Epidemiology of pneumococcal meningitis in sentinel hospital surveillance of Viet Nam, 2015-2018

Background: Streptococcus pneumoniae (S. pneumoniae), Haemophilus influenzae (H. influenzae), and Neisseria meningitidis (N. meningitidis) are leading causes of childhood bacterial meningitis and preventable by vaccines. The aim of this hospital-based sentinel surveillance is to describe the epidemiological characteristics of pneumococcal meningitis, including disease burden, and to provide baseline data on pneumococcal serotype distribution to support decision making for pneumococcal conjugate vaccine (PCV) introduction in Vietnam.

Methods: Surveillance for probable bacterial meningitis in children 1-59 months of age is conducted in three tertiary level pediatric hospitals: one in Hanoi and two in Ho Chi Minh City. Cerebrospinal fluid (CSF) specimens were collected via lumbar puncture from children with suspected meningitis. Specimens were transferred immediately to the laboratory department of the respective hospital for cytology, biochemistry, and microbiology testing, including culture. PCR testing was conducted on CSF specimens for bacterial detection (S. pneumoniae, H. influenzae, and N. meningitidis) and pneumococcal serotyping.

Results: During 2015-2018, a total of 1,803 children with probable bacterial meningitis were detected; 1,780 had CSF specimens available for testing. Of 245 laboratory-confirmed positive cases, the majority were caused by S. pneumoniae (229,93.5%). Of those with S. pneumoniae detected, over 70% were caused by serotypes included in currently available PCV products; serotypes 6 A/6B (27.1%), 14 (19.7%), and 23 F (16.2%) were the most common serotypes. Children with laboratory-confirmed pneumococcal meningitis were more likely to live in Hanoi (p < 0.0001) and children 12-23 months of age were at greater odds (OR = 1.65, 95% CI: 1.11, 2.43; p = 0.006) of having confirmed pneumococcal meningitis compared to children < 12 months of age when compared to those without laboratory-confirmed bacterial meningitis. Additionally, children with confirmed pneumococcal meningitis were more likely to exhibit signs and symptoms consistent with clinical meningitis compared to negative laboratory-confirmed meningitis cases (p < 0.0001) and had a greater odds of death (OR = 6.18, 95% CI: 2.98, 12.86; p < 0.0001).

Conclusions: Pneumococcal meningitis contributes to a large burden of bacterial meningitis in Vietnamese children. A large proportion are caused by serotypes covered by PCVs currently available. Introduction of PCV into the routine immunization program could reduce the burden of pneumococcal meningitis in Viet Nam.