Key Concepts: COVID-19 vaccines, including mRNA and protein-based types, are recommended for basic immunization, defined as at least three antigen exposures (vaccination or infection) for individuals aged 18 and above, and for high-risk groups such as those with chronic conditions, healthcare workers, and close contacts of immunocompromised individuals.

Limitations: Annual boosters are only recommended for high-risk groups (e.g., individuals over 60, people with chronic health conditions). For immunocompromised persons, additional doses and serological monitoring might be needed. Healthy individuals without risk factors generally do not require annual boosters.

Key Concepts: Vaccination with the 20-valent conjugate vaccine (PCV20) is recommended for individuals aged 60 and older, people with certain chronic health conditions, and those exposed to occupational hazards like metal fumes.

Limitations: Sequential vaccination (PCV20 after previous PPSV23) is no longer recommended for adults; children’s schedules remain similar. For adults previously vaccinated with PPSV23, a six-year gap before PCV20 is advised.

Key Concepts: Annual influenza vaccination is recommended in the fall, particularly for individuals aged 60 and older, those with chronic conditions, pregnant women, and healthcare personnel. A quadrivalent vaccine containing WHO-recommended strains is preferred, and a high-dose vaccine is suggested for those over 60.

Limitations: Not mandatory for everyone; mainly suggested for high-risk populations and those who could spread influenza to vulnerable individuals.

Key Concepts: Routine MenB vaccination is recommended for infants, starting as early as two months. Additional doses are given at set intervals to ensure immunity.

Limitations: Not recommended for healthy children over five or for adults without specific health conditions. Additional preventive medication may be recommended for individuals in close contact with confirmed cases.

Key Concepts: Vaccination recommended for all children and adolescents aged 9–14, ideally before the onset of sexual activity. The series can be given in two doses for younger recipients, while three doses are recommended for those starting vaccination at an older age.

Limitations: While effective against most high-risk HPV types, the vaccine does not cover all types, so routine screenings remain essential.

Key Concepts: Routine immunization schedules include Tdap for adults, with a booster every ten years, with Tdap also recommended during each pregnancy (preferably in the third trimester) to protect newborns from pertussis.

Limitations: Some adults may not require frequent boosters if they have robust immune responses from past vaccinations. Boosters are mainly aimed at maintaining herd immunity and preventing spread in vulnerable populations.

Key Concepts: The MMR vaccine is recommended for all children and adults born after 1970 who are unvaccinated or partially vaccinated. It is particularly stressed for those in high-contact professions like healthcare and education.

Limitations: For those with documented immunity or age-based natural immunity, additional doses are unnecessary. However, in outbreak settings, unvaccinated adults may still be recommended for vaccination.

Key Concepts: Vaccination is recommended for those traveling to cholera epidemic regions with likely poor access to clean water or serving as disaster relief workers.

Limitations: Effectiveness depends on hygiene conditions; vaccination does not replace safe water and food practices.

Affected Regions: Endemic areas, particularly where access to clean water is unreliable.

Key Concepts: Recommended for travelers over 4 years old with documented prior dengue infection who are visiting dengue-endemic areas.

Limitations: Not advised for "Dengue-Naive" individuals (those without prior infection) due to the risk of severe dengue upon future exposure.

Affected Regions: Tropical and subtropical regions, with current outbreak areas noted by the CDC.

Key Concepts: Immunization advised for those exposed to ticks in endemic regions, particularly in forested or grassy areas during tick season.

Limitations: Limited to tick season (typically April to November); those working in or visiting forested areas should be vaccinated.

Affected Regions: Germany, Austria, Switzerland, parts of the Baltics, and other Central European countries.

Key Concepts: Advised for extended stays in rural or endemic regions of Asia, especially if spending time near rice fields or pig farms.

Limitations: Not universally recommended due to limited exposure risk; best suited for long-term travelers in high-risk areas.

Affected Regions: Southeast Asia, parts of the Indian subcontinent, and areas with frequent outbreaks.

Key Concepts: Required for entry into certain countries; single dose provides lifelong immunity, though some groups may need a booster.

Limitations: Limited to endemic areas and only essential for those traveling to affected regions or countries with entry requirements.

Affected Regions: Sub-Saharan Africa, South America, with mandatory vaccination requirements in some countries.

Key Concepts: Recommended for travelers to regions with high rates of typhoid, particularly areas with unsafe drinking water and sanitation.

Limitations: Vaccination does not replace the need for safe water practices; effectiveness varies.

Affected Regions: South Asia, Africa, Latin America, and other regions with poor sanitation.

Key Concepts: Advised for travelers to endemic regions, especially those with close contact with locals, and high-risk populations.

Limitations: Long-term immunity requires multiple doses; Hepatitis B vaccination especially important for those in close contact with medical environments.

Affected Regions: Africa, Southeast Asia, parts of Latin America, and countries with high prevalence of hepatitis.