According to Doctor of Clinical Specialty Level I Danh Thi My Hong, Medical Manager at VNVC Vaccination System, children typically receive initial vaccine doses for diphtheria, pertussis, tetanus, and polio from infancy. However, the immunity generated after these early life vaccinations does not last indefinitely. As children enter preschool age, antibody levels can decline, creating an immunity gap if booster shots are not administered.

This is a stage where many families become complacent. After completing the basic vaccination series during the first one to two years of life, children visit vaccination centers less frequently. Some parents believe their child is "fully vaccinated" or only remember the early childhood vaccine schedule without tracking booster dates. When children attend kindergarten, busy schedules with activities and learning can also lead to missed booster shots.

At preschool age, 4-6 years old, children begin school, interacting with more people and exploring larger environments, thus requiring early disease prevention. Photo illustration: Vecteezy

Doctor Hong states that forgetting a booster shot can reduce a child's protection against diseases such as diphtheria, pertussis, tetanus, and polio. Diphtheria and pertussis, in particular, are transmitted via the respiratory tract and can easily spread in crowded environments like classrooms, daycare centers, and play areas. If there is a source of infection in the classroom, children without full immunity face a higher risk of contracting the disease.

Pertussis can cause severe, prolonged coughing fits, a whooping sound when breathing, cyanosis, vomiting after coughing, and even apnea, pneumonia, encephalitis, and death, especially in young children or those who have not received all recommended doses. Diphtheria can form a pseudomembrane in the throat, leading to breathing difficulties, airway obstruction, myocarditis, paralysis, and a risk of death if not treated promptly.

For tetanus, children aged 4-6 are often active, enjoy running, jumping, and exploring, making them prone to scratches and scrapes during outdoor play. Tetanus bacteria can enter through open wounds, especially those contaminated with soil, dirt, foreign objects, or improperly managed. The disease can cause muscle rigidity, seizures, laryngospasm, respiratory failure, and is life-threatening.

A 7-year-old girl from Tuyen Quang suffered from tetanus, causing full-body stiffness, convulsions, cyanotic lips, and respiratory failure because she had not been vaccinated against the disease, treated at the National Hospital for Tropical Diseases in May. Photo: National Hospital for Tropical Diseases

Doctor Hong advises that children aged 4-6 need a booster shot of the 4-in-1 vaccine to simultaneously protect against diphtheria, pertussis, tetanus, and polio. This booster helps reinforce the immunity that may have waned after the initial doses, maintaining protection as children begin to have more social contact.

"The immune response rate after a booster shot can exceed 95%, which increases protection for preschool-aged children and helps reduce sources of infection in the community", Doctor Hong explains.

In addition to vaccination, parents should maintain good hygiene at home, ensure children eat nutritious meals, get enough sleep, wear masks when necessary, and limit contact with individuals showing respiratory symptoms. However, these measures do not replace vaccines, especially for diseases that can progress severely, such as diphtheria, pertussis, and tetanus.

Doctor Hong recommends that parents check their child's vaccination records when they enter senior kindergarten. If unsure whether the child has received booster shots, families can take them to a vaccination center for appropriate schedule consultation, avoiding the omission of this important vaccine dose for children aged 4-6.

Pregnant woman receiving diphtheria, pertussis, and tetanus vaccine at VNVC Vaccination System. Photo: Dieu Thuan

Beyond booster shots for older children, Doctor Hong also recommends vaccination for pregnant women between weeks 27 and 36 with the 3-in-1 vaccine against diphtheria, pertussis, and tetanus. This is because vaccines are only for children aged 6 weeks and older. Newborns require antibodies from their mother to be protected during the first 6 weeks after birth.

In addition to the 4-in-1 vaccine for children aged 4-6, parents should also be aware of subsequent booster milestones for adolescents (9-15 years old) and adults every 10 years with the 3-in-1 vaccine.

Dieu Anh