Vaccination is a preventive medical measure that introduces antigens into the human body via injection or inhalation, primarily aiming to stimulate the immune system to produce specific antibodies, thereby establishing active immunity against particular infectious diseases. Since its development in the late 18th century, vaccination has become one of the most central strategies in global public health systems to combat infectious diseases. Modern vaccine technologies not only include traditional inactivated vaccines but also innovative forms such as mRNA and vector vaccines, suitable for all age groups and health conditions.
The core value of vaccination lies in achieving herd immunity through individual immunization, effectively interrupting the transmission chain of infectious diseases. The World Health Organization (WHO) recommends that countries develop regular immunization schedules based on epidemiological data and rapidly develop specialized vaccines for emerging infectious diseases. This approach is non-invasive, highly safe, and cost-effective, making it a cornerstone of public health.
Vaccines are mainly classified into inactivated vaccines, live attenuated vaccines, subunit protein vaccines, mRNA vaccines, and viral vector vaccines. Inactivated vaccines contain pathogens that have lost infectivity, safely inducing cellular and humoral immune responses; mRNA vaccines deliver RNA encoding pathogen proteins via lipid nanoparticles, prompting host cells to produce antigens to train the immune system. After vaccination, antigen components are processed by antigen-presenting cells, activating B lymphocytes and T lymphocytes recognition and memory mechanisms.
Next-generation vaccines such as protein subunit vaccines directly use key proteins on the surface of pathogens, avoiding the risks associated with live viruses. Booster doses are used to respond to waning antibody levels by re-stimulating memory cells to restore protection. Special populations, such as immunocompromised patients, may require adjusted dosing schedules and quantities.
Vaccination is primarily used to prevent viral and bacterial infectious diseases, including influenza, COVID-19, tetanus, pertussis, human papillomavirus (HPV), and chickenpox. Routine childhood immunizations cover vaccines against Haemophilus influenzae type b (Hib), rotavirus, and others, while adults may require rabies pre-exposure prophylaxis or shingles vaccines. Special groups such as healthcare workers or international travelers may need additional vaccines like yellow fever or Japanese encephalitis.
New vaccines such as experimental Zika virus vaccines are in clinical trials, and therapeutic cancer vaccines are in breakthrough development stages. For high-risk groups, personalized vaccination strategies incorporating genotyping are gradually becoming popular, such as prioritizing certain meningococcal vaccine types for specific blood groups.
Vaccination routes include intramuscular injection, subcutaneous injection, and spray inhalation. Routine pediatric vaccines are often administered into the lateral thigh muscle, while adult influenza vaccines are mainly injected into the deltoid muscle of the upper arm. Dosage calculations depend on age, weight, and vaccine type; for example, the primary series of COVID-19 mRNA vaccines involves two doses spaced 3 to 8 weeks apart, with booster doses recommended for those over 65 to enhance immunity.
Special considerations include that preterm infants should be vaccinated according to corrected age, and immunosuppressed patients may require increased doses or more frequent vaccinations. Pregnant women should follow the latest guidelines from the Ministry of Health and Welfare; for instance, BNT vaccines administered during the third trimester can provide passive immunity to the fetus. Patients with autoimmune diseases should consult with their physicians before receiving live vaccines to evaluate medication use.
Economically, each vaccine dose prevents costs that are over a hundred times the subsequent treatment expenses. Innovative vaccine platforms like mRNA can rapidly develop strain-specific vaccines; for example, the Omicron-specific vaccine development cycle was shortened to within six months in 2023. For patients with chronic diseases, pneumococcal vaccines can reduce hospitalization rates by up to 40%.
Common local reactions include redness, swelling, pain at the injection site, and mild fever, occurring in approximately 10-15% of cases, usually resolving within 24-48 hours. Rare allergic reactions such as anaphylaxis have an incidence of less than five per million doses, with emergency equipment like adrenaline available at vaccination sites. mRNA vaccines may slightly increase the risk of myocarditis, particularly in adolescent males after the second dose, but the incidence remains below 0.1%.
Long-term studies show that proper vaccination is not associated with autoimmune diseases or severe sequelae. Data from 2023 indicate no significant difference in the incidence of neurological adverse events compared to background levels. Individuals with a history of severe allergies should be vaccinated under medical supervision and observed for 30 minutes post-vaccination for immediate reactions.
Absolute contraindications include severe allergies to vaccine components (e.g., those allergic to tetanus toxoid in DTaP) and a history of immediate hypersensitivity reactions post-vaccination. Relative contraindications include acute fever (temperature >38.5°C), ongoing immunosuppressive therapy (such as high-dose steroids), and preterm infants weighing less than 1500 grams. Pregnant women should evaluate based on vaccine type; for example, IPV (inactivated poliovirus vaccine) is safe, while live yellow fever vaccine should be postponed until postpartum.
Prior to vaccination, actively disclose any history of vaccine reactions, chronic disease control status, and recent medications to the healthcare provider. Special cases such as HIV carriers with CD4+ T cell counts below 200/μL should avoid live attenuated vaccines. Post-vaccination, avoid strenuous exercise for 24 hours to reduce the risk of local reactions.
Immunosuppressants like corticosteroids may reduce vaccine-induced immune responses; it is recommended to discontinue or adjust doses four weeks prior to vaccination. Biologics such as TNF-α inhibitors may require delaying live vaccines until three months after cessation. Follow the 'simultaneous vaccination guidelines' when administering other injectable treatments, such as combining pertussis, tetanus, and diphtheria vaccines with influenza vaccines.
Patients who have received plasma products should delay viral vaccine administration for at least three months to prevent interference from plasma antibodies. Cancer patients undergoing chemotherapy should carefully evaluate vaccination timing; some studies suggest that administering tetanus vaccines at least two weeks apart from chemotherapy maintains immune efficacy. No significant interactions have been observed between new mRNA vaccines and anticoagulants, but injection site hematomas should be monitored.
Clinical trials show that mRNA COVID-19 vaccines maintain over 75% protection against severe disease caused by the Omicron variant, with booster doses increasing neutralizing antibody titers to 5-10 times the baseline. Influenza vaccines offer about 40-60% annual protection but significantly reduce hospitalization and mortality. When vaccination coverage reaches 95%, herd immunity can be established, effectively blocking virus transmission.
Long-term follow-up studies confirm that BCG not only prevents tuberculosis but also modulates innate immunity to reduce the risk of other bacterial infections. The 13-valent pneumococcal conjugate vaccine provides over 80% protection against invasive infections, and in those over 65, it reduces invasive disease rates by 60-75%. Although antibody responses in cancer patients after influenza vaccination are 15-20% lower than in the general population, they still significantly reduce complication risks.
Individuals unable to receive vaccines may consider passive immunity options such as immunoglobulin injections or antibody plasma therapy, which provide short-term protection requiring repeated administration. For those allergic to egg proteins, egg-free influenza vaccines or non-embryonated cell culture vaccines are available. Immunocompromised patients can receive higher doses (e.g., 4-fold hepatitis B vaccine) to ensure adequate immune response.
Limitations of passive immunity include only providing protection for 6-12 weeks and not replacing active immune memory. For severe allergies to specific antigens, skin testing can evaluate the feasibility of desensitization with allergen-free vaccines. New vaccine types like DNA vaccines and nanoparticle vector vaccines offer alternatives for those hesitant about traditional vaccines but must follow approved vaccination guidelines.
Generally, healthy adults can receive vaccines directly, but those with chronic diseases (such as heart disease, immune system disorders) or undergoing cancer treatment should consult their physician first. The doctor will evaluate drug interactions or allergy history to ensure safety.
What should I do if I develop a fever or fatigue after vaccination?Mild fever or muscle soreness are common reactions. Taking recommended antipyretics (such as acetaminophen), resting, and staying hydrated can help. If high fever persists beyond 48 hours, or if breathing difficulty or severe hives occur, seek medical attention immediately.
Can I engage in vigorous exercise immediately after vaccination?It is advisable to avoid strenuous activity within 24 hours post-vaccination to prevent increased pain or fatigue at the injection site. Light activities like walking are acceptable, and monitoring body reactions ensures stable immune response.
Are the protective effects of different vaccine brands the same? How should I choose?Protection rates vary among vaccine brands based on research data, but WHO recommends using versions that match circulating strains. If allergic to specific components, choose non-vector or component-free vaccines according to current health guidelines.
How long does immunity last after vaccination? Are booster doses necessary?Vaccine protection varies by individual immune response. Typically, immunity wanes 6 to 12 months after primary vaccination, and booster doses can effectively elevate antibody levels. Regular assessment based on viral mutation trends and personal exposure risk is advised to determine the need for additional doses.
%201.svg)
Copyright © 2025 MedFrontiers. All Rights Reserved.
