Vaccination against Haemophilus influenzae type B infections reduced in the United Kingdom
Two studies by scientists in the United Kingdom have shown an increase in the frequency of infections caused by Haemophilus influenzae type B, associated with a decrease in the effectiveness of vaccination.
In a retrospective study by scientists from the United Kingdom, it was shown that an increase in the frequency of infections caused by Haemophilus influenzae type B (Hib) coincides with the introduction in 1999 of the practice of the Hib vaccine combined with pertussis-diphtheria tetanus vaccine.
The study compared the type of Hib vaccination in 129 children who had a full course of vaccination and who had Hib infections with children of the same age in the control group who also received a full course of vaccination and who were not sick.
After performing a logistic regression analysis, it was found that patients in the main group were more likely to receive the 3 doses of Hib vaccine associated with the pertussis-diphtheria-tetanus vaccine. A tendency to fail vaccination has also been identified with each additional dose of the combination vaccine. In addition, the researchers noted a less effective vaccination in patients who received 2 or 3 doses of the Hib vaccine combined with the pertussis-diphtheria-tetanus vaccine compared to patients who received 3 doses of the Hib mono-vaccine.
Scientists note that their study confirms the importance of long-term disease population control for prevention of vaccination, especially in cases where changes are made to the standard vaccination schedule.
Another study, also conducted in the UK, showed a change in the level of immunity to H. influenzae type B infections in children before and after the introduction of standard vaccination against Hib in health care practice in 1992.
The study analyzed 2,610 serum samples from children aged 1 to 15 for 1990-1991, 1994, 1997 and 2000. After the introduction of standard Hib vaccination, the number of children under 5 years with protective antibodies increased significantly in 1994, which corresponded to a marked decrease in the frequency of infections caused by Haemophilus influenzae type B. Study of the samples obtained in 1997 and 2000, he It was found that the average level of antibodies against H. influenzae type B in children 3 to 4 years of age was then lower than that of children in the same age group in 1994, when the most children have been vaccinated during an active vaccination program. Levels of antibodies to H. influenzae type B decreased slightly over the period 1994 to 2000.
The second comprehensive immunization program for children aged 6 months to 4 years started in the United Kingdom in April 2003. It is expected that the introduction of the program in a short period of time will increase immunity and reduce the incidence of the disease.
According to the researchers, consideration should be given to revising the vaccination rules, including the introduction of an additional booster dose of the vaccine and the modification of the standard vaccination schedule for children in their first year of life.