Some time ago, there were more and more voices about the rising incidence of whooping cough in 2024. The first reaction of many parents was whether their children had been vaccinated against DPT. After reading the vaccine booklet, I found out that my child had not only received DPT vaccine, but also received more than one shot, which made me feel more at ease.
But many parents will wonder: Should they continue to receive DPT vaccine in the future? Why is it that vaccines like diphtheria-tetanus-pertussis and pertussis are not given after a few injections, while vaccines like influenza need to be given once a year? Are there any particular requirements for vaccination procedures?
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Immunization programs are different
Everyone knows that vaccines are an effective means of preventing infectious diseases (and even non-communicable diseases in recent years). After vaccination, the antigens in the vaccine stimulate the body's immune system to produce corresponding humoral immunity and/or cellular immunity to defend against specific pathogens.
However, the immunization schedule of different vaccines is different. Generally speaking, the immunization schedule of a vaccine depends on the following factors:
1. Vaccine type
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Live vaccines (such as measles vaccine) usually require only 1 to 2 doses to provide long-term protection. Compared with live vaccines, similar inactivated vaccines (such as hepatitis A vaccine and Japanese encephalitis vaccine) may require more doses to achieve similar or Better immune effect.
Taking the Japanese encephalitis vaccine used in our country as an example, if you choose to vaccinate with the free live attenuated Japanese encephalitis vaccine, you need to get 2 injections, while if you choose to get the inactivated Japanese encephalitis vaccine, you need 4 injections.
2. Disease characteristics
Some pathogens may mutate, causing the immune response of previously vaccinated vaccines to be reduced or even invalid. In this case, it may be necessary to vaccinate regularly or annually with vaccines prepared using new antigens to deal with the mutated pathogens.
For example, influenza viruses may produce new strains every year due to antigenic protein mutations. Therefore, influenza vaccines prepared with new strains recommended by the World Health Organization must be vaccinated every year to obtain effective protection.
3. Immune persistence
Some vaccines (such as the measles vaccine) provide protection that lasts for many years, while others (such as the whooping cough vaccine) provide protection that weakens over time and requires booster shots to maintain immunity.
Take whooping cough as an example – a study in Zhejiang showed that among the people participating in the study, the positive rate of anti-pertussis toxin antibodies (anti-PT IgG) was the highest (81.44%) among the people aged 1 to 2 years old. After that, the antibody levels decreased rapidly; those aged 10 to 14 years old The lowest (4.72%), more than 50% of people aged 7 years and above have no detectable antibodies; the anti-PT IgG positivity rate in each age group of people aged 5 to 59 is less than 10%.
There is currently no pertussis vaccine for people aged 6 and above in my country. Therefore, after completing the full course of childhood diphtheria-tetanus vaccine (4 doses), there is no better way to prevent it except to protect yourself and keep your immune system normal.
Half-life estimates of antibodies to measles, mumps, and varicella-zoster viruses.
On the contrary, there are also some antibodies that can persist for a long time: antibodies produced after vaccination with live vaccines including measles, mumps, and chickenpox or natural infection have a very long half-life, so generally speaking, people who have followed a complete immunization program or have been infected with related viruses After that, you can obtain “lifelong immunity.”
Immunization schedules are not set in stone
In fact, most of the previous vaccines, whether live or inactivated, required more than one dose, because multiple doses can provide high-level and long-lasting protection.
However, due to the expansion of vaccine effectiveness evidence and the differences in disease risks among different groups, some multi-dose vaccine immunization schedules will also change, and even only require one dose.
For example:
1. Human papillomavirus (HPV) vaccine
Three doses of vaccination were initially recommended, but now only two doses are needed for children aged 9-14 years; the latest research finds that even one dose of HPV vaccine can provide long-lasting and reliable protection against persistent HPV infection Therefore, the World Health Organization also recommends a 1-dose vaccination schedule, and some areas have also changed the HPV vaccine immunization schedule to 1 dose.
2. Haemophilus influenzae type b (Hib) vaccine
Due to lower levels of maternally transmitted antibodies, 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 to 12 months, and in children aged 2 years The incidence rate is 1.7%. Therefore, the immunization schedule of Hib vaccine is related to age.
Hib infection-associated meningitis incidence and antibody levels in relation to age
my country’s current Hib vaccine immunization program is:
Children who start vaccination between 2 and 5 months old should receive 3 doses of basic immunization + 1 dose of booster immunization (3+1 procedure);
Children aged 6 to 11 months who start vaccination should receive 2 doses of basic immunization and 1 dose of booster immunization (2+1 procedure);
Use the 1-dose procedure for children 12 months of age and older.
Therefore, the vaccine immunization program is not constant. In addition to considering the factors of the pathogen itself, it will also comprehensively consider factors such as changes in disease burden and cost-effectiveness. However, the ultimate goal is to effectively combat the disease.
Special circumstances requiring re-vaccination
Although it is sufficient for some vaccines to complete the routine immunization schedule, there will inevitably be special circumstances that may require re-vaccination, such as cancer.
In the newly released “Vaccination of Adult Cancer Patients: ASCO Guidelines”, recommendations are made for the vaccines that adult cancer patients need to be vaccinated or re-vaccinated, which involves a variety of vaccines that need to be revoked.
Recommended vaccine information for adults with cancer Image source: “Vaccination of Adults with Cancer: ASCO Guidelines”
For example, patients begin full revaccination 6 to 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-19, influenza and pneumococcal vaccines can be given as early as 3 months after transplant.
Believe in science and timely vaccination
Vaccinations are vital for both children and adults. The vaccination program depends on many factors, including the pathogen itself, vaccine technology, health economics, individual factors, etc. Therefore, whether it is a single-dose vaccination or multiple-dose vaccination, we only need to follow the vaccine instructions or relevant guidelines Vaccination is recommended.
It should be noted that although the theme of my country’s 38th “National Children’s Vaccination Day” this year is “Working together to vaccinate to protect the entire life cycle”, we are still facing two major problems:
1. The name of the holiday on April 25 is still called “National Childhood Vaccination 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 full life cycle protection.
The current problem facing the country is that the optimization space for the vaccine system of the childhood immunization program lies in individual vaccine immunization procedures and vaccine categories, 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 domestic and foreign professional organizations, they are difficult to reach in China due to vaccine types and vaccine awareness.
It can be said that there are still many difficulties that need to be solved in the immunization of relevant groups.
In short, vaccination is an effective means of preventing infectious diseases and is of high value to the health of individuals and communities (groups). As science advances, vaccination strategies and management plans are constantly being optimized.
For ordinary people, only eight words are needed:Believe in science and get vaccinated in time.