Strategies and new developments to control pertussis, an actual health problem

Effectiveness of strategies to increase uptake of pertussis vaccination by new parents and family caregivers: A systematic review

OBJECTIVES

Cocoon immunisation strategies involve administration of Bordetella pertussis containing vaccines to parents and family members who are in close contact with newborns. The objective of this systematic review was to evaluate the effectiveness of strategies to increase uptake of vaccination against Bordetella pertussis infection by parents and family caregivers of newborn children (< 3 months of age).

DESIGN

A protocol driven systematic review was conducted between 2005 and February 2020. CINAHL, Medline, and Google Scholar databases were searched.

SETTING

Inpatient maternity care units, ante-natal and post-natal clinics based in acute care or primary/community care contexts.

PARTICIPANTS

(i) mothers, (ii) fathers and (iii) family caregivers or other regular household contacts of infants < 3 months of age.

INTERVENTIONS

Health promotion interventions and immunisation clinics designed to promote "cocoon immunisation" against Bordetella pertussis infections of the newborn.

MEASUREMENTS

Change in uptake of adult vaccination with a pertussis containing vaccine (dTpa or Tdap) by new parents and family caregivers.

FINDINGS

Eight studies were included in this review. Strategies used to promote vaccination included: written and verbal education, promotional videos, provision of vaccine prescriptions and financial incentives, opportunistic vaccination of family members and population-based health promotional messaging. Six of the eight studies reported positive impacts on vaccination uptake. Four studies evaluating providing opportunistic immunisation during the obstetric admission reported statistically significant increases in maternal (+39% to +57%), paternal (+21% to +52%) and household members (+32%) vaccination rates. Targeted public health campaigns were also found to increase vaccination uptake but in isolation were insufficient to achieve vaccination of all household contacts.

CONCLUSION

Promotion of pertussis vaccination to new parents and the provision of opportunistic vaccination during the obstetric admission or post-natal visit, was the most successful strategy to increase uptake of pertussis vaccination by family caregivers.

Routine Childhood Vaccines Given in the First 11 Months of Life

The US Advisory Committee on Immunization Practices recommends that infants beginning at birth receive several vaccines directed against a variety of infectious diseases that currently pose threats of morbidity and mortality to infants and those around them, including the 3-dose hepatitis B (HepB) series. The first dose is due at birth. This series protects against maternal-infant transmission of the HepB virus and against exposure the rest of the infant's life. At age 2 months infants are to receive not only their second dose of HepB vaccine but also a series of vaccines directed against diphtheria, tetanus, pertussis, pneumococcus, rotavirus, poliovirus, and Haemophilus influenzae type b. At 4 months, infants are to repeat those vaccines except for the HepB vaccine. At age 6 months infants are to finish the HepB series and receive the third doses of the other vaccines received at 2 and 4 months except for the rotavirus vaccine, depending on the brand used. Also, starting at 6 months, depending on the time of year, infants are to begin a 2-dose series against influenza separated by 28 days. Each of these vaccines is due at a time when the vaccine works to protect against an immediate risk and to provide long-term protection. These vaccine-preventable diseases vary in terms of the nature of exposure, the form of the morbidity, the risk of mortality, and the ability of routine vaccination to prevent or ameliorate harm.

A novel method for the extraction of outer membrane vesicles (OMVs) from Bordetella pertussis Tohama strain

BACKGROUND AND OBJECTIVES

There are many pertussis outbreaks which is mainly due to the reduction in the immunity of acellular pertussis (aP) vaccines. Therefore, there is a crucial necessity to develop a new generation of pertussis vaccine. Preceding researches have shown that Bordetella pertussis outer membrane vesicles (OMVs) have appropriate specifications, making them a suitable vaccine candidate against pertussis.

MATERIALS AND METHODS

The OMVs were separated by a new serial ultra centrifugation technique. Transmission electron microscopy (TEM) examination, SDS-PAGE, Western blotting and ELISA assay were used to characterize the OMVs.

RESULTS

TEM studies showed the size of the extracted OMVs at 40-200 nm. The presence of pertussis toxin, filamentous hemagglutinin, and pertactin was verified using Western blot and ELISA assay.

CONCLUSION

The presented technique is a simple and effective way to obtain OMVs from Bordetella pertussis. So it can be utilized as an appropriate procedure in the development of an OMV-based vaccine against pertussis.

Vaccinations against respiratory infections in Arabian Gulf countries: Barriers and motivators

AIM

To study the uptake, barriers and motivators of influenza, pneumococcal, meningococcal and pertussis vaccines among members of public in Arabian Gulf countries.

METHODS

A cross-sectional survey among the Gulf Cooperation Council (GCC) countries’ residents. Data collected electronically through a smartphone app. The survey variables aimed to investigate the respondents’ awareness about vaccines against influenza, pneumococcal, meningococcal and pertussis infections. Collected data concerning the respondents’ socio-demographic characteristics, their perception toward vaccine uptake and the factors that motivate or demotivate them from taking influenza vaccine. The data were analysed statistically using the SPSS v.23.0. Differences in the characteristics of users from different countries were quantified through bivariate analysis. Other important variables and controlling factors were studied using logistic regression.

RESULTS

A total of 1812 respondents participated in the study. Their mean age was 27 years, 82% were male and 24% had ≥ 1 chronic diseases. The overall uptake of influenza vaccine was 17% (21% among “at risk” people) and ranged from 15% in Saudi Arabia to 24% in Qatar. Doctor’s advice (23%) and a perception of having low body immunity (21%) were the main cited reasons for being vaccinated, whereas unawareness about the vaccine (43%) was the main barrier. The overall uptake of pneumococcal vaccine in the preceding three years was 22% (25% among “at risk” individuals) and ranged from 0% in Bahrain to 79% in Kuwait. The overall uptake of pertussis vaccine was 16% (31% among “vulnerable” people), and ranged from 7% in Saudi Arabia to 75% in Oman. The overall uptake of meningococcal vaccine was 20% (29% among the “at risk” people) and ranged from 3% in Oman to 50% in Bahrain.

CONCLUSION

The vaccination uptake across GCC countries is suboptimal and varies widely across the countries. Further research is needed to unearth the reasons and formulate action plan.

cAMP Signaling of Adenylate Cyclase Toxin Blocks the Oxidative Burst of Neutrophils through Epac-Mediated Inhibition of Phospholipase C Activity

The adenylate cyclase toxin-hemolysin (CyaA) plays a key role in immune evasion and virulence of the whooping cough agent Bordetella pertussis. CyaA penetrates the complement receptor 3-expressing phagocytes and ablates their bactericidal capacities by catalyzing unregulated conversion of cytosolic ATP to the key second messenger molecule cAMP. We show that signaling of CyaA-generated cAMP blocks the oxidative burst capacity of neutrophils by two converging mechanisms. One involves cAMP/protein kinase A-mediated activation of the Src homology region 2 domain-containing phosphatase-1 (SHP-1) and limits the activation of MAPK ERK and p38 that are required for assembly of the NADPH oxidase complex. In parallel, activation of the exchange protein directly activated by cAMP (Epac) provokes inhibition of the phospholipase C by an as yet unknown mechanism. Indeed, selective activation of Epac by the cell-permeable analog 8-(4-chlorophenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate counteracted the direct activation of phospholipase C by 2,4,6-trimethyl-N-[3-(trifluoromethyl)phenyl]benzenesulfonamide. Hence, by inhibiting production of the protein kinase C-activating lipid, diacylglycerol, cAMP/Epac signaling blocks the bottleneck step of the converging pathways of oxidative burst triggering. Manipulation of neutrophil membrane composition by CyaA-produced signaling of cAMP thus enables B. pertussis to evade the key innate host defense mechanism of reactive oxygen species-mediated killing of bacteria by neutrophils.

Characterization of the immune response induced by pertussis OMVs-based vaccine

For the development of a third generation of pertussis vaccine that could improve the control of the disease, it was proposed that the immune responses induced by the classic whole cell vaccine (wP) or after infection should be used as a reference point. We have recently identified a vaccine candidate based on outer membrane vesicles (OMVs) derived from the disease etiologic agent that have been shown to be safe and protective in mice model of infection. Here we characterized OMVs-mediated immunity and the safety of our new candidate. We also deepen the knowledge of the induced humoral response contribution in pertussis protection. Regarding the safety of the OMVs based vaccine (TdapOMVsBp,) the in vitro whole blood human assay here performed, showed that the low toxicity of OMVs-based vaccine previously detected in mice could be extended to human samples. Stimulation of splenocytes from immunized mice evidenced the presence of IFN-γ and IL-17-producing cells, indicated that OMVs induces both Th1 and Th17 response. Interestingly TdapOMVsBp-raised antibodies such as those induced by wP and commercial acellular vaccines (aP) which contribute to induce protection against Bordetella pertussis infection. As occurs with wP-induced antibodies, the TdapOMVsBp-induced serum antibodies efficiently opsonized B. pertussis. All the data here obtained shows that OMVs based vaccine is able to induce Th1/Th17 and Th2 mixed profile with robust humoral response involved in protection, positioning this candidate among the different possibilities to constitute the third generation of anti-pertussis vaccines.