In late June, ACIP, the advisory committee to the CDC, recommended a single dose of pneumococcal conjugate vaccine 21 (PCV21) as an option for adults aged 19 years and older for whom PCV is currently recommended.
While indications for PCV have not changed from previous recommendations, a recent article in the CDC’s Morbidity & Mortality Weekly Report explained why that recommendation was made just days after the FDA approved PCV21, which is marketed as Capvaxive by Merck Sharp & Dohme (LLC), for adults aged ≥18 years.
“PCV21 does not contain certain serotypes that are included in other licensed pneumococcal vaccines but adds eight new serotypes,” according to article authors.
ACIP recommended use of a PCV for all adults aged 65 years and older, as well as adults aged 19 to 64 years with certain risk conditions for pneumococcal disease if they have not received a PCV or whose vaccination history is unknown. Previously, the sometimes-confusing options included either 20-valent PCV (PCV20; Prevnar20; Wyeth Pharmaceuticals, Inc.) alone or a 15-valent PCV (PCV15; VAXNEUVANCE; Merck Sharp & Dohme, LLC) in series with 23-valent pneumococcal polysaccharide vaccine (PPSV23; Pneumovax23; Merck Sharp & Dohme, LLC). Additional recommendations for use of PCV20 exist for adults who started their pneumococcal vaccination series with 13-valent PCV (PCV13; Prevnar13; Wyeth Pharmaceuticals, Inc.).
So why the change with a newly approved vaccine?
“Before the COVID-19 pandemic, approximately 100,000 noninvasive pneumococcal pneumonia hospitalizations and 30,000 IPD [invasive pneumococcal disease] cases occurred annually among U.S. adults,” according to the article. “During 2018–2022, pneumococcal serotypes contained in PCV21 caused approximately 80% of IPD cases among adults with indications for vaccination, including 20%-30% due to the eight new serotypes contained in PCV21.”
The article added that serotype 4, a serotype contained in other licensed pneumococcal vaccines currently in use (PCV15, PCV20, and PPSV23), is not included in PCV21.
Background information advised that after introduction of the 7-valent PCV in children, serotype 4 IPD significantly declined but is reemerging recently as a cause of IPD in certain regions, especially the western United States, including Alaska, Colorado, New Mexico, Oregon, and the Navajo Nation.
“Affected persons at risk for serotype 4 IPD are typically adults aged <65 years with a risk condition, with history of substance abuse, or who are experiencing homelessness,” the CDC authors explained.
The authors also pointed out that “incidence of pneumococcal disease is disproportionately higher in black or African American (black) adults than in non-black adults, resulting in high U.S. societal costs. The introduction of PCV13 among U.S. children reduced disparities that existed in PCV13-type IPD incidence in adults, likely because of indirect effects from PCV13 vaccination in children; remaining racial disparities are primarily due to disease caused by non-PCV13 serotypes.”
In essence, the ACIP decided that adding PCV21 as an option in the current PCV recommendation should help prevent additional disease caused by pneumococcal serotypes unique to PCV21. Future recommendations will depend on postlicensure monitoring of the safety of the vaccine and its public health impact, according to the committee.
The CDC noted that streptococcus pneumoniae (pneumococcus) is a common bacterial cause of respiratory tract infections, bacteremia, and meningitis. IPD, a pneumococcal infection in a normally sterile site (e.g., blood, cerebrospinal fluid, bone, or joint space), can result in severe morbidity or mortality. Adults with certain underlying conditions or risk factors that increase the risk for pneumococcal disease (risk conditions) and those aged ≥65 years are at increased risk and have experienced IPD case fatality ratios exceeding 10%.
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