Is it better for children to be vaccinated as early as possible?

In recent days, you may have noticed that there are more and more cases of influenza, herpetic pharyngitis, mycoplasma feiyan, and acute pharyngitis around you. Why? In fact, it is just because it is the season with the highest incidence of infectious diseases.

Whenever this happens, I always stand in awe of the great invention of vaccines. With this powerful plug-in, some notorious infectious diseases have disappeared or kept a low profile. Especially for newborns, during their critical growth period after birth, vaccines are like a shield in front of the baby, ensuring that children are not attacked by infectious diseases that are common in infants and young children. Today, let's talk about vaccines.

01. Why should we get vaccinated?

There is no doubt that children are the future of the family, the country, and even the entire society. For this reason, regardless of the system, region, or race, every country will formulate a special immunization plan to protect the growth of newborns. This is also the case in my country, and even more so. Take a look at my country's child immunization plan (see the figure below), which basically covers all kinds of infectious diseases that you know and those that you are completely unknown to you [1]. Its purpose is to provide protection for newborns as much as possible, relieve parents of worries, and let children grow up happily and healthily.

Moreover, the vaccines in this immunization program are free for all children of appropriate age. If we calculate the huge base of births in our country each year, multiply it by the more than 20 doses of vaccination a child needs before the age of 6, as well as the additional public medical basic resources and human resources investment, it is enough to see how deeply our country loves children.

At present, in addition to the welfare immunization program vaccines (Class I vaccines) provided by the state, there are many excellent non-immunization program vaccines (Class II vaccines) on the market, that is, self-funded vaccines. Together with the immunization program vaccines, they further consolidate the immune protection shield and provide children with more comprehensive protection.

02. When is the best time to get vaccinated?

Now that we have vaccines, the next question is when should we vaccinate our children? my country's immunization schedule and vaccine instructions will indicate the vaccination time for children. Experts often say that we should "vaccinate in time and as early as possible", but there are always parents who "accidentally" delay the vaccination time. There are many reasons for this, some because it is inconvenient to take leave, some because the child happens to be sick, and sometimes they simply forget, and ultimately fail to vaccinate their children in time.

Some people may say that a few days of delay is no big deal, but if an epidemic happens to break out, children who lack vaccine protection will be in trouble. If they are accidentally infected with the disease, various treatments will follow, which will not only make the children suffer, but also the parents will suffer.

Therefore, during the growth of children, we must pay special attention to vaccination and immunization, and we must go a step further and not only vaccinate them, but also vaccinate them "in a timely and early manner."

03. About human immunity

Our body's immunity is divided into innate immunity and acquired immunity. The former, as the name suggests, is innate immunity, including the tissue barrier formed by our skin and mucous membranes, as well as innate immune cells and innate immune molecules. These are possessed by everyone, but they are not specific to a certain antigen, so they are called nonspecific immunity. In layman's terms, it can be understood as using the same weapon to defend against different antigens.

The familiar immunity such as antibodies is called acquired immunity, which develops after we are born and works specifically against specific antigens, so it is also called specific immunity. Since acquired immunity is more targeted and specific, the speed and effect of immunity are naturally better.

But here comes the problem. Acquired immunity begins to be gradually established after birth, and babies have to face this complex world full of various microorganisms from the moment they are born. What should they do?

Some people may say that breast milk also contains certain immune substances. This is true! These immune substances can protect the baby when it is born. Their existence allows the newborn to get rid of the hard mode of survival.

However, these immune systems are not long-lasting. Over time, the immune substances in breast milk will also decline rapidly. This is supported by research. The figure below shows the test data of active substances in breast milk. We can see that over time, both antibodies such as IgM and active substances such as lactoferrin gradually decline, which means that the protection for the baby is also declining [2].

04. What is the principle of vaccine?

Vaccines can be said to be one of the greatest inventions of mankind in dealing with this risky world. Since Dr. Jenner first used cowpox to save smallpox hundreds of years ago, mankind has invented hundreds of vaccines.

The principle of vaccines is to provide early immunization. Through specially made low-toxic or even non-toxic vaccines, our bodies can build up specific immunity in advance. In this way, when real pathogens invade, the body's specific immunity will quickly resume production and provide protection.

Especially for babies with weak immunity, they need the support of vaccines to fight against very serious infectious diseases, such as whooping cough, tetanus, diphtheria and other diseases that are very easy to infect babies, to help them establish an immune defense line in advance.

It can be seen from this that from the perspective of coping with diseases and enhancing resistance to infectious diseases, immunization should be carried out as early as possible, especially for infants and young children, whose immunity is so fragile. If they are vaccinated as early as possible, they can establish the ability to fight diseases as early as possible and allow the baby to survive better.

05. Is it better to get the vaccine as early as possible?

So, does it mean that all vaccines should be given as early as possible? Definitely not.

This is because the safety and preventive properties of each vaccine are different, so you must refer to the product instructions for vaccination. Today we will talk about the diphtheria, pertussis and tetanus vaccine that infants and young children must receive as an example.

The DTP vaccine is a vaccine that protects against pertussis, diphtheria, and tetanus. Each of these three infectious diseases has been notorious in history and has caused serious infectious disease outbreaks [3].

Currently, there are three types of vaccine products that contain DTP: DTP vaccine [4], quadrivalent vaccine [5], and pentavalent vaccine [6]. If you read the instructions for these three products, you will find that their first immunization time is different. DTP vaccine and quadrivalent vaccine are injected at the earliest 3 months, while pentavalent vaccine can be injected one month earlier, at 2 months. Don't underestimate this one month earlier. For newborn babies, the earlier they are immunized, the earlier they can prevent the occurrence of the three diseases. Especially pertussis, which is a common infectious disease in young children. This one month difference may save many babies from suffering from illness.

So, the second question arises: why do vaccine products that prevent the same disease have different vaccination times?

This is mainly because the clinical trial procedures for different vaccines are different. A complete vaccine cycle includes preclinical research and clinical trials. During the clinical trial stage, multiple indicators of the subjects need to be screened as a guide for future applications. Among them, the age of the subjects is an important factor. But we also know that the younger the baby, the more fragile they are, and the potential risks of clinical trials are higher [7]. Therefore, vaccine manufacturers will fully evaluate the safety of their products for young children. After evaluation, some vaccine manufacturers chose 2-month-old infants for clinical trials, while some vaccine manufacturers chose 3-month-old children for clinical trials after evaluating the safety of their own products. This also explains the problem of different vaccination times for vaccine products that prevent the same disease.

Although the earlier infants are immunized, the better, as we mentioned earlier, the younger the infants, the more vulnerable they are, which puts higher demands on the vaccine preparation process and safety. For example, the pentavalent vaccine that can be administered at 2 months of age uses a more advanced component purification process, which can make the vaccine components purer and reduce the endotoxin content, thereby ensuring early vaccination and reducing the incidence of adverse reactions to the vaccine.

Of course, apart from the difference in vaccination time, any vaccine, as long as it is approved by the state, is safe and effective. In fact, it is precisely because of the popularization of vaccines that the incidence of various infectious diseases in newborns has been greatly reduced [8][9][10]. It can be said that the invention of vaccines is a major milestone in human development. For the first time, we have taken the initiative in the fight against diseases, and have achieved early prevention from the unpredictable.

Finally, I want to say that many parents spend a lot of time taking care of their babies, but ignore their babies' vaccinations, which I think is very undesirable. So I hope more parents can realize the importance of vaccines and take their children to get vaccinated in a timely and early manner.

[1] National Immunization Program Vaccine Childhood Immunization Schedule and Instructions (2021 Edition)[J]. Chinese Journal of Diseases, 2021, 11(04): 241-245.

[2] Ren, Qiqi, et al. "Longitudinal changes in the bioactive proteins in human milk of the Chinese population: A systematic review." Food Science & Nutrition 9.1 (2021): 25-35.

[3] Vardell, E. (2020). Global health observatory data repository. Medical Reference Services Quarterly, 39(1), 67-74.

[4] Instructions for use of adsorbed acellular diphtheria, tetanus and pertussis combined vaccine. Chengdu Institute of Biological Products Co., Ltd.

[5] Instructions for use of acellular diphtheria, tetanus, pertussis and Haemophilus influenzae type b combined vaccine. Beijing Minhai Biotechnology Co., Ltd.

[6] Instructions for use of adsorbed acellular diphtheria, pertussis, poliomyelitis and Haemophilus influenzae type b combined vaccine. Sanofi Pasteur

[7] Zimmermann, Petra, et al. "Correlation of vaccine responses." Frontiers in Immunology 12 (2021): 646677.

[8] WHO. Pertussis vaccines: World Health Organization position paper ‒ August 2015. Available at: https://www.who.int/publications/i/item/WER9035

[9] WHO. Pertussis vaccines: World Health Organization position paper ‒ August 2015. Available at: https://www.who.int/publications/i/item/WER9035

[10] WHO. Tetanus vaccines: World Health Organization position paper ‒ February 2017. Available at: https://www.who.int/publications/i/item/WER9206