The US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) today confirmed 11 more H5N1 avian flu outbreaks in dairy cattle, all in California. The new confirmations push the state's total to 504 and the national total to 718 in 15 states.

California is the country's largest dairy producer, with roughly 1,300 commercial herds. The outbreaks began in late August and have now affected almost 40% of the state's dairy herds.

Poultry outbreaks

Also, APHIS confirmed more avian flu outbreaks in poultry in three states. In California—hit hard by outbreaks in both cattle and poultry—the virus struck a commercial turkey farm housing more than 61,000 birds in Sacramento County. New outbreaks were also confirmed at two commercial farms in Stanislaus County: a turkey producer and a layer facility. 

Outbreaks were also reported in backyard poultry flocks in California's Riverside County, Kansas's Douglas County, and Utah's Utah County. 

Researchers report that immunity against pertussis (whooping cough) was sustained 5 years after receipt of a recombinant vaccine in adolescents and young adults, a finding that they said supports its use as a booster in adolescents.

The study was a follow-up of participants vaccinated 5 years earlier, at ages 12 to 17 years, with recombinant acellular pertussis vaccine during a phase 2/3 randomized clinical trial conducted from July 2015 to November 2016 in Thailand. Participants had received three doses of whole-cell pertussis vaccine as infants.

Of 159 participants, 55 received the pertussis-only vaccine formulation (aP_gen), 52 received tetanus-diphtheria-pertussis (TdaP_gen), and 52 received the Tdap_chem booster.

The team collected a blood sample and measured serum PT-immunoglobulin G (IgG) and filamentous hemagglutinin (FHA)-IgG antibody levels in all participants and pertussis toxin (PT) neutralizing antibody titers in the 55 aP_gen recipients. Antibody concentrations were analyzed with enzyme-linked immunosorbent assay (ELISA) and Chinese hamster ovary assays.

"Pertussis toxin (PT), particularly if genetically detoxified (PT_gen), represents the main antigen ensuring protection from pertussis disease," the authors wrote. "We previously demonstrated that recombinant acellular pertussis vaccines containing PT_gen are more immunogenic and induce significantly higher PT-neutralizing antibody titers in adolescents than chemically inactivated tetanus-diphtheria-pertussis booster vaccines (Tdap_chem)."

The results were published today in JAMA Network Open.

Results support use as boosters in teens, adults

Five years post-vaccination, levels of neutralizing anti-PT antibodies were more than fourfold greater than the seropositivity cutoff of 5 international units per milliliter (IU/mL). PT neutralizing antibody concentrations were 2.5-fold (aP_gen) and threefold (TdaP_gen) higher than prevaccination. PT-IgG antibody levels were greater than 20 IU/mL in 75% of aP_gen vaccine recipients and 56% of TdaP_gen recipients, compared with 27% of Tdap_chem recipients.

"Long-lasting protection was demonstrated earlier in an efficacy trial for PT_gen-containing [genetically detoxified] recombinant vaccines after primary immunization in infants," the authors wrote. "Our findings suggest that PT_gen-containing vaccines can also offer longer-lasting protection in adolescents, supporting their use as booster vaccines in adolescents and adults to enhance population immunity.

The World Health Organization (WHO) announced today that it has granted prequalification to a rapid molecular diagnostic test for tuberculosis (TB).

The test, Xpert MTB/RIF Ultra, is a nucleic acid amplification test that detects the genetic material of Mycobacterium tuberculosis in sputum samples and provides results within hours. It also identifies mutations associated with rifampicin resistance, which is a key indicator of multidrug-resistant TB. 

WHO prequalification involves product testing, performance evaluation, inspection of manufacturing sites, and other activities aimed at ensuring countries have access to key health products that meet global standards of quality, safety, and efficacy. The WHO's assessment for prequalification of Xpert MTB/RIF Ultra was based on information submitted by the manufacturer, Cepheid Inc., and reviewed by Singapore's Health Sciences Authority.

A 'critical milestone'

The test is the first test for TB diagnosis to meet the WHO's prequalification standards. WHO officials say accurate and early detection of TB, particularly drug-resistant strains, is a global health priority.

"This first prequalification of a diagnostic test for tuberculosis marks a critical milestone in WHO's efforts to support countries in scaling up and accelerating access to high-quality TB assays that meet both WHO recommendations and its stringent quality, safety and performance standards," Yukiko Nakatani, MD, PhD, WHO Assistant Director-General for Access to Medicines and Health Products, said in a press release. "It underscores the importance of such groundbreaking diagnostic tools in addressing one of the world's deadliest infectious diseases."

The WHO's most recent annual report on TB shows 8.2 million people were diagnosed with TB in 2023—the highest number of cases recorded by the agency since it began global TB monitoring in 1995. An estimated 400,000 of those cases were multidrug-resistant.

A population-based study in Ontario found a higher prevalence and risk of concomitant bacterial infection in patients infected with influenza and respiratory syncytial virus (RSV) compared with SARS-CoV-2, researchers reported this week in Open Forum Infectious Diseases. 

But the risk of bacterial infections in COVID-19 patients was substantially elevated after 48 hours compared with the other viruses.

Using datasets from Ontario Laboratories Information System, a team led by researchers from the Institute for Clinical Evaluative Sciences in Toronto investigated the prevalence of concomitant bacterial infections in patients with lab-confirmed influenza A and B (FLUA and FLUB) and RSV from 2017 through 2019 and SARS-CoV-2 from 2020 through 2021. They also examined whether risk factors, such as patient characteristics, are associated with differential risks of concomitant bacterial infection. Concomitant infections were classified into coinfection (–2 to +2 days from viral infection) and secondary infection (more than 2 days after viral infection).

Among the 885,004 respiratory viral infections observed during the study period, 4,230 (0.5%) were associated with concomitant bacterial infections, which were found in 422 of 8,891 (4.7%) FLUB patients, 861 of 22,313 (3.9%) FLUA patients, 428 of 12,744 (3.4%) RSV patients, and 2,519 of 841,026 (0.3%) COVID-19 patients. The most prevalent species causing concomitant bacterial infection were Staphylococcus aureus,Streptococcus pyogenes, and Pseudomonas aeruginosa.

Higher risk of secondary infection with SARS-CoV-2

After adjusting for covariates, the odds ratio for bacterial infection was 1.69 (95% Confidence Interval (CI), 1.48 to 1.93) for FLUA, 2.30 (95%CI, 1.97 to 2.69) for FLUB, and 1.56 (95%CI, 1.33 to 1.82) for RSV compared with SARS-CoV-2. Stratified analysis revealed that while the adjusted odds of bacterial co-infection were lower for SARS-CoV-2, odds of secondary bacterial infection with SARS-CoV-2 were higher than FLUA, FLUB, and RSV.

The study authors say the findings have important implications for antimicrobial stewardship.

"Antimicrobial prescribing is common in patients with COVID-19 which can adversely impact antimicrobial resistance," they wrote. "However, early empiric prescribing in non-critically ill patients is not justified given the relatively low risk of co-infection. Such findings should be considered to support judicious prescribing decisions in patients with suspected or proven COVID-19."