Pneumococcal vaccination: A public health priority
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Over the past several years, adult pneumococcal vaccine recommendations have evolved based on the development of new vaccines.
Although these changes are designed to prevent invasive pneumococcal disease (IPD), they have also introduced some confusion among clinicians and patients.
Streptococcus pneumoniae is a gram-positive bacteria with more than 100 different known serotypes. However, relatively few of these cause most IPD. Current data suggest that children aged younger than 2 years and adults aged 65 years or older have the highest rates of pneumococcal disease. The mortality rate of patients with IPD is approximately 10% but is higher among the elderly or those with underlying medical conditions or risk factors.
Widespread childhood pneumococcal vaccination in the United States has led to a steadily declining incidence of pneumococcal disease. Not only has the incidence declined in children, but IPD in adults has also declined. This phenomenon is thought to occur predominantly through reduced colonization in vaccinated infants and children, leading to reduced transmission to others. Unfortunately, pneumococcal vaccine coverage among adults is much lower than we see among children. Estimates for 2019-2020 indicate that 23.9% of people aged 19 to 64 years with risk factors for pneumococcal disease have received a pneumococcal vaccine. Although the rate of pneumococcal vaccination among people aged 65 years or older is 67.5%, this is still well below our goal. Per the HHS Vaccine National Strategic Plan, the 2030 goal for pneumococcal vaccination rates for high-risk adults aged 18 to 64 years is 70%, and it is 95% for those 65 years of age or older.
There are currently two formulations of pneumococcal vaccines, unconjugated purified polysaccharide (PPSV) and conjugated vaccine (PCV). PPSV was introduced in 1983 and contains capsular polysaccharides from 23 S. pneumoniae serotypes that have been associated with most blood and cerebrospinal fluid (CSF) infections. PCV consists of pneumococcal capsular polysaccharides that are covalently linked (ie, conjugated) to an immunogenic carrier protein. Currently, three PCV vaccines are in use — PCV 13-valent (PCV13), PCV 15-valent (PCV15) and PCV 20-valent (PCV20).
PCV13 has been in use since 2010. PCV15 and PCV20 are the newest pneumococcal vaccines, having been licensed in 2021. Although both are approved for adults, PCV15 is also licensed for use in infants and children as a primary vaccination series. Recently however, the manufacturer for PCV20 submitted a supplemental biologics license application for use in infants and children, so this vaccine may soon be available as a primary series as well.
PCV20 contains the same 13 serotypes found in PCV13, along with seven additional serotypes that account for 28% of IPD. As for PCV15, it also contains the same 13 serotypes in PCV13 and two additional serotypes, which account for approximately 13% of IPD. The incidence of the serotypes in pneumococcal pneumonia are more variable, with one study showing that 3.3% and 1.4% were caused by the additional serotypes found in PCV20 and PCV13 respectively.
Adult guidelines
The new 2022 adult pneumococcal vaccination recommendations have been simplified since the prior guidelines and should help increase vaccination rates. For adults who have not previously received a pneumococcal conjugate vaccine, the recommendations are straightforward, but recommendations are a little more complicated for those previously vaccinated or who have an underlying high-risk condition.
For those aged 65 years or older, or aged 19 to 64 years with an underlying high-risk condition, there are two options. First, one dose of PCV20 alone is sufficient for these patients. Alternatively, the CDC recommends one dose of PCV15, followed by PPSV23 after 1 year. If the patient has an immunocompromising condition, cochlear implant or CSF leak, PPSV23 can be given at a minimum of 8 weeks following PCV15 instead of waiting a full year.
There are several underlying conditions that are considered high risk for IPD. In general, high-risk conditions include immunocompromising conditions, heart disease, lung disease, liver disease, alcoholism, smoking, diabetes, cochlear implant and CSF leaks. For a full list of conditions, refer to the Advisory Committee on Immunization Practices pneumococcal vaccine recommendations.
The recommendation for those who have previously received a pneumococcal vaccine depends on which vaccine was administered before. Adults who previously received PCV13 should receive PPSV23, which is the same as recommended in the previous guidelines. However, if PPSV23 is not available, one dose of PCV20 may be used instead. It is important to note that the health benefits of using PCV15 or PCV20 in those who have been previously vaccinated with PCV13 with or without PPSV23 has not been evaluated to date. Adults who previously received only PPSV23 may receive one dose of PCV20 or PCV15 at least 1 year after their last PPSV23 dose. No additional doses of pneumococcal vaccine are necessary after PCV20 or PCV15.
Pneumococcal vaccination is not recommended for individuals aged 19 to 64 years who do not have any specific underlying medical conditions.
Timing between vaccines is important when using both PCV and PPSV23. PCV vaccines should be given first before PPSV23 to provide the greatest immune response to both vaccines. Studies have shown that when the PCV is given first, an improved immune response can be seen to serotypes common to both vaccines. In addition, shorter intervals between PCV and PPSV23 administration (less than 8 weeks) may be associated with increased local injection site reactogenicity compared with longer intervals.
Currently, revaccination with either vaccine in adults is not recommended if given before age 65 years. Although some medical providers will recommend redosing PPSV23 every 5 or so years because the potential waning of immune response, this is not currently recommended.
There can be many different pneumococcal vaccination scenarios that medical professionals may encounter in their practice due to the changing recommendations and new pneumococcal vaccines that have been released over the years. I have found Immunize.org’s “Ask the Experts” to be a valuable resource in being able to answer many these questions that may not be addressed in the ACIP recommendations.
Consumer attitudes
A recent National Foundation for Infectious Diseases survey of consumers at increased risk for pneumococcal disease revealed gaps in awareness and understanding about the vaccination and risks of pneumococcal disease.
Less than half of the respondents were familiar with pneumococcal disease. One of the most concerning details of the survey was that only 29% of those at increased risk had been advised to get a pneumococcal vaccine. However, among those who were advised to get a vaccine, most went on to get vaccinated.
These data highlight the fact that health care providers need to educate their patients about the risks of pneumococcal disease and the benefits of vaccination. In order to meet the 2030 goals for pneumococcal vaccination, health care professionals must focus on interventions to increase pneumococcal vaccination among their patients.
- References:
- El-Beyrouty C, et al. Pharmacotherapy. 2022; doi:10.1002/phar.2723.
- Gierke R, et al. Manual for the Surveillance of Vaccine-Preventable Diseases, Chapter 11: pneumococcal; https://www.cdc.gov/vaccines/pubs/surv-manual/chpt11-pneumo.html.
- HHS. Vaccines National Strategic Plan 2021–2025. Washington, D.C. https://www.hhs.gov/sites/default/files/HHS-Vaccines-Report.pdf.
- Immunize.org. Ask the experts – Pneumococcal vaccines. https://www.immunize.org/askexperts/experts_pneumococcal_vaccines.asp.
- Kobayashi M, et al. MMWR Morb Mortal Wkly Rep. 2022;doi: 10.15585/mmwr.mm7104a1.
- Kobayashi M, et al. MMWR Morb Mortal Wkly Rep. 2022;doi: 10.15585/mmwr.mm7137a3.
- Musher DM, et al. Pneumonia. 2022;doi:10.1186/s41479-022-00097-y.
- National Foundation for Infectious Diseases. 2022 National Survey: Attitudes about influenza and pneumococcal disease, and the impacts of COVID-19; https://www.nfid.org/about-nfid/newsroom/news-conferences/2022-nfid-influenza-pneumococcal-disease-news-conference/2022-national-survey-attitudes-about-influenza-and-pneumococcal-disease-and-the-impacts-of-covid-19/.
- For more information:
- Jeff Brock, PharmD, MBA, BCIDP, is an infectious disease pharmacy specialist at Mercy Medical Center in Des Moines, Iowa. He can be reached at jbrock@mercydesmoines.org.
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