Pertussis vaccination

Whooping cough in children of the first months of life is especially severe - with attacks of apnea, pneumonia, atelectasis (25%), convulsions (3%), encephalopathy (1%). Vaccination against whooping cough, carried out in children with coverage of more than 95% in Russia led to a decrease in the incidence from 19.06 per 100,000 population and 91.46 per 100,000 children under 14 years in 1998 to 3.24 and 18.86 in 2005 and 5.66 to 34.86 in 2007, respectively.

However, whooping cough in older children and adolescents, although often not diagnosed, constitutes a significant part of the morbidity. In 2006 in Russia, out of 7681 cases of whooping cough in children aged 0-14 years (35.83:100,000), 1170 cases were in children under 1 year (79.8:100,000), 878 at the age of 1-2 years (30.42:100,000), 1881 at 3-6 years (36.64:100,000) and 2742 at 7-14 years (72.8:100,000), i.e., 1/3 of all registered cases occur in schoolchildren.

Whooping cough incidence in some countries per 100,000 population

England - 0.5	Spain - 0.7	Austria 1.8
Iceland - 3.6	Malta - 3.7	Ireland -4.5
Italy - 6.1	Germany 10.1	Sweden - 22.3
Holland - 32.7	Norway -57.1	Switzerland -124
USA - 2.7	Canada - 30.0	Australia - 22-58

In 1998-2002 in a number of countries its maximum occurred in children under 1 year of age (Denmark 253.1 per 100,000, Switzerland - 1039.9, Norway - 172.5, Iceland - 155.3). The greatest increase occurs in the age group over 14 years, the average age of people falling ill with whooping cough in Europe increased from 7 years in 1998 to 11 years in 2002 due to a decrease in the proportion of people falling ill at the age of 5-9 years (from 36% in 1998 to 23% in 2002) with an increase in the proportion of people over 14 years (from 16% to 35%). In the USA in 2005, 30% of all cases of whooping cough were registered in the group of people 21 years and older.

The true incidence of whooping cough is much higher than the registered one: a significant part of illnesses of children and teenagers, accompanied by a long-term (more than 2 weeks) cough, are caused by whooping cough. Both partially vaccinated and correctly vaccinated children get sick, and it is obvious that immunity begins to weaken from the age of 5. According to new estimates, 600,000 adults in the USA get whooping cough every year - with a cough lasting 2-4 months and repeated visits to the doctor.

Patients with a long cough provide active circulation of the pathogen, 90-100% of susceptible individuals who were in close family contact with the patient become ill with whooping cough, the relative role of adolescents and adults as sources of infection has increased. For children, especially those aged 1 year; adolescents, according to the literature, most often become infected at school (39%), from friends (39%), family members (9%), and adults - from colleagues (42%), in the family (32%), from friends (14%).

The existing scheme of whooping cough vaccination (3-time vaccination and 1 revaccination) creates a high level of immunity, which decreases by school age. This is what prompted many countries to conduct the 2nd revaccination at 5-11 years (Belgium, France, Germany, Spain, Portugal, USA, Japan, etc.), and Austria, Finland and Switzerland - also the 3rd revaccination at 11-15 years. In England, only 1 revaccination is carried out - but at 3 years, in New Zealand - at 4 years, and in Denmark - at 5 years.

For revaccination, all countries except Brazil use acellular vaccine against whooping cough. It is obvious that in Russia, too, a second revaccination is necessary.

When conducting the 2nd revaccination before the age of 6 years, it is possible to use the acellular vaccine AaDDS, but at an older age, a reduced dose of diphtheria toxoid should be administered. Such vaccines (AaDDS) have been created, but are not registered in Russia: Boostrix (GlaxoSmithKline) for the age of 11-18 years and Ldasel (Sanofi Pasteur). They are also administered at a period from the previous dose of ADS (ADS-M) to 5 years.

Pertussis vaccines registered in Russia

Anatoxin	Contents, preservative
DPT - whole cell pertussis-diphtheria-tetanus vaccine - Microgen, Russia	In 1 dose (0.5 ml) >30 IU diphtheria, >60 IU tetanus toxoids, pertussis vaccine >4 IU. Aluminum hydroxide, preservative thimerosal
Infanrix (AaDTP) - diphtheria-tetanus three-component acellular pertussis vaccine, GlaxoSmithKline, England	In 1 dose >30 ME diphtheria, >40 ME tetanus, 25 mcg pertussis toxoid and filamentous hemagglutinin, 8 mcg pertactin. Aluminum hydroxide 0.5 mg. Preservatives - 2-phenoxyethanol, formaldehyde up to 0.1 mg
Pentaxim (AaDTP+IPV+HIB) - diphtheria-tetanus-acellular pertussis-polio and Hib vaccine, sanofi pasteur, France	In 1 dose >30 IU diphtheria, >40 IU tetanus, 25 mcg pertussis toxoids, 25 mcg FHA, 10 mcg Hib polysaccharide, D antigen of polioviruses: type 1 (40 units), type 2 (8 units) and type 3 (32 units). Aluminum hydroxide 0.3 mg. Preservatives 2-phenoxyethanol (2.5 μl). formaldehyde (12.5 mcg).
Tetraxim (AaDTP + IPV) - diphtheria-tetanus-acellular pertussis-polio vaccine, sanofi pasteur, France (submitted for registration)
Infanrix-penta (DTP+IPV+HeaV) - diphtheria-tetanus-acellular pertussis-polio and Hib vaccine, GlaxoSmithKline, Belgium (submitted for registration)
Infanrix-hexa (DTP+Hib+IPV+HepB) - diphtheria-tetanus-acellular pertussis-polio, Hib and hepatitis B vaccine, GlaxoSmithKline, Belgium (submitted for registration)

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The purpose of whooping cough vaccination

The whooping cough vaccine prevents over 35 million cases of the disease and over 600,000 deaths worldwide each year. However, the WHO target for Europe to reduce the incidence of whooping cough to less than 1 per 100,000 population by 2010 is unlikely to be achieved without the introduction of a second revaccination. Maintaining a high level of coverage among young children is also important; its decline led to an increase in the incidence of the disease in Russia in the 1990s. In England, a decline in coverage from 77% in 1974 to 30% in 1978 led to a whooping cough epidemic with 102,500 cases. In Japan in 1979, 4 years after vaccinations were stopped (due to attacks on the whole-cell vaccine), 13,105 cases with 41 deaths were registered.

Post-exposure prophylaxis of pertussis

For emergency prevention of whooping cough in unvaccinated children, normal human immunoglobulin can be used - twice with an interval of 24 hours in a single dose of 3 ml as soon as possible after contact with the patient. More effective is chemoprophylaxis with a macrolide in age-appropriate doses for 14 days (azithromycin - 5 days); in newborns, 16-membered macrolides (Vilprafen Solutab, Macropen, Spiramycin) should be used, since 14- and 15-membered ones can cause pyloric stenosis in them.

Vaccination against whooping cough is not administered to unvaccinated children in contact; vaccination of partially vaccinated children continues according to the calendar. If a child received the 3rd dose of DPT more than 6 months ago, it is advisable to perform revaccination.

Vaccinations against whooping cough

Whole-cell vaccines, containing all components of the microbial cell, are recommended by WHO as the main means of preventing whooping cough. A number of developed countries use acellular (cell-free) vaccines, which are devoid of bacterial membrane lipopolysaccharides that cause reactions. All vaccines are stored at 2-8°, and are not to be used after freezing. Buba-Kok.

The acellular pertussis-diphtheria-tetanus vaccine Infanrix (AaDPT) is well known to pediatricians; since its registration (2004), more than 1 million doses of the vaccine have been used in Russia. Vaccines of the Infanrix family are registered in 95 countries, with a total of 221 million doses used. It contains three 3 B. pertussis antigens: pertussis toxin, filamentous hemagglutinin and pertactin; its high immunogenicity and low reactogenicity allow increasing vaccination coverage by vaccinating children who have contraindications to whole-cell DPT.

In 2008, the Pentaxim vaccine was registered in Russia. In addition to diphtheria and tetanus toxoids, it contains enhanced IPV, Hib and 2 components of the acellular pertussis vaccine. Pentaxim is registered in 71 countries and is included in the calendar of 15 European countries and a number of countries on other continents. The immunogenicity of this vaccine corresponds to that with separate administration of vaccines; it remains at a good level even at the age of 5 years. For example, in Sweden, in the counties where only the Pentaxim vaccine was used (according to the 3-5-12 months schedule), its effectiveness against whooping cough was 91% after 2 doses and 99% after 3 doses.

All vaccines are administered deep into the outer thigh muscle in a dose of 0.5 ml according to the Calendar - at the age of 3, 4, 6 and 18 months.

Immunity after whooping cough vaccination

A full course of vaccinations against whooping cough with a whole-cell vaccine provides protection, especially against severe forms of whooping cough, to 80% of those vaccinated, against diphtheria and tetanus - more than 95% of those vaccinated. The protective effectiveness of the Infanrix vaccine is comparable, the presence of pertactin in it is important to maintain a high degree of immunity to whooping cough. Immunity to whooping cough with the use of all vaccines decreases after 5-7 years, which justifies the 2nd revaccination.

The comparative immunogenicity of acellular vaccines with different numbers of components has been discussed in the literature. One study comparing studies conducted before 2001 showed that 1-2-component vaccines had an efficacy of 67-70%, while those containing 3 or more components had an efficacy of 80-84%, with the efficacy of whole-cell vaccines being 37-92%. These findings have been criticized because the comparison included an experimental 2-component vaccine that was subsequently withdrawn from production. Several 2-component vaccines analyzed by the authors were subsequently licensed in countries such as Sweden, Japan, and France and have been successfully used since then. In response, the authors acknowledged that the lower immunogenicity of the 2-component vaccines was indeed due to the inclusion of data on the experimental vaccine and that, with its exclusion, there were no differences in immunogenicity depending on the number of components.

A final point in this discussion was made by a recently published article by Vidor E. and Plotkin S.A. Data on 2-component vaccines obtained by 75 research groups in 36 projects in different countries in 1987-2006 showed their high efficiency, including in comparison with whole-cell vaccines. It should be noted that comparisons of the efficiency of vaccines, including those with different numbers of components, are considered invalid by national authorities regulating issues of immunoprophylaxis, since these vaccines have been tested and registered for use in the country. At the same time, the main trend in increasing the efficiency of pertussis vaccines is the development of preparations with 3-5 components.

Contraindications and vaccinations against whooping cough for children with chronic diseases

Severe reactions and complications, known hypersensitivity to any component of the vaccine or hypersensitivity to a previous dose of this vaccine are contraindications to the administration of the same pertussis vaccine. Progressive diseases of the central nervous system are a contraindication for DPT and Pentaxim vaccine, a history of afebrile seizures - for DPT. For the Infanrix vaccine, a contraindication is encephalopathy that has developed within 7 days after the previous administration of this vaccine.

In case of a strong reaction or complication to the whole-cell pertussis vaccine, vaccinations may be continued with acellular vaccines or toxoids. If the child has a strong reaction to the 1st administration of DPT, in the absence of acellular vaccine, the course of vaccination against diphtheria and tetanus is continued with ADS, which is administered once, no earlier than 3 months later; after the 2nd dose of DPT, the course of vaccinations against diphtheria and tetanus is considered complete, in both cases the first revaccination is carried out with ADS 12 months after the last vaccination. After the third vaccination with DPT, revaccination is carried out with ADS 12-18 months later.

Children with less pronounced CNS pathology, if there are concerns regarding the introduction of DPT, are preferably vaccinated with vaccines with an acellular pertussis component. Prematurity, stable allergic manifestations (localized skin, latent or moderate bronchospasm, etc.) are not contraindications to vaccination, which can be carried out against the background of appropriate therapy. For children with febrile seizures, the pertussis vaccination is carried out against the background of antipyretics.

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Reactogenicity of the whooping cough vaccine

After vaccination against whooping cough, a child may develop fever (with febrile seizures in susceptible children), malaise, soreness, hyperemia and swelling at the injection site are common. Prescribing paracetamol 2-3 hours after vaccination and the following day prevents a sharp increase in temperature and seizures.

The reactogenicity of Infanrix in terms of temperature, local pain and redness, as well as irritability, drowsiness and decreased appetite is lower than that of whole-cell vaccines, which allows it to be used in children with health problems.

In rare cases, allergic reactions ( Quincke's edema, urticaria, polymorphic rash) may develop, mainly to repeated doses of DTP, more often in children who had similar reactions to previous doses; it is advisable to prescribe antihistamines prophylactically to such children. However, the opinion about the "allergenic" effect of DTP is not supported by studies conducted by different methods: vaccination did not increase the incidence of asthma or eczema. Moreover, there is data on the protective effect of the whole-cell pertussis vaccine on the incidence of asthma and, to a lesser extent, eczema.

A piercing scream (squeal) for 1-3 or more hours after vaccination was previously associated with increased intracranial pressure; now the prevailing opinion is that this is the result of a painful reaction to the injection, which leaves no consequences.

Excessively strong general reactions include hyperthermia (40° and above), for local reactions - dense infiltrates more than 8 cm in diameter, sharp hyperemia of the skin with swelling of soft tissues at the injection site (sometimes the entire buttock with transition to the thigh and lower back). Such reactions have been rarely recorded in recent years.

Complications after whooping cough vaccination

All-Russian registration data refute the opinion about the high frequency of complications with DPT: over 6 years (1998-2003) only 85 reports of side effects of DPT were filed, of which only 60 were confirmed. There have been no fatal cases after DPT over the past 10 years.

Anaphylactic shock develops within a few minutes after vaccination, less oftenafter 3-4 hours. In children of the first year of life, the equivalent of anaphylactic shock is a colaptoid state: severe pallor, lethargy, adynamia, a drop in blood pressure, less often cyanosis, cold sweat, loss of consciousness. Bronchial obstruction, croup after the introduction of DPT, are usually caused by acute respiratory viral infections.

Afebrile seizures with loss of consciousness, sometimes in the form of "pecks", absences, gaze arrest are observed with a frequency of 1:30-40 thousand vaccinations and are often incorrectly designated as an encephalic reaction. Usually this is the first manifestation of epilepsy, but it is difficult to deny its connection with the vaccination as a trigger.

Encephalopathy (encephalic reaction) is characterized not only by the presence of seizures, but also by a disturbance of consciousness and/or behavior for more than 6 hours, as well as the appearance of slow waves on the EEG. It is observed much less frequently than isolated afebrile seizures, its prognosis is favorable.

Encephalitis in the post-vaccination period is extremely rare (1:250-500 thousand doses of vaccine), usually we are talking about the disease in the first few days after vaccination, occurring with hyperthermia, vomiting, convulsions, loss of consciousness, hyperkinesis, development of automatisms, paresis, other focal symptoms, usually with severe residual effects. Now these cases are deciphered as CNS diseases not related to vaccination (infectious meningoencephalitis, hereditary leukodystrophy, etc.), the initial manifestations of which coincided with it in time. Of the 4 reports of encephalitis after DPT in 1997-2002, there were 3 cases of viral encephalitis, 1 case of pneumonia with cerebral edema.

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