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On 28.02.2023 another edition of the Vaccine School initiative was held, which is created in partnership with the Ministry of Health, Astra Forum Foundation and UNICEF with the hosting of the CredoWeb platform for specialized information for medical professionals.

The main focus of the webinar was the topic of “Implementation of the immunization calendar in 2022”. Momchil Baev, founder and chairman of Astra Forum Foundation, opened the meeting and introduced the speakers: Dr. Kremena Parmakova from the Ministry of Health, Executive Director of the Executive Drug Agency pharmacist Bogdan Kirilov, epidemiologist of infectious diseases for University Multidisciplinary Hospital for Active Treatment St. Georgi (UMHAT St. George) Ltd. – Dr. Hristiana Batselova.

At the event, Dr. Parmakova presented data on the implementation of the immunization calendar for 2022. The data that stood out was about reimmunization – a pressing but not so widely discussed topic, according to Dr. Parmakova. The requirements of the World Health Organization to achieve containment, elimination or eradication of infectious diseases, is to achieve 95% immunization coverage. The minimum global targets set by the WHO are 90% national and 80% regional coverage of mandatory immunizations against diseases such as measles, poliomyelitis, diphtheria, tetanus, pertussis (whooping cough), parotitis and rubella.

In 2022, Bulgaria reported 91.4% immunization coverage with a third dose of diphtheria, tetanus, pertussis vaccine and 91.2% with a first dose of measles, parotitis and rubella vaccine.

The reported immunization coverage with a second dose of measles, parotitis and rubella vaccine in Bulgaria is 82.20%. Over the period 2012 to 2022, the results for immunization coverage for the various mandatory immunizations show that it is predominantly below 95%. The only vaccine that has maintained stable levels is the tuberculosis vaccine – 95%. On the opposite side is the second dose intake of measles, parotitis and rubella vaccines (among 12-year-olds), with coverage ranging between 84.5% (in 2020) and 94% (2012). Considering the observed tendencies, Dr. Parmakova finds it encouraging that in 2022 there was an increase in mandatory immunization coverage over 90%.


Immunization coverage over the 2014-2022 period with reimmunizations in children and adults ranges widely: from 24.4% against tetanus and diphtheria in people at the age of 85 years and older in 2020 to 91.8% in 2017 with a fourth dose of pneumococcal vaccine. Only about half of the adult population, subject to tetanus and diphtheria immunization is immunized each year, and during the pandemic, these numbers decreased.

Dr. Parmakova also provided data on the reasons for the low rates, and also added – “most refusals of re-immunization report “other” as the reasons (reaching levels of 15.54% for diphtheria, tetanus and pertussis in 12-year-olds)”. This leaves more room for speculation and causes confusion about the real reasons why people do not get the mandatory vaccines. Those who gave the reason “refusal” were only a few single cases, while medical reasons ranged between 2% and 3%. Among adults, between 45% and 53% are people who are not immunized because of other reasons.

Dr. Parmakova also suggested ways to improve vaccine insertion reports. She reminded that vaccines administered in childhood are compatible. This means that they do not need to be delayed in time and given over a short period of time, but can be given simultaneously. This also reduces the stress for the child by limiting immunizations to a short period of time instead of several consecutive time periods. Dr. Parmakova also gave an example of a case where it is mandatory to have a 30-day interval between vaccines: when administering BCG (Tuberculosis) vaccine separately from other live vaccines.

Also, if immunizations are missed in some individuals, priority is given to immunizations over reimmunizations, and it is possible to give immunizations and re-immunizations on the same day.

Dr. Parmakova paid special attention to the correct appliance of the vaccines, because their incorrect administration leads to an increase in local side reactions as well as a decrease in trust among parents, an increase in vaccine intervals, lack of implementation of the immunization calendar and possible future refusal of re-immunization.

It was also noted that there could be possible statistical errors in the reporting of people subject to and covered by the immunization calendar of the Republic of Bulgaria. Dr. Parmakova pointed out several examples of discrepancy in the numbers between people immunized at the same age but with different numbers of the different types of vaccines.

The specialist concluded her presentation with an appeal – all workers from different institutions and organizations to work together as a team.


Bogdan Kirilov, the next speaker at the webinar, revealed the adverse drug reactions that have been reported after vaccination against COVID-19 for the period December 2020 to March 2022. Their number is 4068 and Mr. Kirilov clarified that in Bulgaria the registered complaints are statistically distributed at the ratio of 1000:1. This means that for every 1000 vaccinations, there is 1 registered adverse reaction.

Bogdan Kirillov presented the audience with the data on the registered adverse reactions to the different vaccines against COVID-19 in relation to other immunizations. There was a significant peak between February 2021 and July 2021 in complaints about the AstraZeneca (Vaxzevria) vaccine. This led to the European Medicines Agency to temporarily suspend its use in March 2021 in order to conduct further research. When the vaccine’s status was reinstated, however, complaints continued at a high rate. According to Mr Kirilov, people’s concerns about this vaccine have not been successfully relieved and therefore there was a decrease in number of people, who wish to be vaccinated with it. It can be concluded that the more a vaccine is applied, the numbers of reported side effects increases.

Bogdan Kirilov revealed that most of the complaints about vaccines are precisely those that have been described on the product itself. There has also been a worrying increase in patient complaints about adverse drug reactions. For comparison, in 2020 the number was 601 and in 2021 the figure had increased to 4114. In a percentage ratio with the adverse reaction reports, submitted by medical professionals in 2021, this equates to 87.40% to 12.60% in favor of patients. This means that a lot more people are expressing an opinion about something they have no expertise in. On a positive note, Mr. Kirilov pointed out that the tendency for 2022 appears to be back to the normal (or percentage-aligned) ratio that was seen before 2019 between patients and doctors.


Dr. Hristiana Batselova was the other speaker at the webinar series “Vaccine School”. She introduced us to case studies that doctors often encounter in their practice. The first case she presented was regarding a child who had typical varicella symptoms. The child most likely contracted it at the educational institution he attends, as there is an outbreak of the disease there. The young mother was in contact with her child and had no recollection of having had chickenpox (varicella). She purchased Varivax and stored it in a refrigerator – according to the rules for storing bioproducts. The woman’s GP refused to administer the vaccine because he wanted proof that the woman had not had varicella in the past. He recommended the woman to get tested for serum IgG. The young mother has her examination, but meanwhile, 8 days pass have passed since contact. Eventually the test shows that the mother has not been through the disease and the GP agrees to give her the vaccine.

In this case, Dr. Batselova pointed out that it was not necessary to do these tests because even if the person in question had chickenpox and had immunity, giving a live chickenpox vaccine does not endanger their health in any way. The important thing in this case was to act quickly with the vaccine (third to fifth day since contact). After the vaccine was administered on the eighth day, the woman eventually developed symptoms of chickenpox on the 15th day.

The next case that Dr. Batselova introduced us to was also related to chickenpox. A child, who was in contact with other children in kindergarten, came home where the family had a baby. The baby has not yet been given the chickenpox vaccine. The mother in this case asked whether she should give the vaccine or wait 2 weeks. In this case, there is no reason to delay administering the varicella vaccine to the baby because the baby is not in contact with a varicella patient.

Dr. Hristiana Batselova also introduced us to a case in which a young woman wanted to know if there was a necessary interval between vaccination against chickenpox and possible pregnancy. Dr. Batselova stated that it is advisable to wait 30 days after the varicella vaccine before initiating a planned pregnancy. However, she also pointed to cases in which unplanned pregnancies occur simultaneously alongside vaccination. Batselova added that there is nothing worrying about this.

A 39-year-old woman with a first dose of Varivax who needed a second dose but was refused by two different medical centres – this is the other case presented by Dr. Batselova. The explanation given by the medical establishments was that there were currently many cases of varicella and the vaccine in question should not be given. Dr. Batselova explained that there is no valid medical explanation for not administering the vaccine against chickenpox or any infectious disease, during a disease outbreak.

Could the combined Twinrix vaccine against viral hepatitis A and B be given – “a frequently asked question by parents” said Dr. Batselova. The reason for this question is that there has been a lack of importation of the monovalent hepatitis A vaccine in Bulgaria for some time and most people are vaccinated against viral hepatitis B. The specialist clarified that there is no medical risk, and it can be applied in a 3-dose regimen.

Dr. Hristiana Batselova made an important clarification about viral hepatitis B. The recombinant vaccine against the virus builds a good immune memory and routine re-immunization of the population is not necessary. If there is a higher risk of infection with the virus, testing is performed and if there is no protective titre, a new dose of the vaccine is administered. The test is repeated after 30 days. If a protective titre is present, no more doses are given, but if there is still a lack of a protective titre, 2 more doses are given as per the vaccine schedule.

One of the most common questions asked about HPV, Dr. Batselova pointed out, is whether there is a need for any testing, prior to vaccination against the disease. She explained that this is not necessary, even if the person is already infected with some types of HPV.

In the presence of a permanent sexual partner, the HPV vaccine is necessary, Batselova added. According to her, there is no need for an interval between HPV vaccination and getting pregnant.

In her words, the vaccine is most effective when administered between the ages of 9 and 17, but research has shown that it can also be effective when given to people up to the age of 45.

After the speakers’ presentations, there was opportunity for questions and discussion. Among the first questions was the one about vaccines and their timely application in case of already existing contact with COVID-19 infection. Dr. Parmakova and Dr. Batselova agreed that in case of a short incubation period, the vaccine cannot have a protective effect, since the infection has already spread in the body.

There was also a question addressed to Dr. Batselova and the data she provided on the HPV vaccine. Since its effectiveness is directly correlated with the average age of beginning sexual activity, Dr. Batselova indicated that for people over the age of 13, the effectiveness of the HPV vaccine decreases as the number of people who have become sexually active increases. This means that they have had an encounter with one of the HPV types. According to the epidemiologist, everyone has been infected at least once in their lifetime.

The growth of varicella cases was a topic raised by webinar participants. Dr. Batselova pointed out that the disease has a cyclical pattern that is usually associated with the winter months and the spread usually occurs when there is a large concentration of children in schools, kindergartens and nurseries. In the outbreak of the COVID-19 epidemic and the restrictions and lockdown that followed, these children were unable to come into contact with their peers. With the return of most of them to educational institutions, there is a natural new outbreak of the disease. With an immunization coverage of at least 80% against varicella, this cycle will be prevented, concluded Dr. Bacelova. Dr. Parmakova added that chickenpox is a vaccine-preventable disease, and while there are doctors and parents, who are not convinced of this and surrender to worries and doubts in science, things are left up to chance.


She appealed for more efforts to be made from the medical professional community.

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