), and those with severe respiratory conditions (35.5%). All information came from anonymous electronic health records.

An 'untested public health policy'

People who were shielded were more likely to be residents in long-term care facilities, women, and those ages 50 and older.

Shielded people had a slightly higher known infection rate—5.9% versus 5.7%—compared with controls. All outcomes of infection were worse among shielded people. They were more likely to die (odds ratio [OR], 3.68), have a critical care admission (OR, 3.34), hospital emergency admission (OR, 2.88), and visit the emergency department (OR, 1.89) compared with unshielded Welsh citizens.

"Shielding was an untested public health policy that was introduced in the United Kingdom early in the pandemic, in contrast to other countries where there was more focus on closing borders, lockdown, test and trace systems," the authors concluded. "The shielding policy was based on assumptions rather than evidence of effectiveness."

Equatorial Guinea's health ministry yesterday reported another Marburg virus case, involving a person who died from his or her infection. On Twitter, officials said the patient is a relative of someone from the city of Bata whose infection was confirmed on Apr 6.

The country, like Tanzania, is currently battling its first Marburg virus outbreak. The latest case lifts Equatorial Guinea's number of confirmed infections to 17, which includes 12 deaths. The country has also reported 23 probable cases, all fatal. Officials are monitoring 116 contacts.

Confirmed cases have been reported across four Equatorial Guinea provinces, with several from Bata, the country's largest city that is home to a port and an international airport. Like Ebola virus, Marburg virus spreads among humans through contact with infected body fluids and has a high case-fatality rate.

An analysis of stool samples from patients in Mozambique, nearly half of whom had HIV, found high rates of antibiotic resistance in diarrheal pathogens, researchers reported late last week in BMC Infectious Diseases.

In the study, researchers from Mozambique and the United States conducted antibiotic susceptibility testing on 157 stool isolates recovered from 129 patients at two health centers, including 68 HIV infected and 61 uninfected individuals. The isolates, which consisted of 99 Salmonella, 45 Shigella, and 13 Campylobacter strains, were tested against six antibiotics on Mozambique's national essential medicines list.

All isolates drug-resistant

All isolates were resistant to at least one antibiotic, with the vast majority of Salmonella and Shigella isolates resistant to trimethoprim-sulfamethoxazole (89.9% and 86.6%, respectively). In addition, most Salmonella isolates were resistant to erythromycin (88.9%) and tetracycline (76.8%), most Shigella isolates were resistant to tetracycline (68.9%), and most Campylobacter isolates were resistant to erythromycin, azithromycin, and tetracycline (92.3% for all three antibiotics). Multidrug resistance was observed in 79.8% of Salmonella, 76.9% of Campylobacter, and 57.8% of Shigella isolates.

Drug susceptibility profiles for Salmonella and Campylobacter were similar in HIV-infected and uninfected patients, but Shigella isolates from uninfected patients were significantly more likely to be resistant to erythromycin or azithromycin or exhibit multidrug resistance.

The high prevalence of antibiotic resistance findings in this study is likely due to multiple factors.

The study authors say the high rate of resistance to trimethoprim-sulfamethoxazole is particularly concerning, since it is often the treatment of choice for patients with diarrhea and is used as prophylaxis for opportunistic infections in HIV patients.

"Overall, the high prevalence of antibiotic resistance findings in this study is likely due to multiple factors, including unrestricted and inappropriate use of antibiotics through self-medication, the sale of antibiotics in informal markets, cross-contamination through environmental and food sources, and the use of antibiotics in animal husbandry without proper guidance from healthcare professionals," the study authors wrote. "Our results highlight the critical need for implementing measures to promote responsible antibiotic use in both human and animal populations."

Researchers with the Israeli Phage Therapy Center (IPTC) reported last week in Open Forum Infectious Diseases that 78% of compassionate-use bacteriophage treatments given to patients since 2018 have resulted in a favorable outcome.

Since being established in 2018 by the Hadassah Medical Center and the Hebrew University of Jerusalem, IPTC has received 159 requests for compassionate use of phage therapy for previously failed infections—145 from Israel and the rest from the United States, Finland, and Germany. Because there is no standardization on authorization or approval of phages, which are bacteria-specific viruses that have emerged as a promising therapy for antibiotic-resistant infections, all phage therapy treatments are considered compassionate therapy.

Bone and respiratory infections were the most common indications for phage requests, and the most common bacteria were Pseudomonas aeruginosa, Acinetobacter baumannii, and Staphylococcus aureus. In the cases in which phage therapy was administered, antibiotic resistance accounted for 50% of cases, with multidrug-resistant bacteria being the most common reason (38%) for the phage request.

In 53 cases, potential phages matches were found, but only 20 treatments in 18 patients were administered; in the remaining 33 cases, phage therapy was not pursued for various reasons. Of the 18 patients who received intravenous phage therapy, 14 (78%) achieved clinical remission, and 4 (22%) were classified as treatment failure. No major side effects were reported.

"The use of phages with additional therapy resulted in high response rate," the study authors wrote. "The observed success also resulted in a substantial increase of phage therapy requests that is challenging due to reduced human grade phage availability and lack of proper authorized indications."

The authors say that while the sample size is small, they hope that sharing this information, along with conducting clinical trials, will help better define future indications for phage therapy and improve outcomes.