What is the incidence of Haemophilus influenzae type b (Hib) infections and disease in India after implementing a universal 4-dose vaccination policy?

From the Guidelines

The incidence of Haemophilus influenzae type b (Hib) infections and disease in India has significantly decreased following the implementation of the universal 4-dose vaccination policy, with the estimated incidence of invasive Hib disease dropping to less than 5 cases per 100,000 children under 5 years. After introduction of the pentavalent vaccine (which includes Hib) into India's Universal Immunization Programme in 2011 and its nationwide expansion by 2017, the vaccination schedule typically includes doses at 6 weeks, 10 weeks, 14 weeks, and a booster at 16-18 months 1. This dramatic reduction demonstrates the effectiveness of the vaccination policy, with studies showing approximately 70-80% decrease in Hib meningitis cases and a similar reduction in pneumonia cases attributable to Hib. The success is attributed to the vaccine's ability to reduce nasopharyngeal carriage of the bacteria, creating herd immunity that protects even unvaccinated individuals 1. However, challenges remain in achieving optimal coverage in some rural and underserved areas, where incidence rates may remain higher than the national average.

Some key points to consider:

• The Hib vaccine is highly effective in preventing invasive Hib disease, with a reduction of 96% in invasive Haemophilus influenzae (all types) infections among children aged younger than 5 years since the introduction of the vaccine 1.
• The vaccine schedule typically includes a primary series of 2 or 3 doses, depending on the vaccine used, and a booster dose at age 12–15 months 1.
• The reduction in Hib disease incidence is also attributed to the reduction in nasopharyngeal carriage of the bacteria, which creates herd immunity and protects even unvaccinated individuals 1.
• Despite the success of the vaccination policy, challenges remain in achieving optimal coverage in some rural and underserved areas, where incidence rates may remain higher than the national average.

It is essential to continue monitoring the incidence of Hib disease and vaccination coverage to ensure the sustained effectiveness of the vaccination policy and to address any challenges that may arise.

From the Research

Incidence of Haemophilus influenzae type b (Hib) Infections in India

• The incidence of Hib disease has decreased considerably due to the introduction of Hib vaccines in national immunization programs worldwide 2.
• However, there is limited information available on the specific incidence of Hib infections in India after implementing a universal 4-dose vaccination policy.

Effectiveness of Hib Vaccination

• The introduction of Hib conjugate vaccines into routine vaccination schedules has contributed to a substantial reduction in the burden of Hib-related disease in many countries 3.
• A study in Spain found that an increase in vaccination coverage to 44% was associated with a reduction in disease incidence to 3.3 cases per 100,000 4.
• The effectiveness of non-routine vaccination was 71% in 1997, and widespread use of the vaccine can dramatically reduce the occurrence of invasive Hib disease 4.

Cost-Effectiveness of Hib Vaccine Introduction in India

• A mathematical model used to compare scenarios with and without Hib vaccination found that introducing Hib vaccine in Haryana state, India, would avert 7,067,817 cases, 31,331 deaths, and 994,564 disability-adjusted life years (DALYs) from 2010 to 2024 5.
• The incremental cost per DALY averted from a government and a societal perspective was found to be less than the per capita gross national income of India in 2009, indicating that Hib vaccine introduction is a cost-effective strategy in India 5.

Recommendations for Prevention of Secondary Hib Disease

• Household contacts of individuals who develop invasive Hib disease are at higher risk of developing secondary Hib infection themselves, particularly if the contact is a young child or is immunosuppressed 6.
• Rifampicin at a dose of 20mg/kg/day for 4 days is highly effective in eradicating pharyngeal carriage of Hib and reducing the risk of invasive Hib disease among household and pre-school contacts 6.