Is the 23-valent pneumonia vaccine useless? You really don't take this vaccine seriously, which is still active in the latest recommendations.

Part 1: Effective but with a large range

During the COVID-19 pandemic, the Danish government launched a vaccination program for people over 65 years old to prevent invasive pneumococcal disease (IPD) using the 23-valent pneumococcal polysaccharide vaccine (PPSV23).

The program began on April 22, 2020, initially targeting people aged 65 and over who were at high risk for IPD (for example, those with chronic lung or heart disease). On June 15, 2020, the program was expanded to include all people aged 65 and over and will run until January 15, 2023.

In the first year of the program, 61% of Danish residents aged 65 years and over were vaccinated with PPSV23. During the study period, the most common IPD-causing serotypes in the Danish population aged 65 years and over were serotype 3 (19%), serotype 8 (12%), and serotype 22F (7%), all of which are covered by PPSV23.

Early studies have shown that PPSV23 has some efficacy against IPD caused by the included serotypes in people older than 60 years, although the confidence intervals for the efficacy were wide, ranging from 24% (95% CI 10%–36%) to 72% (95% CI 46%–85%) (9–15).

Part II: Effectively reducing risks for the elderly

As a follow-up to the first year of the study, the researchers also conducted a follow-up study within the Danish vaccination program.

In a follow-up study, the researchers counted the protective effect (VE) of PPSV23 against IPD in 1,254,498 people aged 65 and above from April 2020 to January 2023, and evaluated it using a Cox regression model and adjusted for age, gender, and underlying diseases.

Based on nationwide data from Denmark, the researchers estimated that the VE of PPSV23 against all types of IPD was 32% and the VE against PPSV23 serotype IPD was 41%.

Because this follow-up study had higher statistical power than the original study, the researchers also estimated these numbers:

①PPSV23 serotypes overall (excluding type 3);

② Type 3, Type 8, Type 22F (these three are the main serotypes in Denmark);

③Serotypes covered by PPSV23 but not by 15-valent pneumococcal conjugate vaccine (PCV15);

④Serotypes covered by PPSV23 but not by 20-valent pneumococcal conjugate vaccine (PCV20);

⑤VE of IPD in different time periods.

Conclusions: PPSV23 vaccination can protect people aged 65 years and older from IPD caused by all serotypes or serotype groups except type 3.

In other words, the 23-valent vaccine can truly protect the elderly. In my country, PPSV23 can be used for people aged ≥2 years, and is also the only choice for people aged ≥5 years to prevent invasive pneumococcal infections.

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Disclaimer: This article was created out of personal interest, only to help more ordinary people have a clearer understanding of vaccines. The content and views do not represent any organization, unit, or institution, and it has not accepted any form of sponsorship. All pictures are from public online platforms. If the content is incorrect, please do more self-criticism (not).