Some time ago, there were more and more voices about the rise in the incidence of whooping cough in 2024, and the first reaction of many parents was whether their children had been vaccinated against diphtheria, tetanus, te After reading the vaccine booklet, I found that the child had not only received the diphtheria-tetanus-pertussis vaccine, but also had more than one injection, and his heart was suddenly more steady.
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However, many parents will wonder: should they continue to get the diphtheria-pertussis vaccine in the future? Why do they not get a vaccine like diphtheria-pertussis after a few shots, while a vaccine like the flu should be given once a year? Is there anything special about the immunization schedule of the vaccine?
Immunization schedules are different
Everyone knows that vaccines are an effective means of preventing communicable diseases, even non-communicable diseases in recent years. The antigens in the vaccine after vaccination protect against specific pathogens by stimulating the body's immune system to produce corresponding humoral and/or cellular immunity.
However, the immunization schedule varies from vaccine to vaccine, and generally speaking, the immunization schedule of the vaccine depends on the following factors:
1
Type of vaccine
Live vaccines (e.g., measles vaccines) usually provide long-term protection with only 1 to 2 doses, and more doses may be required to achieve similar or better immune outcomes than comparable inactivated vaccines (e.g., hepatitis A, Japanese encephalitis vaccines).
For example, if you choose to receive the free live attenuated JE vaccine, you need 2 shots, while 4 shots are required to receive the inactivated JE vaccine.
2
Disease characteristics
In some pathogens, there will be mutations that can lead to a reduced or even ineffective immune response to previous vaccines, in which case regular or annual vaccinations with neoantigens may be required to respond to the mutated pathogens.
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For example, influenza viruses may produce new strains every year due to antigenic protein mutations, so it is necessary to receive influenza vaccines prepared with new strains recommended by the World Health Organization every year to obtain effective protection.
3
Immune Endurance
Some vaccines, such as the measles vaccine, provide protection that lasts for years, while others, such as the pertussis vaccine, may provide protection that wanes over time and requires a booster shot to maintain immunity.
Taking pertussis as an example, a study in Zhejiang showed that among the people participating in the study, the positive rate of anti-pertussis toxin antibody (anti-PT IgG) was the highest (81.44%) in the 1~2 years old, and the antibody level decreased rapidly after that, the lowest (4.72%) in the 10~14 years old, and more than 50% of the people aged 7 and above could not detect antibodies, and the positive rate of anti-PT IgG in all age groups of 5~59 years old was less than 10%.
At present, there is no pertussis vaccine for people aged 6 years and older in the mainland, so after completing the full course of diphtheria-pertussis vaccine in children (4 doses), there is no better way to prevent it except to protect and maintain a normal immune system.
Half-life estimates of antibodies to measles, mumps, varicella-zoster virus. Image source: Reference[3]
In contrast, there are some antibodies that can be long-lasting: antibodies produced after live vaccinations such as measles, mumps, and chickenpox, or natural infection, have an extremely long half-life, so they generally achieve "lifelong immunity" after following a complete immunization schedule or after being infected with the virus in question.
Immunization schedules are not set in stone
In fact, most vaccines, both live and inactivated, have previously been administered with more than 1 dose, as multiple doses provide a high level of long-lasting protection.
However, due to the expansion of evidence on vaccine effectiveness and differences in disease risk among different populations, the immunization schedule of some multi-dose vaccines will also change, and even only 1 dose will be required.
For example:
1
Human papillomavirus (HPV) vaccine
Three doses were originally recommended, but for children aged 9 to 14 years, only two doses are now required, and the World Health Organization has also recommended a one-dose schedule, and some regions have changed the HPV vaccine schedule to a one-dose schedule, according to recent research that found that even one dose of HPV vaccine provides long-lasting and reliable protection against persistent HPV infection.
2
b 型流感嗜血杆菌（Hib）疫苗
Due to the decrease in maternal antibody levels, the prevalence of Hib infection increases rapidly from 4 months of age but begins to decline after 1 year of age—98.3% of Hib meningitis occurs in children aged 2~12 months, and the incidence rate in children aged 2~12 months is 1.7%. Therefore, the immunization schedule of the Hib vaccine is age-related.
Incidence of meningitis associated with Hib infection and antibody levels in relation to age Credit: Reference [8]
The current HIB vaccine immunization schedule in mainland China is:
Children who started vaccination at the age of 2~5 months were given 3 shots of primary immunization + 1 booster dose (3+1 procedure);
Children who started vaccination at the age of 6~11 months were given 2 doses of primary immunization and 1 dose of booster immunization (2+1 procedure);
A 1-needle procedure is used for children 12 months of age and older.
Therefore, the immunization schedule of the vaccine is not constant, in addition to the factors of the pathogen itself, it will also take into account factors such as changes in disease burden and cost-effectiveness, but the ultimate goal is to fight the disease efficiently.
Special circumstances that require revaccination
Although some vaccines are sufficient to complete the routine immunization schedule, there are inevitably special circumstances that may require revaccination, such as cancer.
The latest release of Vaccination for Adult Cancer Patients: ASCO Guidelines recommends vaccines that require or revaccination for adult cancer patients, including a variety of vaccines that require revaccination.
Information on Recommended Vaccines for Adult Cancer Patients Image Credit: Vaccination of Adult Cancer Patients: ASCO Guidelines
For example, patients begin full revaccination 6-12 months after hematopoietic stem cell transplantation to restore vaccine-induced immunity. Live vaccines should be deferred for at least 2 years and given only in the absence of active graft-versus-host disease (GvHD) or immunosuppression. COVID, flu, and pneumococcal vaccines can be given as early as 3 months after transplantation.
Believe in science
Get vaccinated in time
Vaccination is essential for both children and adults. The immunization schedule of the vaccine depends on a variety of factors, involving the pathogen itself, the vaccine process, health economics, individual factors, etc., so whether it is a single dose of vaccination or multiple doses, we only need to follow the vaccine instructions or relevant guidelines to administer the vaccine.
It should be noted that although the theme of the 38th "National Child Immunization Day" in mainland China this year is "Joint Action to Vaccinate and Escort the Whole Life Cycle", there are still two major problems:
1. The name of the holiday on April 25 is still called "National Child Immunization Day" instead of "National Immunization Awareness Day";
2. The vaccination system for the adult population has not yet been established, and it is difficult to support the protection of the whole life cycle.
At present, the problem in China is that the optimization space of the vaccine system of the childhood immunization program lies in the immunization program and vaccine category of individual vaccines, while the adult vaccination system has not yet been established. In addition, although the immunization recommendations for some special groups (such as pregnant women, cancer patients, etc.) have been supported by professional institutions at home and abroad, it is difficult to reach them in China due to vaccine types and vaccine awareness.
It can be said that there are still a number of difficulties in immunization of relevant groups that need to be solved urgently.
In conclusion, vaccination is an effective means of preventing infectious diseases and is of great value to the health of both individuals and communities (groups). With the advancement of science, the vaccination strategy and management plan of the vaccine are also constantly optimized.
For ordinary people, there are only eight words to do: believe in science and get vaccinated in time.