Pertussis and Transmission

Pertussis and Transmission

 I’m sure we’ve all seen the campaign ads called “Do it for your baby”. If not, here is an example. There is also a website.

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More recently, J. Lo was recruited by Sanofi Pasteur and the March of Dimes to jump on the bandwagon and promote Pertussis vaccines for adolescents and adults.

 Let’s take a look at the issue of Pertussis transmission and what the vaccine really does or doesn’t do.

Pertussis Infection in Fully Vaccinated Children in Day-Care Centers, Israel (Emerging Infectious Diseases (Vol. 6, No. 5, September–October 2000)

 Conclusions

 The effects of whole-cell pertussis vaccine wane after 5 to 10 years, and infection in a vaccinated person causes nonspecific symptoms (3-7). Vaccinated adolescents and adults may serve as reservoirs for silent infection and become potential transmitters to unprotected infants (3-11). The whole-cell vaccine for pertussis is protective only against clinical disease, not against infection (15-17). Therefore, even young, recently vaccinated children may serve as reservoirs and potential transmitters of infection.

 

…We found that immunity does not even persist into early childhood in some cases. We also observed that DPT vaccine does not fully protect children against the level of clinical disease defined by WHO. Our  results indicate that children ages 5-6 years and possibly younger, ages 2-3 years, play a role as silent reservoirs in the transmission of pertussis in the community. More studies are needed to find the immunologic basis of protection against infection and colonization and thus an effective way to eradicate pertussis.

 Also See:

Characterization of Bactericidal Immune Responses following Vaccination with Acellular Pertussis Vaccines in Adults

booster immunization of adults with acellular pertussis vaccines was not found to increase bactericidal activity over preimmunization levels. Identifying ways to promote bactericidal immune responses might improve the efficacy of acellular pertussis vaccines.

Informal consultation on the control of pertussis with whole cell and acellular vaccines

Dr Cherry pointed out in the 1999 WHO meeting, that even with a return to high vaccination coverage in Japan, pertussis incidence in children less than three months of age, had not declined substantially.

 

Pertussis toxin inhibits neutrophil recruitment to delay antibody-mediated clearance of Bordetella pertussis 

…However, their efficacy against subclinical infection is doubtful, as the majority of vaccinated populations test positive for subsequent infection (10, 17), suggesting that the bacterium successfully infects immune and/or vaccinated individuals.

  

The Pertussis vaccines do not prevent transmission or infection. It simply prevents or suppresses the symptoms, or causes subclinical infection. The reason the vaccines do not prevent transmission is because they do not kill the bacteria that cause the disease. The vaccines only make the body able to resist the toxin that the bacteria release. The toxin is what makes a person sick and causes clinical disease. That is the reason behind the claim that being vaccinated will make a clinical case of Pertussis ‘milder’. Even if you don’t get the full effect of the vaccine, you might get partial blockage of the toxin which might cause you to cough less, etc.

What is also worth noting is the small print of an advertisement for Adacel, a DTaP booster:

“It is unknown whether immunizing adolescents and adults against pertussis will reduce the risk of transmission to infants.”

At least there was some honesty there. The adolescent or adult booster helps one person, the person who receives it! Why doesn’t the campaign advertisement just say “Do it for you!” They don’t because time as shown repeatedly that the majority of adults will not do booster vaccines. But, if they use infants or children as a reason, it works.

 Read on…

 Acellular Pertussis Vaccines and Complement Killing of Bordetella pertussis

At least one of the antigens in the acellular pertussis vaccine appears to be able to serve as a target for complement-mediated bactericidal activity. However, in this study and other studies (19, 21), improved bactericidal responses after immunization were rarely observed, possibly due to induction of antibodies that fail to fix complement. The absence of vaccine-induced bactericidal activity in vitro is consistent with the observation that the pertussis vaccine is effective at preventing severe disease, likely due to pertussis toxin neutralization and blocking attachment to reduce bacterial colonization, but it is less effective at producing a sterilizing immune response (5, 18). Despite high vaccination rates, the number of reported cases of pertussis in the United States has increased steadily since the 1980s (22). Developing a pertussis vaccine with a greater potential to elicit bactericidal activity could reduce bacterial carriage and reduce the incidence of disease.

 

 According to this study, some were less likely to be protected, and the majorities were no more likely to be protected from infection than they were before the vaccine. To boot, the vaccine made them more susceptible to infection. There was a level of protection from severe disease due to the toxoid in the vaccine. This study alone shows that the vaccine doesn’t reduce carriage of the bacteria.  Therefore, marketing the vaccines solely to protect infants isn’t being entirely truthful. It simply does not work that way. The vaccine can’t stop you from being infected, nor stop you from spreading the bacteria to infants, the immuno-compromised, the unvaccinated or vaccinated.  

 

 It is also acknowledged that the whole-cell pertussis vaccine was more efficacious, but also more reactive, hence why we now use the DTaP.

Use of Pertussis Vaccines in Outbreaks

Estimates of the efficacy of immunization with pertussis vaccines are subject to wide variation due to variation in study design, including factors such as case definition, case ascertainment, and duration of follow up. A recent study of reported cases in the United States in 1992 – 1994 estimated the effectiveness of whole-cell vaccine against culture proven pertussis; the effectiveness of three doses among children aged 7-18 months was 79% and the effectiveness of 4 doses among children aged 19-47 months was 90%.2

Estimates are also available from recent field trials that compared the efficacy of acellular and whole-cell pertussis vaccines. In these trials, the efficacy of three doses of whole cell pertussis vaccines from different manufacturers ranged from 83% to 98%, although the DTP vaccine from one manufacturer had a low efficacy in two trials (35% to 48%). In the field trials, the efficacy of the four licensed acellular vaccines ranged from 71% to 89%.

 

 

When is a true case a case… or not? How does case definition come into play?

The Science and Fiction of Pertussis Vaccines  (PEDIATRICS Vol. 104 No. 6 December 1999, pp. 1381-1383)

Case definition has been particularly problematic in all of the recent DTaP vaccine efficacy trials. For uniform comparative purposes a case definition was suggested by a WHO expert committee. This definition required 21 days of paroxysmal cough plus laboratory confirmation of pertussis in the subject or household contact. There are 2 problems with this definition. The first is that a substantial number of B pertussis infections in unvaccinated children are mild and would not meet the case definition. The second is that all pertussis vaccines tend to modify duration and severity of disease rather than completely preventing illness. Therefore, the WHO definition has made all vaccines look better than they are and it has tended to obscure differences between vaccines.

 

Easily Missed?

Whooping cough is a common respiratory infection caused by the bacterium Bordetella pertussis. It should be considered as a possible diagnosis in any adolescent or adult with an acute cough of more than two weeks’ duration, even if they have been fully immunised.

 

Whooping cough in school age children with persistent cough: prospective cohort study in primary care

 

…Studies in the United States report a 20% incidence of Bordetella pertussis infection among adults with a persistent cough.2 Despite data showing that neither infection nor immunisation results in lifelong immunity, whooping cough is seldom diagnosed in primary care because of the lack of specificity of clinical symptoms and signs. Whooping cough is perceived as a disease of very young children who have not been immunised and who have classic features such as whoop…

…General practitioners should be alert to a potential diagnosis of whooping cough in any child who presents with a persistent cough. We found that children with pertussis cough for a median of 16 weeks. Little evidence indicates that administering erythromycin to children with pertussis two weeks after they have contracted the infection either reduces symptoms or prevents transmission.10

 

Acellular Pertussis Vaccines and Complement Killing of Bordetella pertussis 

 

When examined individually, the pre- versus postimmunization bactericidal activity was not significantly different at any dilution tested for 8 of the 15 acellular vaccine recipients. The individuals in the group with unchanged activity after immunization included an individual with undetectable preimmunization activity against the wild-type strain (individual 32-60), and the individual with the highest preimmunization activity (individual 26-47) (Fig. 2). These results suggest that the level of preimmunization bactericidal activity does not necessarily influence the ability to generate a postimmunization response.

 

However, statistically significant differences between pre- and post immunization bactericidal activity were observed (P < 0.05) using the paired t test for at least one serum dilution for 7 of the 15 acellular vaccine recipients. Furthermore, evidence of both improved bactericidal activity and reduced bactericidal activity after immunization was found in these seven serum samples. Four individuals displayed improved bactericidal activity after immunization when serum was added at lower concentrations (1.0 or 0.10%) but not at 10% (Fig. 3). However, in addition to enhanced bactericidal activity, individuals 4-43 and 20-55 displayed evidence of blocking activity, since fewer bacteria were killed when serum was added at 10% than when serum was added at 1%. Blocking activity could occur when antibodies that do not fix complement compete with complement-fixing antibodies for access to antigen. More definitive evidence of blocking was demonstrated in three other individuals (Fig. 4). For these individuals, the post immunization serum samples had significantly less bactericidal activity than the pre immunization serum samples at a serum concentration of 10%.

However, in this study and other studies (19, 21), improved bactericidal responses after immunization were rarely observed, possibly due to induction of antibodies that fail to fix complement. The absence of vaccine-induced bactericidal activity in vitro is consistent with the observation that the pertussis vaccine is effective at preventing severe disease, likely due to pertussis toxin neutralization and blocking attachment to reduce bacterial colonization, but it is less effective at producing a sterilizing immune response (5, 18).

 In various studies, vaccinated children do not fit the case definition of pertussis, yet they test positive. They exhibit atypical or mild symptoms. This shows the vaccine may protect against clinical disease, but not against infection.  Vaccinated children and adults are still serving as asymptomatic reservoirs and transmit infection.  A reduction in colonization, without any kind of sterilizing immune response, is the most you will get. There should be an enhanced bacterial clearance in the vaccinated, but studies have proved there isn’t. What is even worse is, serology states that more than half of are catching pertussis every 2 1/2 years. If humans did not transmit pertussis easily, or could clear it easier, we wouldn’t have it so much. The vaccine has not changed that. Vaccinated or not, you can and do, carry and transmit the disease.

 

 Other Studies:

 

Cell-mediated immune responses to antigens of Bordetella pertussis and protection against pertussis in school children  (Pediatric Infection Disease Journal 1999; 18: 366-370)

 Abstract

Background. Increasing evidence suggests that cell-mediated immunity (CMI) is involved in immune response against Bordetella pertussis. However, there are practically no studies evaluating the significance of pertussis-specific CMI in relation to protection against clinical pertussis.

 

On pg. 366: “The immunologic mechanisms of protection against clinical pertussis are poorly understood. Although several studies have suggested that antibodies to some pertussis antigens may be predictive of protection against pertussis, there is no generally accepted laboratory measure of immunity. Further in clinical efficacy trials of acellular vaccines, no clear correlation has been found between serum antibody values and protection. 

…”In the present study, no clear association was found between serum antibody values and clinical outcome.”

 

Pertussis toxin: the cause of the harmful effects and prolonged immunity of whooping cough. A hypothesis. (Rev Infect Dis. ;1 (3):401-12 233166)

The nature of the pathogenesis and of the prolonged immunity of whooping cough has not been clearly defined. The literature of Bordetella pertussis indicated that only the antigen that induces histamine sensitization, lymphocytosis, and other biological reactions in mice is the cause of the harmful effects and prolonged immunity of whooping cough. This antigen has the general characteristics of bacterial protein exotoxins that cause the harmful effects of infectious diseases such as diphtheria and tetanus. It is proposed that this antigen, which is histamine-sensitizing, lymphocyte-leukocyte-promoting, and islets-activating (HSF-LPF-IAP), be designated pertussis toxin. Agglutinogen, hemagglutinin, and heat-labile (at 56 C) and heat-stable (at 100 C) toxins are no doubt interrelated with the immunologic and/or toxic reactions of whooping cough. It appears that the first defense against the disease is the antibody that prevents adhesion of the bacteria to the cilia of the respiratory epithelium and that the second defense is the antitoxin against pertussis toxin (HSF-LPF-IAP).

 

 Those who have been vaccinated are still considered susceptible, unless they have had a natural case of Pertussis, because a natural case can protect them at a higher rate than the vaccine. A vaccine may give them a less severe case with exposure, but it has been shown repeatedly that it does not prevent transmission. The vaccine for adolescents and adults is solely to prevent them from getting a clinical case and passing it on the infant. But overall, it just extends the length of time before they do/can get it.

The vaccine can provide some ‘herd immunity’. How? It can postpone, suppress the disease, or make a less severe case. But herd immunity is limited. The chance of catching pertussis at some point in ones life is inevitable. People can also get Pertussis more than once. This natural cycle of the disease also provides herd immunity. Pertussis has virulent cycles of every 2-5 years and vaccines have not changed its natural virulence cycle.

 Underreporting of Pertussis has been acknowledged repeatedly. How does this correlate to the reduced disease burden? Simply put-It is only a guess.

Reemergence of Pertussis: Methods

 

Data from pertussis reporting (required by law since 1976) were obtained from 1976 to 1998 from the Inspectorate of Health. A case definition, introduced in 1988, included clinical symptoms and laboratory confirmation (or close contact with a person with laboratory-confirmed pertussis).

…From 1988 to April 1997, laboratory confirmation was defined as either a positive culture of B. pertussis (or B. parapertussis) or positive two-point serology, in turn defined as a significant rise of immunoglobulin (Ig) G antibodies against pertussis toxin or IgA antibodies against B. pertussis in paired sera. In April 1997, a positive polymerase chain reaction (PCR) and positive one-point serology were also accepted as laboratory confirmation. Positive one-point serology was defined as high IgG or IgA antibody titers in a single serum sample…

 

 Pertussis in Adults

 …In the prevaccine era, reported pertussis was a cyclic disease, with epidemic peaks every 2 to 5 years [9]. When pertussis was brought under control by vaccination of children in the 1960s in the United States and England and Wales, it was noted that the 2– to 5-year cyclic pattern continuedFailure of the pertussis cycle to lengthen led to Fine and Clarkson’s suggestion [11] that immunization controlled the disease in children but did not disrupt circulation of the organism. This observation and the knowledge that adults were a common source of disease in infants led our group and others to study the epidemiology of adult pertussis.

…contrast with our findings in the UCLA students (94% of whom had been vaccinated in childhood), we found that German adults (most of whom had not been vaccinated during childhood) were more likely to have typical pertussis with whooping and post-tussive vomiting [12]. Twenty-six percent of these adults had had pertussis during childhood.

Immunoglobulin A antibodies to B. pertussis antigens usually result from infection, not immunization. With this fact in mind, we examined the prevalence and degree of IgA antibody to four B. pertussis antigens in young adults in the United States and Germany [18]. We found that the mean titers and the prevalence of antibody to the four antigens were similar, suggesting that the circulation of B. pertussis in adults in the two countries was similar even though pertussis was epidemic in Germany and rare in the United States. In another study [19], in which we obtained serum samples yearly for 5 years from 51 persons, 90% of these persons had serologic evidence of at least one case of pertussis [19].

 

Essential Problems in Pertussis (Am J Public Health, Apr 1939; 29: 337 – 340).

…It would seem reasonable to expect that the case fatality of pertussis might have been favorably affected bv the better home hygiene, antirachitic and other nutritional advances in the dietaries of children, more general and skilled home nursing of patients during isolation, and other factors which we see applied for the benefit of children under 5 years of age, but there are, I believe, no studies to confirm these general impressions.

 

…Second, one finds a very considerable incompleteness of reporting, the extent of which varies widely according to the interest and adequacy of the local health and medical services of the community, from approximate completeness to about 5 per cent of estimated cases.

Third, one finds that routine departmental procedure in establishing the diagnosis and recording the presumed susceptibility, exposure, and subsequent history of infection in households where other children than the reported patient are living, is neither uniform nor adequate to permit study of the relative merits of isolation periods of different lengths, of inoculations intended to prevent, or of therapy designed to modify the course of the disease.

 

 Pertussis surveillance

…Surveillance is carried out in some countries, but is not done in any meaningful way in three quarters of the world. Surveillance data and coverage data are both unreliable. Reliable surveillance data are needed to check coverage and vaccine efficacy; both surveillance and coverage data are needed to monitor immunization programmes…

… There are two principal methods of estimating burden: the natural history method and the proportional mortality method. The general approach used by WHO to estimate disease burden is to start with an expert consultative process in order to develop a sound approach. The methodology should aim to use the best data available and seek to validate results with existing data. Sensitivity analysis and continuous critical review are the only guarantees that the approach is as sound as it can be.

The estimates continue to be refined as new information becomes available. The final product is a database of cases and deaths by age, sex, country and year, as well as a careful documentation of methods, assumptions, and data sources. The process should result in recommendations on how to improve the precision, robustness and usefulness of the estimates.

Factors that affect the estimates are epidemiologic, demographic and programmatic, as well as co-factors such as HIV prevalence and nutritional status. Other practical issues include the quality and generalizability of the input data. Validation of the estimates is always important. The process is often messy since reliable data may be lacking, broad extrapolations or generalizations are made, or there is a heavy reliance on “expert opinion”.

 

 Prevention of Pertussis among Adolescents by Vaccination: Taking Action on What We Know and Acknowledging What We Do Not Know

…But there is much that is not known about pertussis. It is unclear whether the recent increases in reported disease are real or are artifacts of increased recognition; the increase in reported cases among young infants, coupled with relatively stable rates of reported disease among older infants and preschool-aged children, suggests that there may be a real increase in the circulation of Bordetella pertussis in some age groups [1]. But there is no doubt that ascertainment of pertussis is variable and incomplete in most age groups. Physicians may not consider the diagnosis, especially in adolescents and adults, because of a lack of clinical awareness that pertussis occurs in these age groups. Diagnostic testing is imperfect, and some tests have not been well standardized. Culture of B. pertussis remains the gold standard by which other assays are judged, but unless the diagnosis is considered early in the course of illness and before administration of antimicrobial therapy, isolation of the bacterium is unlikely. Serological testing, once standardized, may facilitate diagnosis, but it remains unavailable in most areas, and assays based on PCR are variable in sensitivity and specificity [2]. Thus, our knowledge of the burden of pertussis is far from complete.

There is also much that we do not know about the dynamics of B. pertussis transmission. It is unclear what impact vaccinating young adolescents would have on disease incidence in other age groups. Do middle and high schools, with their high contact rates and susceptible populations, amplify B. pertussis circulation in the community? If routine vaccination of young adolescents prevented those outbreaks but immunity was not long lasting, would outbreaks then occur among young adults? Would transmission to young infants—the group with the highest morbidity and mortality due to pertussis—decrease or increase following implementation of an adolescent pertussis vaccination program? Mathematical modeling suggests that the impact of routine adult pertussis vaccination on the incidence of pertussis in young children may be relatively modest [3].

Because of these and other uncertainties, estimating the impact of pertussis vaccination of adolescents and adults on disease burden requires many assumptions….

 

Epidemiology of pertussis

 

 …In the majority of countries where pertussis is a notifiable disease, a case-based national surveillance system is in place. However, different case definitions, methods of diagnosis and reporting and surveillance systems make direct intercountry comparisons difficult, and pertussis is not a statutory notifiable disease in every country. Nevertheless the general consensus is that reported incidences are probably considerably lower than the actual incidence of pertussis; underreporting is common. Prolonged cough may be the only clinical feature in adolescents or adults, who may present for diagnosis late (precluding laboratory confirmation) or not at all. When they do present, their condition is often misdiagnosed because, in part, clinicians continue to perceive pertussis as a childhood disease.Despite underreporting, an increased incidence of infant, adolescent and adult pertussis has been observed worldwide since the introduction of widespread vaccination… 

 

 Also See:  Failure of Physicians to Consider the Diagnosis of Pertussis in Children

  

More on Adacel (11-64 years):

 Clinical Studies;

 

The efficacy of the tetanus toxoid and diphtheria toxoid used in Adacel vaccine was based on the immune response to these antigens compared to a US licensed Tetanus and Diphtheria Toxoids Adsorbed For Adult Use (Td) vaccine manufactured by Sanofi Pasteur Inc., Swiftwater, PA.

The protective efficacy against mild pertussis (defined as at least one day of cough with laboratory-confirmed B pertussis infection) was 77.9% (95% CI: 72.6%, 82.2%). (8) (9) In addition, the ability of Adacel vaccine to elicit a booster response to the pertussis antigens following vaccination was evaluated. The acellular pertussis formulations for Adacel and DAPTACEL vaccines differ only in the amount of detoxified PT (2.5 μg in Adacel vaccine versus 10 μg in DAPTACEL vaccine).

The primary measures of immunogenicity were (a) the percentage of participants attaining an antibody level of at least 0.1 IU/mL and (b) the percentage of participants achieving a rise in antibody concentration after vaccination (booster response). The demonstration of a booster response depended on the antibody concentration to each antigen prior to immunization.

 Threshold or “cut-off” values for antibody concentrations to each antigen were established based on the 95th percentile of the pre-vaccination antibody concentrations observed in previous clinical trials. A booster response was defined as a four-fold rise in antibody concentration if the pre-vaccination concentration was equal to or below the cut-off value and a two-fold rise in antibody concentration if the pre-vaccination concentration was above the cut-off value.

 The efficacy of the pertussis antigens used in Adacel vaccine was inferred based on a comparison of pertussis antibody levels achieved in recipients of a single booster dose of Adacel vaccine with those obtained in infants after three doses of DAPTACEL vaccine. In the Sweden I Efficacy Trial, three doses of DAPTACEL vaccine were shown to confer a protective efficacy of 84.9% (95% CI: 80.1%, 88.6%) against WHO defined pertussis (21 days of paroxysmal cough with laboratory-confirmed B pertussis infection or epidemiological link to a confirmed case).

 …Pregnancy Category C

 

Animal reproduction studies have not been conducted with Adacel vaccine. It is also not known whether Adacel vaccine can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Adacel vaccine should be given to a pregnant woman only if clearly needed…

Nursing Mothers

 

It is not known whether Adacel vaccine is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when Adacel vaccine is given to a nursing woman.

The safety and effectiveness of concomitant administration of Adacel vaccine with other vaccines has not been evaluated.

  

 Boostrix (10-18years)

 Prevention of Pertussis, Tetanus, and Diphtheria Among Pregnant and Postpartum Women and Their Infants

In 2006, ACIP recommended routine administration of Tdap for postpartum women who were not vaccinated previously with Tdap to provide personal protection and reduce the risk for transmitting pertussis to their infants (1,2) . After careful consideration, in June 2006, ACIP voted to reaffirm its recommendation for use of Td in pregnant women who have urgent indication for tetanus toxoid or diphtheria toxoid vaccination to prevent maternal or neonatal tetanus, or to prevent diphtheria. Pregnant women not vaccinated previously with Tdap will receive a measure of protection against pertussis by ensuring that children in the household are up-to-date with recommended doses of pediatric diphtheria and tetanus toxoids and acellular pertussis vaccine (DTaP)* (2123) and that adult and adolescent household contacts have received a dose of Tdap (Table 2) (1,2). Health-care providers can monitor pregnant women who have not received a dose of Tdap for exposures to pertussis or to respiratory illness consistent with pertussis, and they can administer antimicrobials for postexposure prophylaxis or treatment of pertussis, if needed, to reduce the risk for transmitting pertussis to their infants.

This report provides the background and rationale for routine administration of Tdap in postpartum women who were not vaccinated previously with Tdap and for maintaining the previous recommendation for use of Td in pregnant women if indicated. The safety and efficacy of using Tdap in pregnant women has not been demonstrated, and Tdap is not recommended for use in pregnant women in any country. No evidence exists of excess morbidity or any fatality among pregnant women ascribed to pertussis. No evidence exists demonstrating whether

  • Tdap in pregnant women harms the fetus or increases risk for adverse pregnancy outcomes,
  • transplacental antibody induced by Tdap administered during pregnancy will protect infants against pertussis, or
  • Tdap-induced transplacental maternal antibody will have a negative impact on an infant’s protective immune response to later-administered routine pediatric DTaP or to conjugate vaccines containing tetanus toxoid or diphtheria toxoid.

Health-care providers should weigh the theoretical risks and benefits before choosing to administer Tdap vaccine to a pregnant woman…

…The specific issues for pertussis differ from those for tetanus and diphtheria. Important among these is the limited understanding of immunity and correlates of protection for pertussis. In addition, data supporting the safety of vaccinating pregnant women with Tdap to prevent pertussis are scarce for women, their fetuses, and pregnancy outcomes. Whether transplacental maternal antibody exerts an inhibitory or other effect on the infant-protective immune response to active immunization with pediatric DTaP or conjugate vaccines containing tetanus toxoid or diphtheria toxoid has not been studied. Protection against infant pertussis through Tdap-induced transplacental maternal antibody has not been demonstrated. Until additional information is available, the majority view of the working group held that Tdap administered to women in the immediate postpartum period, in addition to ensuring pertussis vaccination of close contacts, would likely provide a measure of protection for mother and infant.

 

Vaccinating Pregnant Women against Pertussis

Tdap:

No prelicensure studies were conducted with Tdap in pregnant women. In 2005, to increase understanding of the safety of Tdap in relationship to pregnancy, both Tdap manufacturers established registries to solicit voluntary reports of pregnant women who received Tdap during pregnancy or who received Tdap and were determined subsequently to be pregnant (212,213). The main utility of the registries is to signal the possibility and nature of any risk (214). All women who are vaccinated with Tdap at any time during pregnancy should be reported to the registry as early as possible during the pregnancy. Information from pregnancy registries differs from surveillance reports, which are used to evaluate outcomes among women when an adverse outcome of pregnancy already might have occurred (e.g., an infant born with a birth defect) (214).

Also see: Guidelines for Vaccinating Pregnant Women (ACIP Guidelines May 2008) 

  • Pregnancy is not a contraindication for use of Tdap. Data on safety, immunogenicity and the outcomes of pregnancy are not available for pregnant women who receive Tdap. When Tdap is administered during pregnancy, transplacental maternal antibodies might protect the infant against pertussis in early life. They also could interfere with the infant’s immune response to infant doses of DTaP, and leave the infant less well protected against pertussis. 11
  • ACIP recommends Td when tetanus and diphtheria protection is required during pregnancy. In some situations*, healthcare providers can choose to administer Tdap instead of Td to add protection against pertussis. When Td or Tdap is administered during pregnancy, the second or third trimester is preferred. 11
  • Providers who choose to administer Tdap to pregnant women should discuss the lack of data with the pregnant women and are encouraged to report Tdap administrations regardless of the trimester, to the appropriate manufacturer’s pregnancy registry: for Boostrix® to GlaxoSmithKline Biologicals at 1-888-825-5249, or for Adacel®, to sanofi pasteur at 800-822-2463. 11
  •  

    It appears there is much they ‘don’t know’. But that isn’t stopping them. Vaccinating Post-partum Mothers before leaving the hospital with Tdap, even if they are breastfeeding, has been increasing.

    Investigators in Houston have successfully implemented a novel vaccination strategy – vaccinating women who have just given birth to prevent them transmitting pertussis (whooping cough) to their young infants.  This study took place in a medically underserved and underinsured population.   Study investigators gave tetanus, diphtheria and acellular pertussis (Tdap) vaccine to over 1000 mothers at Ben Taub General Hospital, a county hospital that serves a predominantly Hispanic population in Houston, over a 3 month period.  Approximately 75% of women who were offered Tdap received the vaccine and when Tdap was not administered it was usually because mothers had received a recent tetanus vaccine (a relative precaution to receiving Tdap vaccine).  This program is, to our knowledge, the first to implement and track on a large scale the 2006 Centers for Disease Control and Prevention (CDC) recommendation that women receive Tdap before they leave the hospital after delivery.

    Also see: Forrest General gives recommended vaccine for new mothers

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