Conjugate versus polysaccharide meningococcal vaccine

Effect of Tdap upon antibody response to meningococcal polysaccharide when administered before, with or after the quadrivalent meningococcal TT-conjugate vaccine (coadministered with the 13-valent pneumococcal CRM197-conjugate vaccine) in adult Hajj pilgrims: A randomised controlled trial

Hajj pilgrims are susceptible to several serious infections and are required to receive multiple vaccinations. Polysaccharide-protein conjugate vaccines contain carrier proteins such as tetanus toxoid (TT), diphtheria toxoid or a mutant of diphtheria toxoid (CRM197). These carrier proteins may interact with other conjugate or combination vaccines containing tetanus or diphtheria on concurrent or sequential administration. We examined the immune interaction of separate and concomitant administration of a tetanus/diphtheria/acellular pertussis (Tdap) vaccine with a TT-conjugated quadrivalent meningococcal vaccine (MCV4) (coadministered with 13-valent pneumococcal CRM197-conjugate vaccine [PCV13]) in adult Australian pilgrims before attending Hajj in 2015. We randomly assigned each participant to one of three vaccination schedules. Group 1 received Tdap 3-4 weeks before receiving MCV4 coadministered with PCV13. Group 2 received all three vaccines concomitantly. Group 3 received MCV4 and PCV13 3-4 weeks before Tdap. Blood samples were collected at baseline, at each vaccination visit and 3-4 weeks after vaccination and tested for response to meningococcal serogroups C, W and Y using a serum bactericidal antibody (rSBA) assay with baby rabbit complement, and to diphtheria and tetanus toxoid, measuring IgG antibodies by ELISA. Participants completed symptom diaries after each vaccination. A total of 166 participants aged 18-64 (median 42) years were recruited, of whom 160 completed the study. Compared to the other groups, Group 1 (given Tdap first) had significantly lower proportion of subjects achieving a ≥4-fold rise in rSBA for serogroup W. No difference was detected across the three groups in achieving protection threshold (rSBA ≥8 post vaccination) or SBA geometric mean titre (GMT) post vaccination. Group 3, which was given MCV4/PCV13 first, had high levels of antibody against diphtheria and tetanus than the other groups, when tested prior to receipt of Tdap; Only the anti-tetanus responses remained significantly higher after Tdap administration. No serious adverse events were reported. In conclusion, when multiple vaccination is required for Hajj pilgrims, administering Tdap concurrently with MCV4/PCV13 produces adequate immune responses, and avoids meningococcal immune interference, in the convenience of a single consultation. However, giving Tdap 3-4 weeks after MCV4/PCV13 has the advantage of an enhanced tetanus toxoid response. The trial is Trials Registry (ANZCTR): ACTRN12613000536763.

Burden of vaccine preventable diseases at large events

BACKGROUND

Large events or mass gatherings (MGs) are known to amplify the risk of infectious diseases, many of which can be prevented by vaccination. In this review we have evaluated the burden of vaccine preventable diseases (VPDs) in MGs.

METHODS

Major databases like PubMed and Embase, Google Scholar and pertinent websites were searched by using MeSH terms and text words; this was supplemented by hand searching. Following data abstraction, the pooled estimate of the burden of VPDs was calculated when possible; otherwise a narrative synthesis was conducted.

RESULTS

In the past, at religious MGs like Hajj and Kumbh Mela, cholera caused explosive outbreaks; but currently respiratory infections, notably influenza, are the commonest diseases not only at Hajj but also at World Youth Day and Winter Olympiad. The recent cumulative attack rate of influenza at Hajj is 8.7% (range 0.7-15.8%), and the cumulative prevalence is 3.6% (range: 0.3-38%). Small outbreaks of measles (13-42 cases per event) have been reported at sport, entertainment and religious events. A sizeable outbreak (>200 cases) was reported following a special Easter Festival in Austria. An outbreak of hepatitis A occurred following the 'Jam bands' music festival. Other VPDs including pneumococcal disease, pertussis and tuberculosis have been reported in relation to MG attendance.

CONCLUSION

VPDs not only affect the participants of MGs but also their contacts; vaccine uptake is variable and vaccine implementation is likely to have beneficial effects. Research to address the knowledge gaps surrounding VPDs at MGs is needed.

Antibody persistence and response to a booster dose of a quadrivalent conjugate vaccine for meningococcal disease in adolescents

BACKGROUND

In a previous randomized phase 2 study in adolescents, a CRM197 meningococcal conjugate vaccine against serogroups A, C, W-135 and Y (MenACWY-CRM) was well tolerated and immunogenic, compared with a plain polysaccharide vaccine (MenACWY-PS).

METHODS

This extension study assessed antibody persistence 5 years after primary vaccination with MenACWY-CRM (n = 50) or MenACWY-PS (n = 51), and the immunogenicity and reactogenicity of a dose of MenACWY-CRM given 5 years after primary vaccination; antibody response was also compared with vaccine-naive controls (n = 54). The primary endpoints were the percentage of subjects with titers ≥8 by serum bactericidal activity assay using human complement (hSBA) 5 years after primary vaccination and hSBA geometric mean titers 1 month after the MenACWY-CRM dose given in the current study.

RESULTS

Five years after primary vaccination, over 70% of subjects who had received MenACWY-CRM were seropositive (hSBA titers ≥8) for serogroups C, W-135 and Y; for serogroups C and Y, the percentages of seropositive subjects were significantly higher in subjects previously vaccinated with MenACWY-CRM than in subjects previously vaccinated with MenACWY-PS. The MenACWY-CRM dose given 5 years postprimary vaccination elicited an anamnestic response across serogroups in those previously vaccinated with MenACWY-CRM. Responses in those previously vaccinated with MenACWY-PS were less robust but adequate and similar to that seen in the vaccine-naive group, both in magnitude and kinetics. MenACWY-CRM was well tolerated in all 3 groups.

CONCLUSION

MenACWY-CRM provided a broad and persistent immune response in adolescents. A subsequent dose of MenACWY-CRM elicited an adequate antibody response, regardless of vaccine history.

Influenza and meningococcal disease: lessons for travellers and government from 2 epidemic diseases

Influenza and meningococcal disease are two serious diseases that are especially linked. Outbreaks of influenza have been frequently associated with secondary outbreaks of meningococcal disease. Travellers such as Hajj pilgrims are at particular risk, the most recent meningococcal outbreaks being in 2000 and 2001, while concern is rising that the annual pilgrimage, centred as it presently is on winter, may even become the epicentre of an avian influenza pandemic. Routine vaccination of pilgrims against meningococcal disease using a 4-valent product has been in place since 2002 with good effect, but influenza vaccine is not yet routinely required for all pilgrims despite the high proportion afflicted. Meningococcal polysaccharide vaccines are effective in older children and adults and this cheaper product can play a role in the short term management of meningococcal outbreaks due to serogroups A, C, W135 or Y. The impressively fast development of a C conjugate vaccine in the late 1990s was a credit to the close collaboration of pharma, academia and the executive. A similar alignment could accelerate the production of an efficacious and cost-effective H5N1 influenza vaccine through direct transparent competition with head-to-head randomised, double-blinded controlled trials. Both organisms have a propensity to mutate and adapt to immune pressure. There are lessons to be learnt from how we manage each for the control of the other.