Comparison of the Immunogenicity of the 3+1 Schedule and the 2+1 Schedule of 7-valent Pneumococcal Conjugated Vaccine in Young Chinese Infants

Detailed Summary

Pneumonia is one of the most prevalent diseases in infants and children. The incidence of pneumonia in children less than 5 years old is about 34-40 cases per 1000 in Europe and America and more than 2 million children die of pneumonia annually. It was reported that Streptococcus pneumoniae accounted for 13%-53% of lower respiratory tract infections in different age group of infants or children. In addition, 7%-9% of bacterial meningitis was due to Streptococcus pneumoniae infection. In addition, children infected with Streptococcus pneumoniae often transmit the pathogens to adult. As a result, it is evident that Streptococcus pneumoniae presents a heavy burden to paediatrics practice. Vaccination of 7-valent pneumococcal conjugate vaccines is effective in preventing Streptococcus pneumonia .Routine use of PCV7 in the US has rapidly reduced rates of invasive pneumococcal disease in children. The impact of the vaccine was noted within 1 year of introduction. According to Centre for Disease Control's (CDC) Active Bacterial Core Surveillance (ABCs) the incidence of invasive pneumococcal disease among children \<5 years dropped 75% from 1998/1999 to 2005; disease caused by vaccine-type strains fell 94% from 80 to 4.6 per 100,000. Currently there are two immunization schedules: manufacturer recommended the 3+1 schedule and many countries adopted a 3 dose schedule, either 3+0 or 2+1 schedules. In US, it is recommended to give three doses during infancy (scheduled at 2, 4, 6 month) plus one dose at 12-15 months (3+1 schedule). Since several studies have demonstrated that two doses may provide similar direct protection to three conjugate doses during infancy, it is recommended to give two doses during infancy plus a booster dose 12 months in some European countries including United Kingdom. In this trial, the immunogenicity of the 3+1 schedule and the 2+1 schedule of 7-valent pneumococcal conjugated vaccine in young infants will be compared.

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