Third COVID vaccine dose boosts effectiveness against hospitalization

A third COVID-19 vaccine dose increased vaccine effectiveness (VE) against hospitalization from 82% to 97% among adults with healthy immune systems and from 69% to 88% among those with impaired immunity, according to a study today in Morbidity and Mortality Weekly Report (MMWR).

Led by researchers from the Centers for Disease Control and Prevention (CDC) COVID-19 Emergency Response Team, the study involved 1,385 COVID-19 patients and 1,567 uninfected controls admitted to 21 US hospitals from Aug 19 to Dec 15, 2021. The study period encompassed the emergence and eventual dominance of the highly transmissible Delta (B1617.2) variant.

The researchers estimated the VE of a third dose of the Pfizer/BioNTech and Moderna mRNA vaccines against COVID-related hospitalization in 312 adults who received a third shot at least 7 days before symptom onset, relative to 1,251 adults who hadn't received a third dose. They estimated VE using logistic regression, comparing the chances of being vaccinated versus unvaccinated among COVID-19 patients and controls. Median patient age was 62 years, 49% were women, and 58% were White.

Of 1,875 participants with uncompromised immune systems, 57% were unvaccinated against COVID-19, 36% had received two doses of vaccine, and 7% had been given a third dose. VE against COVID-19–related hospitalization in this group was 97% among participants given a third dose (95% confidence interval [CI], 95% to 99%), compared with 82% (95% CI, 77% to 86%) among two-dose recipients.

Of 1,077 adults with immune-compromising conditions, 30% were unvaccinated, 53% had received two doses, and 17% had received a third dose. VE was 88% (95% CI, 81% to 93%) among third-dose recipients, versus 69% (95% CI, 57% to 78%) among those who had received two doses.

The study authors noted that the study was conducted before the emergence and eventual dominance of the Omicron (B.1.1.529) variant. COVID-19 VE, they said, may now be lower than for other variants because Omicron may be able to evade immune protection, but early data show some promise.

"Early evidence suggests that a third mRNA vaccine dose elicits markedly stronger neutralizing antibody responses to the Omicron variant compared with responses to 2 vaccine doses, and increases VE against severe disease following infection with the Omicron variant," they wrote.

In October, the CDC began recommending a three-dose primary regimen plus a fourth dose as a booster for those with impaired immune systems.
Jan 28 MMWR study

Studies show Omicron variant less severe but causes more reinfections

Two studies published yesterday in Eurosurveillance show the Omicron variant leads to fewer hospitalizations than the Delta variant, but an increased risk of infection in vaccinated and previously infected people.

The hospitalization study was based on medical records in Norway. Overall, 39,524 Omicron (43%) and 51,481 Delta cases (57%) were included in the study, with positive tests collected from Dec 6, 2021 to Jan 9, 2022.

The authors found Omicron carried an overall 73% reduced risk of hospitalization (aHR = 0.27; 95% confidence interval [CI], 0.20 to 0.36) compared with Delta.

The authors said this finding confirms data from South Africa, the United Kingdom, Canada, and the United States, which have thus shown Omicron is associated within 36% to 66% reduced risk of hospitalization compared with Delta.

In a second study from the Netherlands, the authors used confirmed COVID-19 cases collected from Nov 22, 2021, to Jan 19, 2022, to show Omicron carried an increased risk of infection compared with Delta in people with COVID-19 immunity—either from previous infections or vaccination.

Based on 174,349 cases, 66.1% of patients who had Omicron had received a primary vaccination (two dose) series, compared with 61.5% of Delta patients. Also, 6.5% infected with Omicron had a previous infection, compared with 1.4% of Delta.

"We showed that individuals with a previous infection had a higher risk of infection with Omicron than with Delta compared with naïve individuals, suggesting that previous infection with another SARS-CoV-2 variant provides lower levels of protection against Omicron than against Delta infection," the authors wrote.
Jan 27 Eurosurveill Norway study
Jan 27 Eurosurveill Dutch study

Our weekly wrap-up of antimicrobial stewardship & antimicrobial resistance scans

New EU rules on antibiotic use on farms take effect

New rules limiting the use of antibiotics in food-producing animals in the European Union went into effect today.

The revamped legislation on veterinary medicinal products, adopted 3 years ago by the European Commission, bans the use of antibiotics—including those used in medicated feed—to prevent disease in groups of animals, and restricts the use of antibiotics to control the spread of disease. It also reinforces a ban on the use of antibiotics for growth promotion, obligates member states to collect data on sales and use of antibiotics in food-producing animals, and provides incentives to stimulate development of new veterinary medicines.

EU officials say the legislation will support reaching the goals of the European One Health Action Plan and the Farm to Fork Strategy against antimicrobial resistance (AMR), which aims to reduce sales of antibiotics for farmed animals in the EU by 50% by 2030.

"The new rules will ensure that, as of today, treatments by antimicrobials for animals will be administered when, and only when, there is a real need for them," Stella Kyriakides, EU Commissioner for Health and Food Safety, said in a press release. "Together with the new legislation on medicated feed, which will ban the preventive use and restrict prescriptions of antimicrobial in medicated feed, the new rules will significantly strengthen the fights against AMR."  

In a related document released today, the European Public Health Alliance (EPHA) said that, while it welcomed the new regulations, it's concerned about the probability for widespread noncompliance because there's little indication Europe is moving away from the type of intensive farming systems that rely on the routine use of antibiotics.

To ensure that the new EU regulations are implemented in full, EPHA put forth 10 recommendations that it believes could help achieve significant cuts in livestock antibiotic use. These include limiting the use of antibiotics in livestock to individual treatments, collecting data on antibiotic use by species and farming system to identify factors linked to high antibiotic use, restricting use of highest-priority critically important antibiotics in livestock, improving hygiene on farms, and providing animals with access to the outdoors. 
Jan 28 European Commission press release
Jan 28 EPHA report

New coalition to focus on antibiotic overuse in agriculture

Originally published by CIDRAP News Jan 27

US PIRG (Public Interest Research Group) Education Fund today announced the launch of a new coalition dedicated to reducing antibiotic use in agriculture.

The Coalition to Preserve Antibiotics includes physicians, farmers, and animal and public health professionals. The group says in it mission statement that while overuse of antibiotics in any setting can promote the development of antibiotic-resistant bacteria, its focus is on reducing antibiotic use in agriculture because roughly two thirds of the medically important antibiotics sold in the United States are for use in food-producing animals.

Coalition members believe that antibiotics can and should be used to treat sick animals, but they say the way the conventional food system raises animals for food often relies too heavily on the routine use of antibiotics to compensate for conditions that can lead to disease, and that this overuse breeds antibiotic-resistant pathogens that can threaten both animal and human health.

"Antibiotic resistant organisms are a dire public threat in our hospitals, food supply, communities and environment," infectious disease physician and coalition member Sameer Patel, MD, MPH, said in a press release. "Healthcare workers, farmers, restaurateurs, consumers—all of us can make changes now to reduce unnecessary antibiotic use and decrease the threat of antimicrobial resistance." 

The coalition says it will work with stakeholders at all levels of government, industry, and academia to advance better antibiotic stewardship in agriculture.
Jan 27 US PIRG Education Fund press release

Study suggests shorter IV antibiotic durations for young infants with UTIs

Originally published by CIDRAP News Jan 25

A review and meta-analysis of studies on urinary tract infections (UTIs) in young infants suggests shorter intravenous (IV) antibiotic courses, with an early switch to oral antibiotics, should be considered, Australian researchers reported yesterday in Pediatrics.

While international guidelines recommend admitting all infants 90 days or younger with a UTI to the hospital for initial IV antibiotic therapy, there is no consensus on the optimal time for when young infants can be safely switched from IV to oral therapy, and considerable variation in IV antibiotic duration for UTIs in this age-group remains. To determine if a shorter IV course may be appropriate for young infants with UTIs, researchers screened 10,181 records and identified 18 studies involving 16,615 young infants that met the inclusion criteria.

The largest two studies on bacteremic UTI found no difference in the rates of 30-day recurrence or 30-day all-cause hospitalization between young infants who received 7 days or less of IV antibiotics and those who received more than 7 days.

For infants with non-bacteremic UTIs, there was no significant difference in the 30-day adjusted recurrence rate between those treated with 3 days or less of IV antibiotics and those treated with more than 3 days. Three studies used oral antibiotics alone and reported good outcomes, although only 85 infants in those studies were 90 days or younger.

"These findings have important implications for clinical practice, because shorter IV antibiotic courses with an early switch to oral therapy can improve the quality of life of children and their families, reduce the length of hospital stay, the risk of nosocomial infections, and health care costs," the review authors wrote.

The authors note that the recommendations are only for young infants when meningitis has been excluded and who have no features of sepsis.
Jan 24 Pediatrics abstract

Study highlights non-guideline adherent antibiotic treatment for C diff

Originally published by CIDRAP News Jan24

A review of Clostridioides difficile infection (CDI) treatments at 10 community hospitals found that only 50% of treatment regimens were adherent to guidelines regarding use of fidaxomicin, researchers reported today in Infection Control & Hospital Epidemiology.

The review looked at all adult non-hospice patients with confirmed CDI who received fidaxomicin at 10 community hospitals within the University of Pittsburgh Medical Center (UPMC) system from May 2018 through August 2019. Based on updated CDI treatment guidelines from Infectious Diseases Society of America and the Society for Healthcare Epidemiology of America, UPMC in April 2018 broadened fidaxomicin use but did not recommend it for initial treatment of CDI.

The aim of the study was to better understand fidaxomicin use following introduction of the updated UPMC guidelines, which were communicated to pharmacy directors and local antimicrobial stewardship programs at all UPMC hospitals.

Average fidaxomicin use remained low but increased by 30% pre-updated guidelines to post-updated guidelines. Of the 104 fidaxomicin regimens prescribed, 52 were non-adherent to UPMC guidelines. The main reasons for non-adherence included use for fulminant CDI (36 prescriptions) and concurrent use with other CDI treatment (29), neither of which were recommended at the time by the UPMC guidelines. Infectious disease (ID) physicians accounted for 25 (48%) of the 52 non-adherent regimens.

The study authors say the findings highlight the importance of including ID consultants in antimicrobial stewardship programs.

"Although release of new or updated clinical guidelines provides opportunities to advance patient care, dissemination of this information is often slow," they write. "Antimicrobial stewardship programs play a critical role in dissemination and should ensure that all providers, including ID staff, exercise appropriate stewardship in their prescribing practices."
Jan 24 Infect Control Hosp Epidemiol abstract

Urgent care study finds decline in antibiotic prescribing during COVID-19

Originally published by CIDRAP News Jan 24

An analysis of antibiotic prescribing at two academic urgent care clinics found a sustained decline in antibiotic prescribing during the COVID-19 pandemic, despite a transition to telemedicine, researchers reported late last week in Open Forum Infectious Diseases.

In the study, researchers from Stanford University School of Medicine compared the proportion of clinic and telemedicine visits at two academic urgent care clinics during which antibiotics were prescribed before (December to January 2019) and during (January to December 2020) the pandemic. They extracted diagnoses and antibiotic data from the electronic medical record and assigned each encounter a disease category and an antibiotic prescribing tier based on whether antibiotics were almost always (tier 1), sometimes (tier 2), or almost never (tier 3) indicated.

A total of 69,842 encounters were analyzed, with 33,591 occurring before and 36,251 during COVID-19. Telemedicine visits rapidly increased in March 2020 and became the dominant visit modality thereafter. The pre-COVID-19 antibiotic prescribing rate was 17%, compared with 11% during COVID-19. The antibiotic prescribing rate was 9% in telemedicine and 15% in clinic visits during COVID-19. The overall decline in antibiotic prescribing was driven primarily by encounters for a respiratory diagnosis and was not observed in encounters for gastrointestinal, genitourinary, skin, or other infections.

Among respiratory encounters, antibiotics were prescribed less frequently across all tiers during COVID-19: tier 1 (63% vs 56%), tier 2 (37% vs 27%), and tier 3 (16% vs 5%). Less than 1% of COVID-19 encounters were associated with an antibiotic prescription.

The study authors say the reasons for the decline likely include changes in healthcare use, local epidemiology, and the impact of local masking and physical distancing measures on common respiratory pathogen transmission.

"Future studies are needed to investigate these factors with a goal of promoting optimal antibiotic prescribing for all viral respiratory conditions," they wrote. "The big question remains as to whether the lower antibiotic prescribing rates will be sustained beyond the COVID-19 pandemic."
Jan 22 Open Forum Infect Dis abstract