Pneumococcal vaccination uptake remains low among high-risk adults in Canada, including those aged 65 years or older and patients with chronic conditions, according to a new report.

Nearly half of older adults — and 80% of patients aged 47 to 64 years who have underlying medical conditions — have never received a pneumococcal vaccine, which places them at a disproportionately higher risk for severe disease and death.

“Pneumococcal vaccination allows us to reduce this risk by 50% to 80%, though effectiveness varies, depending on multiple factors,” study author Giorgia Sulis, MD, PhD, an infectious disease epidemiologist and postdoctoral researcher at McGill University in Montreal, told Medscape Medical News.

“This vaccine is included in national vaccination plans in several countries, but uptake among adults remains substantially below target, suggesting that we can and must do a better job of protecting the most vulnerable,” she said.

The study was published October 14 in PLOS ONE.

Provincial Differences

Pneumonia is consistently ranked among the top ten causes of death among Canadian adults, the study authors write. Pneumococcus is the leading bacterial cause of pneumonia and can lead to other serious infections, such as meningitis and sepsis, particularly among high-risk adults.

In Canada, pneumococcal vaccination is recommended for patients aged 65 years and older, as well as for adults younger than 65 years who have one or more chronic medical conditions. The Canadian National Immunization Strategy set an 80% coverage target to be achieved by 2025, though current uptake falls short of that goal.

Sulis and colleagues analyzed self-reported data about pneumococcal vaccine uptake among 33,061 community-dwelling adults who were enrolled in the Canadian Longitudinal Study on Aging between 2015 and 2018. The research team focused on the two key groups who face high risks and fall under national vaccine recommendations — patients aged 65 years and older and adults aged 47 to 64 years with underlying medical conditions.

Overall, 45.8% of the 22,246 adults who were aged 65 years and older had never received a pneumococcal vaccine in their lifetime. Nonvaccinated people were more likely to be men, between the ages of 65 and 74 years, and a member of a racialized group. Those who hadn’t been vaccinated were also more likely to live in rural areas and Atlantic provinces (New Brunswick, Nova Scotia, Newfoundland, and Prince Edward Island). Those who lived in Quebec, Manitoba, and Alberta were more likely to be vaccinated.

About 76% of patients aged 65 years and older reported being diagnosed with at least one chronic medical condition. About 57.1% of this group reported receiving a pneumococcal vaccine, compared with 43.8% of participants who did not have an underlying condition.

Among the 10,815 adults aged 47 to 64 years with a chronic condition, 81.3% had never received a pneumococcal vaccine. Nonvaccinated people were more likely to be between the ages of 47 and 54 years and have higher incomes. Those who hadn’t been vaccinated were more likely to live in Newfoundland, compared with other provinces.

Among those with a chronic medical condition, unvaccinated rates ranged from 74.1% for those with chronic lung disease to 80.4% for those with cardiovascular disease. These conditions can increase the risk for pneumococcal disease and negative outcomes.

Notably, those who had received a flu shot or had had contact with a family doctor in the previous year were more likely to say they had received a pneumococcal vaccine.

“Missed Opportunities”

Among those who were recently vaccinated against the flu, 32.6% of patients aged 65 years and older and 71.1% of patients aged 47 to 64 years with a chronic condition didn’t get a pneumococcal vaccine.

In addition, among those who had had contact with a family doctor in the past year, 44.8% of patients aged 65 years and older and 80.4% of patients aged 47 to 64 years with a chronic condition didn’t get vaccinated.

“This very low level of vaccine uptake in this group is really striking, considering that those who have underlying conditions likely interact with the healthcare system more often than other people due to their disease,” Sulis said. “This means that there are a number of missed opportunities for vaccination.”

Sulis and colleagues are conducting additional research on pneumococcal vaccination and strategies that could increase uptake. For some groups, these strategies could include raising awareness about pneumococcal disease, vaccine eligibility, and vaccine efficacy against hospitalization and death.

“I think it’s important to underline that, with COVID-19 still circulating and resurging and the flu season starting, this is the right time to get vaccinated against pneumococcal disease as well,” Sulis said. “Pneumococcus often causes secondary infections in people who have been infected with a respiratory virus, such as the flu, increasing the risk of hospitalization and death.”

Future research should also investigate the reasons why high-risk adults don’t receive recommended pneumococcal vaccines, the study authors write. The reasons may relate to individual factors or vaccine distribution across the provinces.

Promoting Healthy Aging

Commenting on the study for Medscape, Sharifa Nasreen, MBBS, PhD, a medical epidemiologist and postdoctoral fellow at the Centre for Vaccine Preventable Diseases at the University of Toronto, said, “Pneumococcal vaccines can reduce the disease and healthcare burden and promote healthy aging among at-risk adults.”

Dr Sharifa Nasreen

Nasreen, who wasn’t involved with this study, has researched pneumococcal vaccine uptake in Canada and around the world. She and her colleagues have found that vaccine coverage remains below target levels in high-income countries and that few studies have explored the barriers to vaccination.

“Further work is warranted to better understand the reasons and barriers for pneumococcal nonvaccination from both provider and recipient perspectives,” she said. “And [researchers must] identify feasible actionable strategies to improve pneumococcal vaccine uptake among at-risk adults to aid healthy aging.”

No outside funding for this study was reported. The study was possible through data collected by the Canadian Longitudinal Study on Aging. The authors and Nasreen have disclosed no relevant financial relationships.

PLoS One. Published October 14, 2022. Full text

Carolyn Crist is a health and medical journalist who reports on the latest studies for Medscape, MDedge, and WebMD.

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