Childhood flu shots could result in serious clinical outcomes in adults: Study

MSD presented two new review studies at the 9th International Symposium of Pneumococci and Pneumococcal Diseases (ISPPD). The first review, abstract 132, shows a growing difference in the proportion of serotypes included in the 23-valent pneumococcal polysaccharide vaccine (PPSV23), compared to the 13-valent pneumococcal conjugate vaccine (PCV13), following widespread paediatric PCV vaccination programmes. The second review, abstract 133, shows how individual pneumococcal serotypes among adults have greater or lesser risk of causing serious clinical outcomes.1

“The findings from these reviews show how the epidemiology of IPD serotypes is changing after the introduction of PCV7 into childhood immunisation programmes in multiple countries. The differences appear to be widening further with more extensive paediatric use of PCV10 or PCV13. Also, there are certain serotypes which have repeatedly been found to be associated with elevated risk of serious outcomes in adults. Clinicians and policy makers should consider these differences in relevance to circulating serotypes to which adults are vulnerable to maximise the value provided to vaccine recipients,” said John Grabenstein, MSD scientist.

A systematic literature review was conducted to identify differences in proportions and incidence of invasive pneumococcal disease (IPD) serotypes present in PPSV23 and PCV13 before and after widespread pediatric use of PCV7.2 One part of review included data from 16 countries including India. The Indian data came from IBIS-2 (Invasive Bacterial Infection Surveillance) study done by Kurien T et al 2013 during his career at Christian Medical College (CMC), Vellore. The India-specific data for adults =61-year-old found a difference of 24 per cent between PPSV23 and PCV13. The investigators concluded that the paediatric vaccination has led to a widening difference in the amount of invasive pneumococcal disease that can be targeted by the two vaccines.

In the second literature review, pneumococcal serotypes associated with elevated risk in adults were identified across the world. The results showed that some serotypes are statistically more likely to cause serious diseases like pus in chest (empyema), inflammation of membranes of brain (meningitis), infection with low blood pressure (septic shock), or elevated case-fatality rates, compared to other pneumococcal serotypes.3 The investigators grouped the serotypes associated with elevated risk of serious clinical outcomes according to which vaccines are targeted against them: PPSV23 and/or PCV13.

The study concluded that:

• Multiple pneumococcal serotypes associated with increased risk for serious outcomes in adults are included in both PPSV23 and PCV13, notably serotypes 1, 3, 6B, 19F, 19A and 23F.4
• Nine of 11 serotypes unique to PPSV23 were linked with elevated risk for serious disease across 14 studies reviewed.4
• Serotype 6A, which is unique to PCV13, was linked in the analysis with elevated risk for serious disease in three studies only.4
• Serotypes 11A and 9N (unique to PPSV23 ) were repeatedly linked with elevated case-fatality rates in adults.4
• Serotypes 10A and 15B (unique to PPSV23) were repeatedly linked with elevated risk of pneumococcal meningitis in adults.4
• PPSV23 is indicated for vaccination against pneumococcal disease caused by those pneumococcal types included in the vaccine (1, 2, 3, 4, 5, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19F, 19A, 20, 22F, 23F, and 33F).

References:
1. Grabenstein Spn Serotype Delta Poster Adult, p1A, 3A, Grabenstein Spn Serotype Danger Poster, p1A, 2A]
2. Grabenstein Spn Serotype Delta Poster Adult p1B,2A
3. Grabenstein Spn Serotype Danger Poster p.2A
4. Grabenstein Spn Serotype Danger Poster p.4A

EP News Bureau – Mumbai