Pneumococcal Vaccine: Types, Side Effects, and Who Needs It

Introduction

Pneumonia is a broad term that refers to lung infections caused by various organisms, including bacteria, viruses, and fungi¹. Normally, the lungs contain tiny air sacs called alveoli that fill with air during breathing. In pneumonia, these alveoli become inflamed and filled with pus and fluid. This makes breathing difficult and reduces oxygen intake².  

The infection typically spreads when a person breathes in respiratory droplets or accidentally inhales secretions from the mouth or throat (when an infected person coughs or sneezes)². Pneumonia can range from mild to life-threatening, with the highest risk seen in infants, older adults, individuals with weakened immune systems, patients with chronic illness (such as diabetes), smokers, and patients on ventilators^1,3. 

Fortunately, pneumonia (when caused by bacteria) can be prevented with vaccines. In this article, we will explore what pneumococcal vaccines are, how they work, and who should receive them. 

What Is Pneumococcal Vaccine?

As mentioned, pneumonia is a respiratory infection caused by bacteria, fungi or viruses. More commonly, it occurs due to infection with the bacteria Streptococcus pneumoniae (also known as pneumococcus). Infection with this organism can lead to serious illnesses such as pneumonia, sinusitis, ear infections (otitis media), and meningitis. These infections remain a significant cause of illness and death, even in high-income countries⁴.  

More than 90 distinct pneumococcal serotypes have been identified, and while many are capable of causing illness, only a subset is responsible for the majority of severe and invasive pneumococcal diseases⁵. 

Pneumococcal vaccines help prevent these infections in the body by developing immunity against them. These vaccines contain parts of the bacteria (specifically capsular polysaccharides) either alone or linked to a carrier protein, which trigger the immune cells to produce antibodies that fight against specific pneumococci strains. Let us discuss about this in detail in the next section. 

How Do Pneumococcal Vaccines Work?

Pneumonia or Pneumococcal vaccines help the body develop active immunity by training the immune system to recognise and combat certain serotypes of Streptococcus pneumoniae bacteria. There are two types of pneumococcal vaccines currently in use, which include:  

• Conjugated vaccines (PCV): These use a carrier protein to attach to the bacterial capsular polysaccharides and enable the body to produce both B-cell and T-cell immune responses. This results in longer-lasting immunity. PCV can help reduce bacteria in the nose and throat (nasopharyngeal carriage), which lowers the risk of spreading the infection (polysaccharide vaccines (PPSV) does not have this effect)^6,7. 
• Unconjugated or Polysaccharide vaccine (PPSV): This consists of the polysaccharide alone and produces a weaker and shorter-lasting immune response than PCVs because it triggers B-cell responses without the help of T-cells, which means it doesn’t create long-term immune memory. As a result, PCVs provide stronger and more lasting protection. However, PPSV covers more serotypes than PC vaccines⁶. 

After vaccination, the immune system generates targeted antibodies against the specific pneumococcal serotypes present in the vaccine, helping to protect the body from future infections caused by those strains.  

Types of Pneumococcal Vaccines

Pneumococcal vaccines are available in two main formulations: PCV and PPSV. Let us see how they differ in covering different serotypes. 

1. PCV13 (13-valent pneumococcal conjugate vaccine) [Prevnar 13]

• Safeguards against 13 common pneumococcal serotypes: 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F³. 

2. PCV15 (15-valent pneumococcal conjugate vaccine) 

• Covers the same 13 serotypes as PCV13, plus two additional serotypes: 22F and 33F³. 

3. PCV20 (20-valent pneumococcal conjugate vaccine) 

• Includes all PCV13 serotypes and adds seven more: 8, 10A, 11A, 12F, 15B, 22F, and 33F. 
• Provides broader protection, especially recommended for older adults and individuals with risk factors³.

4. PPSV23 (23-valent pneumococcal polysaccharide vaccine) [Pneumovax 23]

• Covers 23 serotypes, such as 1, 2, 4, 3, 5, 6B, 7F, 8, 9N and 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19A and 19F, 20, 22F, 23F, and 33F. 
• Often administered after a conjugate vaccine (with PCV 13 or 15) to enhance coverage and boost memory immunity which is not possible with PPSV23 alone^3,8. 

Note:  

• PCVs are routinely given to children under 5 and to older children or adults with certain health conditions, including all adults ≥65 years⁸. 
• PPSV23 is recommended for children aged 2 to 18 with specific medical risks and for adults as a follow-up to PCV15 or based on prior vaccination status⁸. 
• As per recent Centers for Disease Control and Prevention/Advisory Committee on Immunization Practices (CDC/ACIP) guidelines: 
• Adults ≥65 years and those 19 to 64 with certain risk factors (e.g., immunocompromised) should receive either: 
• PCV20 alone (no PPSV23 needed), or 
• PCV15 followed by PPSV23 
• 1 year later in healthy (immunocompetent) individuals 
• 8 weeks later in high-risk/immunocompromised individuals 
• PPSV23 may also be given in previously vaccinated individuals to address timing or coverage gaps³. 

It’s best to consult a doctor to determine the appropriate vaccine and schedule based on age, health status, and medical history. 

How Effective are Pneumococcal Vaccines

Clinical studies have demonstrated strong immune responses and significant protection against vaccine-covered serotypes^9,10. Top pneumococcal vaccine uses​ include: 

• Reducing the risk of severe pneumonia and invasive pneumococcal diseases (bacterial origin)³. This may lead to reduced hospitalisations and deaths. 
• PCVs reduce bacterial carriage in the nasopharynx, which helps lower transmission rates within communities¹¹. These vaccines induce robust and long-lasting immune responses due to T-cell involvement. 
• PPSV23 offers broad coverage against numerous serotypes and effectively prevents serious infections in adults (although short lived)^3,6. 

Overall, widespread vaccination has led to a marked decline in pneumococcal infections globally and continues to be a critical tool in preventing pneumonia and its complications. 

Who Should Get the Pneumococcal Vaccine?

The CDC recommends pneumococcal vaccines for: 

• Children: 
• All children under 5 years of age¹². 
• Children aged 5 to 18 years with certain medical conditions (e.g., chronic heart or lung disease, diabetes, or weakened immunity^3,12. 
• Adults: 
• All adults aged ≥65 years and older³.
• Adults aged 19 to 64 years should only get vaccinated if they have specific health risks (such as chronic illnesses, immunocompromised status, or lifestyle factors)^3,12. 

Who Shouldn’t Get the Pneumococcal Vaccine?

Some individuals may need to avoid pneumococcal vaccination or should first consult their doctor. The CDC recommends avoiding or delaying vaccination in the following conditions. 

For PCV15, PCV20, or PCV21: 

• History of a life-threatening allergic reaction to any PCV. 
• Severe allergy to any vaccine containing diphtheria toxoid (e.g., DTaP). 
• Known severe allergy to any other component of the PCV vaccines⁸. 

For PPSV23: 

• Children younger than 2 years old. 
• History of a life-threatening allergic reaction to PPSV23 (a previous dose). 
• Known severe allergy to any ingredient in PPSV23⁸.

Tip: Always talk to a doctor about your vaccination history, allergies, and medical conditions before getting vaccinated. 

Side Effects of Pneumococcal Vaccines

Most pneumococcal vaccine side effects are mild and temporary. They may vary slightly by vaccine type and age group³: 

• Injection Site Reactions: Pain, redness, swelling, tenderness, or hardness at the site of injection (commonly reported across all age groups for PCV13, PCV15, PCV20, and PPSV23). 
• General Symptoms: Fatigue, headache, muscle pain (myalgia), joint pain (arthralgia), and low-grade fever may occur. 
• Less Common Reactions: Vomiting, chills, rash, and limited arm movement may occasionally occur, especially in adults after PCV13. 

These side effects typically resolve on their own. If severe or persistent symptoms occur, it’s important to consult a healthcare provider. 

When to See a Doctor

While most pneumococcal vaccine side effects are mild, you should contact a doctor or seek medical attention immediately if you experience: 

• Signs of a severe allergic reaction (anaphylaxis), such as difficulty breathing or swelling of the face or throat³ 
• High fever  
• Worsening of symptoms (mentioned above) 
• Prolonged pain, swelling, or redness at the injection site 

Always consult your doctor if you’re unsure whether a symptom is vaccine-related or if you’re concerned about any reaction. 

Conclusion

The pneumococcal vaccine plays a vital role in protecting individuals (especially young children, older adults, and those with certain health conditions) from serious and potentially life-threatening infections caused by Streptococcus pneumoniae. Pneumococcal vaccine uses conjugate and polysaccharide formulations to build immunity against multiple strains of the bacteria, significantly reducing the risk of severe pneumonia, hospitalisations, and complications such as meningitis and bloodstream infections.  

Widespread vaccination not only safeguards individual health but also helps reduce the spread of pneumococcal disease within communities, making it an essential part of public health protection! 

Frequently Asked Questions (FAQs)

References

1. Jain V, Vashisht R, Yilmaz G, Das S. Pneumonia Pathology [Internet]. StatPearls Publishing; 2025 Jan; [updated 2023 Jul 31; cited 2025 Jun 6]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526116/ 
2. World Health Organization. Pneumonia [Internet]. World Health Organization; [cited 2025 Jun 6]. Available from: https://www.who.int/health-topics/pneumonia 
3. Tereziu S, Minter DA. Pneumococcal Vaccine [Internet]. StatPearls Publishing; 2025 Jan; [updated 2023 Mar 20; cited 2025 Jun 6]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507794/ 
4. Pletz MW, Maus U, Krug N, Welte T, Lode H. Pneumococcal vaccines: mechanism of action, impact on epidemiology and adaption of the species. Int J Antimicrob Agents. 2008 Sep;32(3):199-206. Available from: https://pubmed.ncbi.nlm.nih.gov/18378430/ 
5. Wantuch PL, Avci FY. Current status and future directions of invasive pneumococcal diseases and prophylactic approaches to control them. Hum Vaccin Immunother. 2018;14(9):2303-2309. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC6183136/ 
6. Golos M, Eliakim‐Raz N, Stern A, et al. Conjugated pneumococcal vaccine versus polysaccharide pneumococcal vaccine for prevention of pneumonia and invasive pneumococcal disease in immunocompetent and immunocompromised adults and children. Cochrane Database Syst Rev. 2019 Feb 20;2019(2)S:CD012306. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC6381862/ 
7. Kim YK, LaFon D, Nahm MH. Indirect Effects of Pneumococcal Conjugate Vaccines in National Immunization Programs for Children on Adult Pneumococcal Disease. Infect Chemother. 2016 Dec;48(4):257-266. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC5204004/ 
8. Centers for Disease Control and Prevention. Types of Pneumococcal Vaccines [Internet]. Centers for Disease Control and Prevention; [cited 2025 Jun 6]. Available from: https://www.cdc.gov/pneumococcal/vaccines/types.html 
9. Nakafero G, Grainge MJ, Card T, et al. Effectiveness of pneumococcal vaccination in adults with common immune-mediated inflammatory diseases in the UK: a case-control study. Lancet Rheumatol. 2024 Sep;6(9):e615-e624. Available from: https://pubmed.ncbi.nlm.nih.gov/39067457/ 
10. Dunne EM, Cilloniz C, von Mollendorf C, et al. Pneumococcal Vaccination in Adults: What Can We Learn From Observational Studies That Evaluated PCV13 and PPV23 Effectiveness in the Same Population? Arch Bronconeumol. 2023 Mar;59(3):157-164. English, Spanish. Available from: https://pubmed.ncbi.nlm.nih.gov/36681604/ 
11. Kahn R, Moiane B, Lessa FC, et al. Nasopharyngeal carriage of Streptococcus pneumoniae among children and their household members in southern Mozambique five years after PCV10 introduction. Vaccine. 2025 Feb 15;47:126691. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC11797556/ 
12. Centers for Disease Control and Prevention. Pneumococcal Vaccination [Internet]. Centers for Disease Control and Prevention; [cited 2025 Jun 6]. Available from: https://www.cdc.gov/pneumococcal/vaccines/index.html 

Disclaimer: The information provided here is for educational/awareness purposes only and is not intended to be a substitute for medical treatment by a healthcare professional and should not be relied upon to diagnose or treat any medical condition. The reader should consult a registered medical practitioner to determine the appropriateness of the information and before consuming any medication. PharmEasy does not provide any guarantee or warranty (express or implied) regarding the accuracy, adequacy, completeness, legality, reliability or usefulness of the information; and disclaims any liability arising thereof.