Advisory committee on immunization practices




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Opposed: None

Abstained: None


The vote passed.


Tdap Use in Pregnancy

Presenter: Dr. Trudy Murphy, N.I.P.


Overview: There was divergence of opinion on the Working Group about the use of Tdap during pregnancy, to be discussed in greater depth at the February meeting. Language options as place holders until that later discussion were presented.


Option 1 Summary, Tdap during pregnancy to protect against tetanus

“Tdap is preferred to Td for protection against tetanus if greater than 10 years since last tetanus toxoid-containing vaccine; Td is an acceptable alternative. Vaccination in the 2nd or 3rd trimester is preferred for both Tdap and Td. Providers are encouraged to report women vaccinated with Tdap during pregnancy to the sanofi pasteur registry.”


Option 2 - Tdap during pregnancy for protection against tetanus and pertussis. There were no negative responses among the Working Group to the following language. Option 2 allows Tdap to be used at intervals less than 10 years after the last tetanus toxoid-containing vaccine, in settings with increased risk of maternal exposure to pertussis:


“For protection against tetanus, Tdap is preferred (Option 1). Tdap may be considered at intervals shorter than 10 years after the last tetanus toxoid containing vaccine in settings with increased risk of maternal exposure to pertussis.”


Discussion:

  • Dr. Keith Powell reported that the A.A.P.’s C.O.I.D. will issue a statement, either later this year or early next year, recommending Tdap for adolescents regardless of pregnancy status.

  • While this text was not a recommendation, its wording on tetanus would be that of the adolescent recommendation (that is, if tetanus protection is needed, Tdap can be given rather than Td). But if a tetanus booster is not needed (that is, less than 10 years since last tetanus toxoid injection), Tdap may be considered for this shorter interval in settings of increased risk of maternal exposure to pertussis.

  • Dr. Baker asked why pregnant teens were being addressed differently. Dr. Murphy explained that, since the pertinent data were not presented at the last meeting, the Working Group had planned to do present the information at this meeting. Approximately10 percent of U.S. births are to adolescent mothers. Data are insufficient to definitively resolve whether the vaccinated mother’s high antibodies could interfere with the infant’s immune response to the primary series of D.T.a.P. vaccine. The main problem is that pertussis, unlike other diseases, does not have a good correlate of protection; it is not possible to know if antibody actively transported to the infant provides protection. These concerns will be discussed in February

  • Dr. Wexler suggested, rather than “maternal exposure,” saying “prenatal exposure,” or, Dr. Baker suggested, “exposure to pertussis by pregnant women.”


Dr. Morita moved to accept Option 2 as a placeholder until the February meeting. The motion was seconded by Mr. Beck


Vote

In favor: Allos, Beck, Campbell, Finger, Gilsdorf, Hull, Lieu, Marcuse, Morita, Treanor, Womeodu, Abramson

Opposed: None

Abstained: None


The vote passed.


Possible Association of M.C.V.4 (Menactra®) with G.B.S.

Presenter: Dr. John Iskander, on behalf of the Guillain-Barré Syndrome (G.B.S.) Investigation Team (C.D.C., F.D.A., C.I.S.A. Network)


Overview: V.A.E.R.S. reports of G.B.S. after Menactra® vaccination; some key clinical and epidemiologic features; G.B.S. incidence among 11 to 19 year-olds (internationally); planned controlled studies of the V.A.E.R.S. signal.


The quadrivalent meningococcal vaccine, Menactra,® was F.D.A.-licensed in January 2005 for use in those aged 11 to 55 years. It is a polysaccharide-diphtheria toxoid conjugate vaccine comprising polysacharrides of meingococcal serogroups A, C, Y, and W-135. The A.C.I.P. in February recommended its routine use at the preadolescent visit and high school entry, among college freshmen living in dormitories, and for other high-risk groups (for example, travelers, military recruits, immunodeficient individuals, and laboratory microbiologists).


Meningococcal disease occurs in a natural cycle, and 2005 is a trough year. The rate for 11 to 30 year-olds is approximately 0.5 per 100,000, and vaccination impact is not yet evident. By October 24, V.A.E.R.S. had recorded six cases of Guillain-Barré Syndrome (G.B.S.) after Menactra® vaccination. These occurred in different states during June or July, and involved five different vaccine lots. Sanofi pasteur provided data on the 2.7 million Menactra® doses distributed through October 20, 2005. Because purchases have been restricted since late May, little vaccine is likely to have been stored. The four states reporting the first five G.B.S. cases accounted for 24 percent percent of the doses distributed.


G.B.S. is a serious neurologic disorder involving peripheral nerve demyelination. It begins with subacute but progressive, symmetrical weakness, along with areflexia. Sensory and/or cranial nerve abnormalities may emerge, and paralysis of respiratory muscles can ensue. About 5 percent of those afflicted die and approximately 20 percent of survivors may have prolonged disability. G.B.S. can occur spontaneously or after antecedent events (for example, infections or vaccinations), but up to 66 percent of cases in large case series studies identified no antecedent infection or other event. Of those that were found, Campylobacter jejuni infection preceded in 20 percent to 40 percent of cases. G.B.S. has also been linked to cytomegalovirus, Epstein-Barr virus and Mycoplasma pneumoniae infections.


Clinical and epidemiologic features. All the V.A.E.R.S. case report patients were 17 to 19 years old and all symptoms began 2 to 5 weeks after M.C.V.4 vaccination. One patient had two prior episodes of post-vaccination (not meningococcal) G.B.S., and one had known acute illness (not gastrointestinal) before symptom onset. None had another known infectious etiology, but testing for infectious etiologies was limited. One patient was intubated. All have recovered or are recovering.

All these events occurred 2 to 6 weeks post-vaccination, paralleling the time course of G.B.S. during the 1976 to 1977 swine influenza vaccination program. The latter’s attributable risk was finally determined to be about 1:100,000. The two week latency of several cases is consistent with a causative role for vaccination, and is further supported by a statistical disproportionality of V.A.E.R.S. G.B.S. reports after Menactra,® compared to other vaccines.


G.B.S. incidence in 11 to 19 year-olds. Data from the V.S.D. and the Health Care Utilization Project (HCUP, tracking hospitalization) indicate a G.B.S. incidence of approximately 1-2 per 100,000 person-years. That rate is consistent across countries and seasons for this age group, making the G.B.S. rate inferred from V.A.E.R.S. similar to the expected background rate. But the timing of symptom onset remains of concern and V.A.E.R.S.’ underreporting is unknown. During the era in which oral poliovirus vaccine (O.P.V.) was still used in the U.S., a study published in 1996 (Rosenthal and Chen, American Journal of Public Health) found that 68 percent of vaccine-associated paralytic poliomyelitis (V.A.P.P.) were reported to V.A.E.R.S.; as this is a clinical syndrome similar to G.B.S., that might be the upper confidence bound. The lower bound may parallel that of influenza vaccine-associated G.B.S. studied with a capture/recapture methodology ─ approximately 5 percent.


Data relevant to this issue were outlined.

  • Pre-licensure studies did not indicate any G.B.S. incidence. V.S.D. data were queried for any incident cases of G.B.S. following administration of Menactra. No such cases were found at any V.S.D. site; at two sampled sites, 85 to 95 percent of vaccines had at least six weeks of follow-up. However, such data cannot rule out a rare association, such as 1:100,000.

  • U.K. data cover three different (tetanus-toxoid, nontoxic diphtheria toxin mutant, CRM) meningococcal C conjugate vaccines used between 1999 to 2005. Of 30 million doses to persons aged less than 18 years, only five G.B.S. reports emerged from enhanced spontaneous reporting ─ significantly less than expected.


In view of insufficient evidence that M.C.V.4 causes G.B.S. and an ongoing risk of serious meningococcal disease, C.D.C. advised continuation of the current vaccination strategies, except to avoid vaccination of persons not at high risk who had a prior history of G.B.S. The ongoing investigation was made part of the vaccine-risk communication process. C.D.C. encouraged health departments to strengthen surveillance and to report possible cases of G.B.S. after M.C.V.4 vaccination to V.A.E.R.S. G.B.S. surveillance among adolescents was enhanced consistent with state and local disease-reporting guidelines. There are currently a small number of states in which G.B.S. is a reportable condition.


Aside from the M.M.W.R. notice, Sanofi pasteur has written to providers, updates its web site information regularly, and has updated the package insert to add this possible association. A revised interim vaccine-information statement (VIS) has been disseminated.

M.M.W.R. reported in October another confirmed G.B.S. case under investigation; one additional unreported case, with confirmed EBV infection, had onset greater than 4 months after Menactra® administration. No additional G.B.S. reports have been received by V.A.E.R.S., although one confirmed and one suspected report of transverse myelitis were reported.


The interim G.B.S. case definition developed by the G.B.S. investigation team includes clinical case definitions stratified by levels of diagnostic certainty, clinical and laboratory elements, and a surveillance case definition to aid active case-finding, and will be disseminated to key partners and stakeholders.


Planned studies. This potential V.A.E.R.S. signal will be evaluated in several planned controlled studies: a national retrospective cohort study using multiple, large managed-care databases, and a national-case control and case-series analysis. Both the large cohort study and expanded active and case-finding surveillance will be used to identify cases.


The study protocol is in development and an oversight committee will review it. The primary objectives are to determine whether an association exists between G.B.S. and Menactra® administration, and if so, to quantify the attributable risk. Secondary study objectives will assess non-vaccine risk factors for G.B.S. and attempt to assess the degree of underreporting to V.A.E.R.S. of M.C.V.4-associated G.B.S. Key communication resources were outlined, such as a new N.I.P. Website portal and new links on the Sanofi pasteur site.


Discussion:

  • Dr. Paul Offit asked about the post-administration timing for the confirmed transverse myelitis case (it was within the 2 to 6 week window), and whether transverse myelitis is part of the G.B.S. investigation. Both are demyelinating diseases, one affecting the C.N.S. and the other the peripheral nervous system. Dr. Iskander responded that the approach would focus on G.B.S., but also consider transverse myelitis.

  • Dr. Allos raised G.B.S.’ year-to-year clustering, as well as its seasonality. She also noted that, although it has a culture-proven association with Campylobacter, infected individuals can be asymptomatic, so a diary of illness may not be valid. Finally, she commented that the cases’ disease concentration in young males greatly paralleled that of Campylobacter jejuni. The sex, age, and seasonal similarities need to be examined before any conclusions can be drawn. Dr. Isakander clarified that the broader analysis smooths out incidence over geographic areas. While relatively little year-to-year variation arose, there were gross ecologic similarities between the groups that might be at risk for Campylobacter and G.B.S.

  • Dr. Cherry noted the same similarities with enteroviruses and asked if serology looked for that. Dr. Iskander said that even the fairly large studies found no serologic antecedents to infection 60 to 70 percent of the time. However, not all cases in V.A.E.R.S. had a full battery of tests and there were reporting delays. But, since the average G.B.S. case does not have proven antecedent etiology, the absence of one on an individual level neither argues for nor against a vaccine etiology for that particular case.

  • The encouragement to report G.B.S. cases produced almost no increase. The signal could have been false or could represent a rare association on the order of 1 per 100,00 or less

  • Dr. Baker congratulated C.D.C. for its response to this signal. She asked what the set point for the attributable risk would be to determine that this was a vaccine-associated event, rare as it is. Frank DeStefano, of the Immunization Safety Office, related that perhaps approximately 200 G.B.S. cases have occurred in the approximately 6 months since the vaccine’s release. Even if all those cases could be enrolled, at best the detectable relative risk would range from 2.0 to 4.0. More realistically, the 50 to 100 cases that may emerge from the large managed-care organization and extensive case finding could produce a relative risk of 5.0 to 10.0. While there may not be sufficient power to determine a statistically significant association, there may be enough to set an upper bound.

  • Dr. Turner reported the A.C.H.A.’s email about the enhanced G.B.S.-Menactra® surveillance to their college health associates. No cases were reported among the approximately 6 to 7 million college students in their care. He offered access to the A.C.H.A.’s large centralized database of several million students for future C.D.C. studies.

  • Dr. Geoff Evans asked about the role of C.I.S.A., a C.D.C.-funded group of academic vaccine specialists who conduct case-level investigations. They act as C.D.C.’s “clinical eyes and ears” to accumulate the best possible case histories and case reviews, operating in a research framework and an informed consent setting. If there are no reporting delays, they can get critical information such as serologic samples, but it is very hard to get real time information. The I.O.M. found a possible association between tetanus toxoids and brachial neuritis and G.B.S. through a case series approach, but it cannot be shown in controlled studies. Investigation at the individual patient level may be needed to find patient level risk factors, if that cannot be done on a population level. Another approach that could be of value is to proceed from the genetics perspective. Dr. Colin Marchant, a C.I.S.A. investigator at Boston Medical Center, reported protocols under development to look intensively at other cases and this current case, using both genetics and immunology.

  • Dr. Phil LaRussa, of Columbia University, asked how many cases would be necessary to exceed the background rate. Dr. Iskander replied “nine,”, but added that that would not change the qualitative conclusion.


Update on Isolation of Vaccine-Derived Polioviruses from Five Children in Minnesota

Presenter: Dr. Harry Hull, State Epidemiologist, Minnesota Department of Health


Overview: Minnesota’s response to detection of vaccine-derived polioviruses


An investigation of a poliovirus infection in Minnesota was begun when the state laboratory isolated a vaccine-derived poliovirus from a seven-month-old Amish girl. The child had three healthy siblings, and she had traveled to Wisconsin to visit relatives at age two months. From age five months, she was repeatedly ill with fevers, diarrhea, pneumonia, conjunctivitis, and bronchiolitis. After numerous hospitalizations (attended by her mother and grandmother, who changed her diapers) and outpatient visits, she was admitted at the age of 6 months to a Twin Cities children’s hospital. The child was diagnosed to have severe combined immunodeficiency (SCID), and is scheduled to undergo bone marrow transplantation. Viral culture of her stools was positive for a poliovirus, which was determined to be a vaccine-derived poliovirus (VDPV), with 2.3 percent divergence from the Sabin (vaccine) poliovirus.


Because polioviruses mutate at approximately 1 percent a year, C.D.C. epidemiologists and virologists suspected that the virus may have originated from a child who had received oral poliovirus vaccine (O.P.V.) 2 to 3 years previously. Laboratory data also indicated that this virus has been replicating in at least one other immune-deficient person who was on I.G.I.V. therapy. Because administration of O.P.V. in the U.S. was discontinued in 2000, the originating child must have received it in a country that is still using O.P.V. It appeared to have come from an immunodeficient individual, but how this child was infected remains unclear.


Health Department staff members explored whether there was evidence of transmission within the small Amish community of 24 families in which the index child resided. Door-to-door requests for stool cultures and sera yielded four positive cultures in addition to the index child, among three families. The contact may have occurred in school, where the water supply was inadequate and outhouses were used. Genetic sequencing of the subsequent isolates suggested that the virus had circulated in the community for approximately 2 months.


Thirty-five patients and 23 staff were tracked from the child’s hospitalizations, but cultures were negative. Look-backs at other hospitals she visited detected no other individuals with illness consistent with poliovirus infection. Because the child was already infected on admission to the Children's Hospital, Health Department staff searched for immunosuppressed individuals on the staff of these hospitals or in the medical community, but found no immunosuppressed individuals among healthcare workers. In the Amish community surrounding the index patient,

Some children were rumored to have died in infancy, but that seems not to be unusual in the Amish population. This child was the 29th documented immunocomprised person in the United States to be infected with poliovirus. Most of the other immunocompromised persons were hypogammaglobulinemic and were chronically infected with poliovirus, and some of those were diagnosed only when they developed vaccine-associated paralytic polio (V.A.P.P.).


Control measures. The risk of spread of the VDPV to the general public was felt to be minimal, because 98 percent of Minnesota schoolchildren are vaccinated and therefore presumed to have immunity to polioviruses. This Amish community was receptive to immunization; 53 individuals in nine families were vaccinated, and 14 adults had previously received O.P.V. Both parents of this child had been immunized previously.


Concern remains regarding the possibility of polio transmission within the Amish communities nationwide and abroad. The Amish travel nationally and often gather from across the country (as well as in and from other countries with large Amish populations, e.g. Canada) for special occasions such as large weddings. The Minnesota Health Department is working with local health departments to identify all the Amish communities in seven Minnesota counties and to immunize them. Response has been variable. Some entire communities and schools have volunteered for vaccination; in other communities, only 25 percent to 50 percent of people have been immunized. It was fortunate that the hospital that took the viral culture routinely sends all enteroviruses to the Minnesota State Laboratory for typing; this is not necessarily standard practice across the country.


Dr. Jane Seward reported C.D.C.'s role in coordinating information-sharing across all states in the country and internationally, especially Canada. C.D.C. staff have also been working with the W.H.O. to explore the availability of monovalent O.P.V. for an emergency I.N.D., if needed for an outbreak. CSTE has held two national conference calls to share information, and Health Canada has participated. Dr. Seward outlined the tracking done of the parents and grandparents involved in this case, from Michigan, Wisconsin, and Ontario. Cultures and blood test results are pending. An M.M.W.R. Dispatch was published on October 14 to increase awareness in the states of an increased risk of poliovirus transmission in unvaccinated communities. C.D.C. has called for heightened surveillance for clinically compatible syndromes (for example, acute flaccid paralysis, G.B.S., transverse myelitis), and collection of specimens. Information on EpiX is being updated and PAHO and European nationals have been informed due to transmission risk during travel.


Discussion:

  • If this virus was one of the strains that has circulated in under-vaccinated communities, it would not have the mutation found. Vaccinated individuals can be transiently infected with polioviruses, but they excrete it for very short periods of time at low titers, so a virus circulating in the U.S. for long periods of time seems improbable. O.P.V. may be more effective in halting circulation, but IPV does so as well. None of the five individuals documented as infected have developed paralysis. Nonetheless, the response has been aggressive because the virus is considered to be as virulent and transmissible as a wild poliovirus. It is also the first time a circulating vaccine-derived polio virus has been isolated in an immunodeficient person who had not traveled overseas or been vaccinated overseas. This seven-month-old child had no apparent contact with anyone from abroad, and the virus appears to be of a genetic derivation that arose well before this child was born.

  • Dr. Katz commented that most of the source cases are now vaccine-related, and with jet travel, a person vaccinated in the last 2 to 3 weeks could easily enter the U.S. still shedding the virus. The I.O.M. was planning to discuss this the following week, including whether antivirals could be used in cases such as this.

  • Dr. Seward reported C.D.C.’s close work with the F.D.A. on this child’s treatment. F.D.A. was very helpful in identifying and arranging one-day delivery of an IVIG product with high titer, type 1 polio antibodies.

  • Dr. Halsey commented that all the O.P.V. viruses in the human intestine can revert back to the wild type in terms of neurovirulence, with only a 1 percent divergence from the vaccine type. That is the essential difference from the virus shed by a child vaccinated two weeks earlier. He recommended a detailed 2005 review article on VDPVs (Kew et al, Annu Rev Microbio 59:587-635).

  • N.I.P. is planning a cost analysis of the investigations with all the states involved, to further persuade the public of the benefits of immunization.


PUBLIC COMMENT

Dr. Stan Plotkin warned of a “public health disaster,” which he defined as “when a means of prevention goes unused, owing to a failure of the system to appreciate the seriousness of an endemic or epidemic disease.” The disaster of which he spoke was Lyme disease. His son developed a rash that resolved, but days later he collapsed while walking his dog. The hospital diagnosed Lyme disease.


G.S.K. withdrew its Lyme vaccine, Lymerix, ® after a “tepid A.C.I.P. recommendation” but, he emphasized, the F.D.A. had licensed the vaccine as effective and safe. It was Dr. Plotkin’s opinion that decisions on vaccine use should be based on individuals’ assessment of their own exposure risk to ticks.


The A.C.I.P. recommendation advised that vaccination against Lyme disease should be considered for persons aged 15 to 70 years who engage in activities that result in frequent or prolonged exposure to tick habitats. Vaccination may be considered for persons aged 15 to 70 years exposed to tick-infested habitat but for whom exposure is neither frequent nor prolonged. The benefit of vaccination beyond that provided by basic personal protection and early diagnosis and treatment of infection is uncertain.


In 2004, there were 18,500 cases of Lyme disease in the U.S., at least 4500 in Pennsylvania alone, where some counties have reported rate exceeding 150 per 100,000. Safety problems identified with Lymerix® were being studied by G.S.K., as is done with all new vaccines. Ironically, he noted, there is a commercial Lyme vaccine sold for dogs. He related all this to questions of “life style vaccines.” Vaccination is done for West Nile disease, which causes fewer total cases, and Lyme vaccination compares favorably to the cost-benefit of other vaccines.


Dr. Plotkin suggested that the A.C.I.P. reestablish a Lyme Working Group to solicit interest from manufacturers, or that NVAC be asked to examine this and report back to the A.C.I.P. At least one company is developing a new vaccine, and two companies can produce the old vaccine.


Mr. Peter Khoury, of Baxter Healthcare, reported their development of a chimeric Os-A vaccine to prevent Lyme disease, in collaboration with Stonybrook University and the Brookhaven national labs, which should be in trials in 2006.


Mr. Andrew McNight, of G.S.K., stated that G.S.K. withdrew Lymerix® in 2002 due to poor sales, in part because Lyme disease was not well understood by the public. G.S.K. was proud that their vaccine’s development had advanced public awareness and the science in that regard. Nonetheless, when it was estimated that less than 10,000 people would be vaccinated in 2002, they decided that their resources could be better used elsewhere,


With no further comment, the meeting adjourned at 6:10 p.m., and reconvened on the following morning at 8:00 a.m.


OCTOBER 27, 2005


V.F.C. VOTE ON HEPATITIS A VACCINE

Presenter: Dr. Gregory Wallace, N.I.P.


Changes to be voted on, for the recommendation for routine vaccination with hepatitis A vaccine in the Vaccines for Children program, were as follow:

  • Clarification, by the asterisk under Eligible Groups, that Havrix® and Vaqta® are licensed for persons aged ≥12 months.

  • Clarification, also asterisked, that all children should be vaccinated at one year of age (that is, 12 to 23 months).

  • Routine catch-up or vaccination of those older is not being recommended, but those not vaccinated by age two years can be vaccinated in subsequent visits. Continued routine vaccination of those aged greater than 1 year in areas where it is currently recommended is encouraged.

  • Clarification that the minimum age for vaccination is 12 months.


Dr. Ban Allos moved to approve the V.F.C. resolution as presented. Mr. Beck seconded the motion.

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