New research was presented at IDWeek 2022, the joint annual meeting of the Infectious Diseases Society of America, the Society for Healthcare Epidemiology of America, the HIV Medicine Association, the Pediatric Infectious Diseases Society, and the Society of Infectious Diseases Pharmacists, from October 19-23. The features below highlight some of the studies presented during the conference.

Vaccination Program Provides ‘Remarkable’ Decrease in Varicella

In 1995, the United States became the first country to initiate a universal childhood vaccination program against varicella. Jessica W. Leung, MPH, and colleagues examined the impact of the program on national disease incidence over 25 years, from the pre-vaccine period (1990-1994) through 2019. Within the 10 years of the one-dose program, varicella incidence, hospitalization, and mortality rates decreased from 71% to 90%. The ongoing, limited transmission of varicella led to a shift to a 2-dose policy, and by 2019, reductions were greater than 97% for incidence, 94% for hospitalizations, and 97% for deaths. The highest decrease was seen among persons born during the varicella vaccination program, with a 99% reduction in incidence, a 97% reduction in hospitalizations, and a 99%
reduction in deaths. The 2-dose program further decreased the number, size, and duration of outbreaks, and, over the entire program, the proportion of outbreaks with less than 10 cases increased from 28% to 73%. “For chickenpox to go from being an inevitability of childhood to being rarely seen in just one generation is truly remarkable,” a coauthor said in a statement.

Diagnostic Stewardship Reduces Unnecessary Antibiotics for Asymptomatic Bacteriuria

National guidelines recommend against the use of antibiotics for asymptomatic bacteriuria (ASB), but as many as 80% of hospitalized patients with ASB receive them. Valerie Vaughn, MD, MSc, and colleagues conducted a 4-year study across 46 hospitals that implemented pay-for-performance metrics related to unnecessary treatment of ASB.
During the study, the percentage of patients who received antibiotics for UTIs who also had ASB decreased from 29.0% to 16.9%. Diagnostic stewardship, which ensured that patients received the correct tests at the appropriate time, was responsible for nearly all the improvement seen, according to the study results; specifically, the percent of urine cultures positive for ASB significantly decreased. “Most efforts to combat antimicrobial resistance have focused on prescribing, but our research indicates that more progress can be made by looking further upstream—before a prescription is ever written,” Dr. Vaughn said in a statement. “Diagnostic stewardship is an important and effective
part of overall responsible antibiotic use in health care settings.”

Engagement in Care ‘Paramount’ to Increase Life Expectancy in HIV

Structural barriers that influence inequities in HIV care prompted Katherine M. Rich, MPH, and colleagues to examine the impact of these disparities on life expectancy among men who have sex with men (MSM) in the US. Life expectancy from age 15 was projected in five scenarios: 1) status quo HIV care; 2) earlier diagnosis (via annual testing); 3) improved retention in care; 4) improved viral suppression; and 5) a combined strategy of earlier diagnosis, better retention in care, and improved viral suppression. For MSM receiving status quo care, projected life expectancy from age 15 was 52.2 for Black MSM and 58.5 for White MSM. With annual testing, BMSM would gain 0.6 life years and WMSM would gain 0.3 life-years versus status quo care. Improving retention in care to 95%
would result in a gain of 1.4 life-years for Black MSM and 1.0 life-years for White MSM; Black MSM would gain 1.1 life-years if viral suppression improved to 95% among those in care, while White MSM would gain 0.3 life-years. With the combined strategy, Black MSM would gain 3.4 life-years (life expectancy from age 15: 55.6) and White MSM would gain 1.6 life-years (life expectancy from age 15: 60.1). “Our analysis emphasizes that maintaining engagement in care is paramount to improving life expectancy and clinical outcomes among people living with HIV,” Rich said in a statement.

Physical Fitness Declines After COVID-19 Among Active Duty US Military Members 

The potentially detrimental impact of COVID-19 on the physical fitness of active-duty US military members prompted Stephanie A. Richard, PhD, MHS, and colleagues to examine the long-term functional impact of COVID-19 in this patient population, as well as other military healthcare beneficiaries. Individuals completed surveys on difficulties with daily activities, exercise, and physical fitness performance at enrollment and 1, 3, 6, 9, and 12 months. Among 5,910 participants, 55% tested positive for SARSCoV-2 at least once during the study. More than a
quarter of patients who tested positive for SARSCoV-2 (34.3%) described new or increased difficulty exercising compared with 14.8% of individuals who tested negative for SARS-CoV-2 (P<0.01). The most frequently symptoms were dyspnea and fatigue. Among active-duty members, 43.2% of participants positive for SARSCoV-2 noted that their physical fitness scores had worsened during the study period compared with 24.3% of participants negative for SARS-CoV-2. For individuals who test positive for SARS-CoV-2, difficulty exercising and performing daily activities
was highest within 1 month of the first positive test; this only improved slightly at 12 months. “These results underscore the value of vaccination, not just for preventing death and disease but for preserving long-term [QOL],” a coauthor said in a statement.

COVID-19 Omicron BA.1 Variant Booster Improves Antibody Response With No New Safety Concerns 

A phase 2/3 clinical trial that examined the safety and immunogenicity of the bivalent mRNA COVID-19 booster vaccine that targets the omicron BA.1 variant found that the booster provided a significantly increased antibody response compared with the original vaccine and no new safety signals. Spyros Chalkias, MD, and colleagues
examined safety, reactogenicity, and immunogenicity 28 days after the booster dose in participants with no prior SARS-CoV-2 infection who received either mRNA-1273.214 (N=334) or mRNA1273 (N=260). Neutralizing antibody geometric mean titers (GMTs) against omicron BA.1 were 2,372.4 (95% CI, 2,070.6-2,718.2) in the mRNA1273.214 group and 1,473.5 (95% CI, 1,271,708.4) in the mRNA-1273 group. The model-based GMT ratio (GMR) of mRNA-1273.214 compared with mRNA-1273 was 1.75, meeting pre-specified superiority criterion against omicron BA.1. Pre-specified criterion for non-inferiority against the ancestral SARS-CoV-2 strain was also met. Additionally, mRNA-1273.214 provoked higher GMTs (727.4) than mRNA-1273 (492.1) against omicron subvariants BA.4/BA.5 (GMR, 1.69; 95% CI, 1.51-1.90). Binding antibody responses against alpha, beta, gamma, delta, and
omicron were numerically higher in the mRNA1273.214 group compared with mRNA-1273, and mRNA-1273.214 GMTs were consistently higher across age (18 to <65 and ≥65) and pre-booster SARS-CoV-2 infection subgroups. Safety and reactogenicity were similar for both groups.