News Scan for Feb 14, 2022

News brief

Mix-n-match COVID-19 vaccine boosters may result in fewer infections

People who received a different brand of COVID-19 vaccine booster than they did in the primary series had lower rates of infection than those who received the same brand, according to a study in Singapore published late last week in JAMA.

The study also found that participants who received a booster of any vaccine brand after the primary Pfizer/BioNTech series had lower rates of severe COVID-19 than did their unboosted peers. In a similar study earlier last week, US scientists writing in the New England Journal of Medicine found better booster protection only among those who initially received the Johnson & Johnson COVID vaccine.

The Singapore team analyzed rates and severity of COVID-19 infections among participants 60 years and older from Sep 15 to Oct 31, 2021, amid a surge of cases that the authors said was related to the relaxation of public health measures. In response to the surge, that age-group was invited to receive a Pfizer or Moderna vaccine booster.

Of 703,209 eligible people, 576,132 received boosters; 59% of them were 60 to 69 years old, 29% were 70 to 79, 11% were 80 and older, with 53% were women.

The incidence of COVID-19 infection and severe disease among participants who received Pfizer for both their primary series and booster (homologous vaccination) were 227.9 and 1.4 per million person-days. In contrast, the incidence of infection and severe disease among those receiving a different booster (heterologous) were 147.9 and 2.3 cases per million person-days, respectively, with incidence rate ratios (IRRs) of 0.18 (95% confidence interval [CI], 0.14 to 0.23) and 0.08 (95% CI, 0.01 to 0.56).

For recipients of a homologous Pfizer series, the incidence of infection and severe COVID-19 were 0.27 (95% confidence interval [CI], 0.26 to 0.29) and 0.05 (95% CI, 0.03 to 0.08), respectively. Among recipients of three Moderna doses, the incidence of infection was 133.9 cases per million person-years (IRR, 0.20; 95% CI, 0.14 to 0.27).

Rates of infection and severe illness among participants who received two doses of Pfizer vaccine but no booster were 600.4 and 20.5 per million person-days, respectively.

The authors write that the data "suggest that heterologous boosting may provide greater protection against COVID-19."
Feb 11 JAMA research letter


UK confirms third imported Lassa case, which proved fatal

British health officials late last week confirmed a third Lassa fever case in a patient with a suspected infection who has died, bringing the confirmed number in a family cluster to three.

In a statement, the UK's Health Security Agency (HSA) said it is contacting people who had contact with the family members before they were diagnosed for assessment, support, and advice. It also said the risk to the public remains low.

The two earlier cases and the probable case were announced last week and involved members of the same family in eastern England who had recently traveled to West Africa, where the viral hemorrhagic disease is endemic. One patient has recovered and another is being treated at Royal Free London hospital.

Lassa virus spreads by household items or food contaminated with urine or feces of infected rats. It can also spread among humans through infected body fluids. Imported cases occur sporadically outside of West Africa, with the United Kingdom reporting its last cases in 2009 and the United States reporting its last case in 2015.
Feb 11 UK HSA statement
Feb 9 CIDRAP News scan


H5N1 avian flu hits more poultry in Africa and Europe

Three countries—Cameroon, Denmark, and Romania—reported new highly pathogenic H5N1 avian flu outbreaks in poultry, according to the latest notifications from the World Organisation for Animal Health (OIE).

Cameroon's outbreak, its first since 2017, began on Jan 29 at a layer farm in the country's West region, killing 11,984 of 13,513 susceptible birds. Officials said the layer birds were kept in buildings that have an automatic watering system. So far, the source of the virus isn't known.

In Europe, Denmark reported another H5N1 event that started on Feb 10 at a layer farm in Zealand region, killing 400 of 800 birds. The rest were culled to contain the spread of the virus. And Romania'sn outbreak began on Feb 10 in backyard poultry in Ialomita County in the southeast, killing 49 of 65 birds.
Feb 13 OIE report on H5N1 in Cameroon
Feb 11 OIE report on H5N1 in Denmark
Feb 14 OIE report on H5N1 in Romania

Stewardship / Resistance Scan for Feb 14, 2022

News brief

US surveillance study finds high incidence of ESBL-E infections

An active laboratory- and population-based surveillance study conducted at five US sites found a high incidence of infections caused by extended-spectrum beta-lactamase–producing Enterobacterales (ESBL-E), researchers reported today in Infection Control & Hospital Epidemiology.

The pilot study, led by researchers with the Centers for Disease Control and Prevention (CDC), identified incident ESBL-E cases at five Emerging Infections Program (EIP) sites in New York, Georgia, Tennessee, Colorado, and New Mexico over a 3-month period (October to December 2017).

An incident ESBL-E case was defined as an Escherichia coli, Klebsiella pneumoniae, or Klebsiella oxytoca isolate resistant to at least one extended-spectrum cephalosporin and non-resistant to carbapenems. Antimicrobial susceptibility testing and whole-genome sequencing was conducted on a convenience sample of case isolates.

The researchers identified 884 ESBL-E incident cases among 815 patients. Of the 884 cases, 790 (89%) were E coli bacteremia, and 94 (11%) were K pneumoniae bacteremia. The estimated annual incidence in the three sites conducting population-based surveillance (New York, New Mexico, and Tennessee) was 199.7 per 100,000 population. Among the cases, 393 (47%) were classified epidemiologically as community-associated, 282 (34%) as healthcare-associated community-onset, and 40 (5%) as hospital-onset.

Among 136 isolates (15%) tested at the CDC, 122 (90%) met the surveillance definition phenotype; 114 (93%) of 122 were shown to be ESBL producers by clavulanate testing. In total, 111 (97%) of confirmed ESBL producers harbored a bla CTX-M gene. Among ESBL-producing E coli isolates, 52 (54%) were sequence type ST131; 44% of these cases were community-associated.

The study authors say the findings are concerning not only because the incidence of ESBL-E infections in the United States appears to be much higher than previously established estimates for other resistant phenotypes, such as carbapenem-resistant Enterobacterales (2.93 infections per 100,000) but also because only 30% occurred in hospitalized patients. The CDC has previously highlighted ESBL-E as a serious antibiotic resistance threat.

"In conclusion, ESBL-E causes a high burden of infections in the community and in healthcare, and additional data are needed to further characterize risk factors and sources of acquisition to focus prevention efforts," they write.

The EIP has implemented ongoing ESBL-E surveillance at six US sites based on the findings.
Feb 14 Infect Control Hosp Epidemiol abstract


VA study highlights inappropriate asymptomatic bacteriuria treatment

An in-depth review of provider documentation at eight Veterans Affairs (VA) sites found that more than a quarter of asymptomatic bacteriuria (ASB) cases were inappropriately treated with antibiotics, researchers reported last week in the American Journal of Infection Control.

In the case-control study, a team led by researchers from Baylor College of Medicine reviewed a random sample of 10 positive urine cultures per month, per facility, classifying them as urinary tract infection or ASB and as treated or untreated. They then reviewed provider-documented text from medical charts that was associated with urine culture ordering to identify symptoms and factors associated with inappropriate ASB treatment.

Out of 960 cultures analyzed from October 2018 through September 2018, 575 were ASB cases. Of these, 158 (27.5%) were inappropriately treated with antibiotics. After controlling for known predictors of ASB treatment, the researchers found that abdominal pain, confusion, decreased urine output, falls, urine characteristics, abnormal vital signs, laboratory values, and voiding issues were all significantly associated with inappropriate ASB treatment. Misleading symptoms with the strongest effect included falls (odds ratio [OR], 3.19), abnormal vital signs (OR, 3.18), and abdominal pain (OR, 2.44).

ASB-treated patients received an average of 1.4 antibiotics, with cephalosporins (41%) and fluoroquinolones (21%) being the most common classes prescribed.

The study authors say the findings suggest a role for diagnostic stewardship to accompany antibiotic stewardship and that future research should examine the factors associated with inappropriate ASB treatment.

"Teasing out these unique cues can help improve our understanding behind improper ASB treatment and should be incorporated into teaching vignettes used in antibiotic stewardship interventions," they wrote.
Feb 11 Am J Infect Control abstract

This week's top reads