Targeting older adults with underlying health conditions—as opposed to the general population—for respiratory syncytial virus (RSV) vaccines would reduce spending and prevent illness, according to a modeling study yesterday in the Canadian Medical Association Journal (CMAJ).

The study compared the cost-effectiveness of different vaccine programs in different age groups with different medical risks. 

The model considered a population of 100,000 people aged 50 years and older. Vaccine characteristics were based on RSV vaccines authorized in Canada as of May 2024, with vaccine protection assumed to last 2 years. 

The cost-effectiveness threshold was $50,000 per quality-adjusted life year (QALY).

Optimal in oldest adults with underlying conditions

According to the study authors, without vaccination, they projected 131,389 (95% credible interval [CrI], 120,070 to 143,581) medically attended RSV cases, 12,068 (95% CrI, 10,324 to 13,883) hospital admissions, and 1,015 (95% CrI, 617 to 1,450) deaths annually among Canadians aged 60 years and older.

Vaccinating strategies based on age plus risk for RSV-related complications were projected to avert a median of 20% to 31% of outpatient cases, 38% to 42% of hospital cases, and 39% to 42% of deaths, the authors said.  Vaccines were most cost-effective, according to the model, when given to adults ages 70 and older, with one or more chronic medical condition.

We found that vaccination of older adults may be less costly and more effective than no vaccination.

"We found that vaccination of older adults may be less costly and more effective than no vaccination and that vaccinating people aged 70 years and older with chronic medical conditions is likely to be cost-effective based on commonly used cost-effectiveness thresholds," said Ashleigh Tuite, PhD from the Public Health Agency of Canada in a CMAJ press release.

"Strategies focused on adults with underlying medical conditions that place them at increased risk of RSV disease are more likely to be cost-effective than general age-based strategies," Tuite added. 

A study of 1.8 million adults published in JAMA Network Open suggests that—except for a slightly higher risk of inflammatory bowel disease and blistering skin disorders in a subgroup hospitalized for SARS-CoV-2 Omicron variant infection—Delta or Omicron BA.1 or BA.2 infection in highly vaccinated adults doesn't significantly raise the long-term risk of autoimmune diseases.

Led by investigators from the National Centre for Infectious Diseases in Singapore, the study team used the SARS-CoV-2 registry and a healthcare claims database to compare the long-term risk of new autoimmune diseases after Delta or Omicron BA.1 or BA.2 infection in recipients of COVID-19 vaccines and boosters with that in uninfected controls. The study period was September 2021 to March 2022, with a 300-day follow-up.

Of all participants, 27.2% had COVID-19, 72.8% were controls, 51.9% were women, and the average age was 49 years.

"Studies have reported increased risk of autoimmune sequelae after SARS-CoV-2 infection," the researchers wrote. "However, risk may potentially be attenuated by milder Omicron (B.1.1.529) variant infection and availability of booster vaccination."

Boosters may lower risk of new autoimmune disease

During Delta predominance, 104,179 participants had COVID-19 infections and 666,575 were controls, while 375,903 and 619,379 controls, respectively were infected during Omicron predominance. A total of 81.1% of infected participants had completed the primary two-dose COVID-19 mRNA vaccine series amid the Delta era, and 74.6% received boosters during the Omicron period.

Continued surveillance for autoimmune conditions arising after COVID-19 is still necessary during the Omicron variant era.

A significantly higher risk of 12 studied autoimmune diseases wasn't observed during the Delta or Omicron periods, except for inflammatory bowel disease (adjusted hazard ratio [aHR], 2.23) and bullous (blistering) skin disorders (aHR, 4.88) in hospitalized COVID-19 patients amid Omicron. An elevated risk of vasculitis was documented in vaccinated Omicron patients (aHR, 5.74) but not those who received boosters.

The study authors concluded, "Continued surveillance for autoimmune conditions arising after COVID-19 is still necessary during the Omicron variant era."

• The North Carolina Department of Health and Human Services yesterday reported the state’s first measles case since 2018. In a statement, health officials said the patient is a child in Mecklenburg County who was probably exposed during international travel. The parents kept the child home after returning to the state, except for one medical visit during which health providers took appropriate precautions. Cases in the United States are up sharply this year, part of a global rise in cases.
• The US Centers for Disease Control and Prevention (CDC) last week in an update that it projects that vaccine manufacturers will supply the US market with 148 million flu vaccine doses for the 2024-2025 season, with trivalent (three-strain) vaccine making up all formulations. Vaccine makers aren’t reporting any manufacturing delays, the CDC said. Nearly all (94%) of the supply will be thimerosal-free, and about 80% will be made using egg-based manufacturing technology. For comparison, the CDC had projected as many as 156.2 million to 170 million for the 2023-2024 season. It emphasized that projections may change as the season progresses.
• A polio vaccination campaign under way in Gaza has now moved to the northern part of the country, with activities slated to last until September 12, World Health Organization (WHO) Director-General Tedros Adhanom Ghebreyesus, PhD, said today on X. He called on groups in the region to maintain a humanitarian pause and respect the safety of healthcare workers. Following the recent detection of circulating vaccine-derived poliovirus type 2 in a child from Gaza, along with environmental positives, health groups planned and launched a two-round vaccine campaign earlier this month targeting 640,000 children.