Second Dose of Chickenpox Vaccine Updated: Why Is It Necessary?

Updates to the vaccination schedule and question marks in parents' minds continue to be at the top of the child health agenda. The Ministry of Health's addition of the second dose of the chickenpox vaccine to the routine calendar of the 48th month (4 years old) as of September 2026 and the launch of catch-up vaccination for children between 49-72 months aroused widespread interest among families. This decision, which comes after the vaccine has been administered as a single dose every 12 months in Türkiye since 2013, asks "Is an additional dose really necessary?", "Does the vaccine have any side effects?" and "What should be done in case of a previous illness?" It also brought with it questions.

REASONS BEHIND THE SECOND DOSE DECISION

Child Health and Diseases Specialist Prof. stated that he found this decision taken by the Ministry of Health very appropriate and correct. Dr. Yakup Çağ said that there is no significant change in the increase in cases compared to previous years, and although even a single dose of vaccine has a high protection rate of 82-85%, there may be small-scale increase in cases in schools and nurseries from time to time.

Prof. Dr. Yakup Çağ added:

"This second dose of vaccine will reduce the increase in cases and therefore the number of viruses in circulation. The main reason for administering the second dose is to prevent chickenpox infection and its spread. Giving the vaccine, especially in the preschool period, will make a significant contribution to reducing the number of cases and the spread of the disease in the society."

DECREASING IMMUNITY PICTURE WITH TIME AND THE PROTECTION PROVIDED BY THE ADDITIONAL DOSE

The World Health Organization has long implemented the two-dose protocol in many countries, including the USA and the UK. What kind of a decrease in the immunity level of a child who is medically vaccinated with a single dose occurs over the years, and how exactly does the second dose change this immunity picture?

Saying that the immunity level may decrease slightly, but it is not completely eliminated, Yakup Çağ answered the question as follows:

"Protection, which is 95-97% one year after vaccination, drops to 86% in the second year, and becomes around 81-86% in the following years. Studies have reported that antibodies continue even 7-10 years after one dose of vaccine. The second dose brings the vaccine protection rate to around 98-100%."

SAFETY PROFILE OF THE VACCINE AND POSSIBLE MILD SIDE EFFECTS

Family physicians follow childhood vaccinations very closely. Parents of children over the age of four have begun to be called for an additional dose of chickenpox vaccine. Many parents who were informed about the vaccine said, "He had already been vaccinated at the age of one. Is this additional dose necessary? Will it have any side effects?" has concerns.

Prof. Dr. Yakup Çağ said that parents should not worry about this issue and that it is extremely safe to give the second dose at the age of 4-6 for children who were previously vaccinated against chickenpox at the 12th month.

Yakup Çağ, who underlined that although the second dose application has just started to be implemented in our country, has been used in some countries for years and is generally safe, also touched upon the possible side effects:

"Of course, there may be mild side effects such as pain, swelling and redness at the vaccination site, fever, weakness, restlessness, and a chickenpox-like rash. Very, very rarely, serious side effects such as allergies, seizures and central nervous system effects may occur."

APPROACH IN CHILDREN WHO HAVE NATURALLY TRANSMITTED THE DISEASE OR ARE SUSPECTIVE

Should the second dose be given to children in the 4-6 age group who received their first dose of vaccine at the 12th month, but who have recovered from chickenpox 'naturally' in the intervening years or are suspected of having had it? Is there a medical risk in giving a second dose to a child who has accidentally or unknowingly contracted the disease?

Yakup Çağ gave the information: "First of all, even if the chickenpox vaccine is given to children who were vaccinated at the 12th month and subsequently had chickenpox, it is generally considered safe, that is, there will be no difference in terms of side effects compared to other children. If there is clinical evidence from the laboratory or physician that these children have chickenpox, the second dose may not be necessary because the protective feature of natural immunity is quite high. However, if there is no such evidence, only if there is suspicion, then the vaccine should be given."

VACCINATION RECOMMENDATION FOR CHILDREN 7 YEARS AND OLDER

The Ministry of Health included children between the ages of 49-72 months in catch-up vaccination. However, for example, primary school children who are 7 or 8 years old and have received a single dose of vaccine on time are currently excluded from this free schedule. Do children in this age group need additional vaccination?

Prof. Dr. Çağ stated that if children over the age of 7 were vaccinated against chickenpox at the 12th month and had a chickenpox infection during this period and this was medically proven, they do not need to be vaccinated again.

Underlining that otherwise they should be vaccinated, Yakup Çağ gave the following information:

“Since children aged 7 and above are not in the ministry's vaccination program, families can get it and have it administered for a fee.”

ADULTHOOD PROTECTION AND RISK OF SHINGLES

Prof. Dr. Yakup Çağ said that one of the important purposes of giving the second dose of vaccination is not only to protect the child, but also to protect individuals who are not vaccinated and at risk of severe disease by reducing the circulation of the chickenpox virus in the society. Çağ added that it is predicted that it will naturally reduce disabilities and deaths due to chickenpox in older ages, and also indirectly reduce shingles disease.

'THE RISK CONTINUES EVEN ONE YEAR LATER'

A striking example showing that chickenpox should not be seen as just a rash and mild disease occurred in Scotland.

The paralysis of a 4-year-old child named Olivia Elliot, six months after her chickenpox infection, has brought to the fore the hidden dangers of childhood diseases that seem innocent, as we are talking about the second dose of chickenpox vaccine. Starting with complaints of vomiting and headache, the little girl developed loss of movement and speech on her left side. In the examinations, it was understood that the chickenpox virus triggered paralysis by causing inflammation in the vessels feeding the brain.

Making a statement, Child Neurology Specialist Prof. Dr. Dilara Füsun İçağasıoğlu stated that Varicella-Zoster virus (chickenpox) can cause narrowing and blockage in the brain vessels. İçağasıoğlu; He warned that this type of stroke risk may occur within the first year after contracting the virus (early period) or may develop over a year (late period).

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