M A J O R A R T I C L E
Implementation of Cocooning against Pertussis
in a High-Risk Population
C. Mary Healy,1,2,3Marcia A Rench,1,3and Carol J. Baker1,2,3,4
1Center for Vaccine Awareness and Research Hospital, Texas Children's Hospital;2Ben Taub General Hospital;3Department of Pediatrics and
4Department of Molecular Virology & Microbiology, Baylor College of Medicine, Houston, Texas
acellular pertussis (Tdap) vaccination of all caregivers of infants aged ,1 year (‘‘cocooning’’) to prevent pertussis-
related complications and deaths. We implemented cocooning in a predominantly Hispanic, medically
underserved, uninsured population at a Houston hospital. Phase 1 (January 2008–January 2010) provided
maternal postpartum Tdap vaccine; Phase 2 (June 2009–January 2010) also vaccinated infant contacts on-site.
Methods. Pertussis education was provided to health care personnel and mothers. Standing orders for maternal
postpartum Tdap vaccination were initiated. Mothers were interviewed to ascertain the number of additional infant
contacts eligible to receive Tdap vaccine. Consenting eligible contacts received Tdap vaccine as soon as possible after
Results. From 7 January 2008 through 31 January 2010, 8334 (75%) of 11,174 postpartum women received
Tdap vaccine. During Phase 2, 2969 (86%) of 3455 postpartum women were vaccinated; another 197 (6%) had
previously received Tdap vaccine. Mothers were Hispanic (91.4%), black (5.4%), white (0.8%), Asian (1.4%) and
other (1.0%). A median of 3 (range, 1–11) other Tdap-eligible contacts per infant were identified, and a median of 2
(range, 0–10) contacts per infant received Tdap vaccine. Of 1860 contacts vaccinated, 1813 (98%) anticipated daily
infant contact. A total of 1697 (91%) received Tdap vaccine before infant hospital discharge, and 144 (8%) received
Tdap vaccine within 7 days after hospital discharge. Barriers to full cocooning included the need for extended
vaccination hours, visiting restrictions because of pandemic H1N1 influenza, and inaccurate recall of vaccination
Conclusion. Although practical and logistical barriers exist, Tdap cocooning was well accepted by and
successfully implemented in a high-risk population by using standing orders and providing vaccinations on-site.
In 2006, the Advisory Committee on Immunization Practices recommended tetanus, diphtheria,
Pertussis vaccination in the United States reduced an-
nual pertussis-attributable morbidity and mortality by
92% and 99%, respectively . Despite this fact, and
despite pertussis vaccination rates in US children of
80%–95%, the annual incidence of pertussis has in-
creased since the nadir of 1010 cases reported in 1976
[2, 3]. The Centers for Disease Control and Prevention
(CDC) report that infants under 6 months of age, who
are too young to have completed the primary vaccina-
tion series, have up to a 20-fold higher incidence of
pertussis than does the general population (69.99 versus
3.62 cases per 100,000 population in 2007). Two-thirds
of pertussis-infected infants in this age group are hos-
pitalized . Furthermore, pertussis-related deaths oc-
cur almost exclusively in young infants, the risk being
inversely proportional to age and number of infant
DTaP vaccine doses received [5–7]. Studies also dem-
onstrate that 75% of infants are infected by a household
contact or caregiver, most commonly their mother
(33%) or father (16%) [8, 9]. Pertussis incidence and
mortality are higher in infants of Hispanic ethnicity, for
reasons that are not understood [6, 7, 10].
Since June 2006, in an effort to prevent pertussis in
Practices (ACIP) to the CDC has recommended that
Received 21 May 2010; accepted 31 August 2010.
Presented in part: National Immunization Conference, Atlanta, Georgia, April
19–22, 2010. Abstract # 22776
Correspondence: C. Mary Healy, MD, 1102 Bates St, Ste 1120, Houston, TX
77030, USA (firstname.lastname@example.org).
Clinical Infectious Diseases
? The Author 2011. Published by Oxford University Press on behalf of the Infectious
Diseases Society of America. All rights reserved. For Permissions, please e-mail:
Implementing Cocooning against Pertussis
d CID 2011:52 (15 January)
Tdap vaccine be administered to postpartum women before
hospital discharge and to household and caregiver contacts of
newborns and infants less than 1 year of age . This targeted
vaccination strategy, called cocooning—the only protection
against pertussis available to young infants except vaccination
during pregnancy—has not been widely implemented, largely
because of a lack of necessary infrastructure, a need for education,
a phased implementation of Tdap cocooning in a predominantly
Hispanic, medically underserved, andunderinsuredpopulation in
Houston, Texas. Phase 1 implemented maternal postpartum
vaccination . Phase 2 expanded the program to vaccinate
household contacts of newborn infants on site. This report de-
scribes the implementation of both phases of this strategy through
public hospitals of the tax-supported Harris County Hospital
District in Houston, Texas. Approximately 5000 live-born in-
fants, predominantly Hispanic (.90%), are delivered there
annually. Ben Taub General Hospital cares for a largely un-
derinsured, medically underserved, predominantly Spanish-
speaking population that is likely to have inadequate antenatal
care and is unlikely to receive Tdap vaccine from other sources
or to have knowledge about pertussis or Tdap vaccination
Education for health care professionals (HCPs).
tional methods for HCPs have been previously described .
Briefly, the severity of pertussis illness in young infants and
the rationale for cocooning were presented in obstetrical
grand rounds and small group in-service sessions. In-service
sessions targeted physicians, nurses, administrative staff, and
hospital interpreters. Nursing personnel were particularly
targeted because of their role as trusted advisors for new
mothers and their potential to be powerful vaccine advocates.
In-service sessions occurred at convenient times for day-shift
and night-shift personnel to ensure optimal attendance. Ed-
ucation was performed at regular intervals for new personnel,
to reinforce prior information, and provide updates. Physi-
cian directors and dedicated program nurses also were avail-
able to address any questions from hospital nurses and
Education for postpartum women and families.
advocating Tdap vaccination were displayed prominently in
antenatal, labor and delivery, and postpartum areas. Program
education was incorporated into antenatal, baby-care, and
breastfeeding classes. Each postpartum woman received a per-
tussis information packet that contained bilingual information
about pertussis infection, Tdap vaccination recommendations
Ben Taub General Hospital is 1 of 2
for adults (provided by the Texas Department of Health), and
the Tdap vaccine information statement.
Nurses caring for postpartum women were available to an-
swer questions about the program. This education was supple-
mented, whenever possible, by a visit from our program nurse,
who provided additional education to mothers and any visiting
household contacts or caregivers.
Phase 1: Tdap vaccination for postpartum women.
ginning in January 2008, a standing order for Tdap vaccination
of all eligible and consenting postpartum women was initiated.
Postpartum women were offered Tdap vaccine prior to hospital
discharge unless there was a medical contraindication (eg, his-
tory of anaphylaxis or current unstable neurological condition)
or the woman had previously received Tdap vaccine [11, 15].
During the period from January 2008 through May 2009, a 2-
year minimum interval since receipt of a tetanus-containing
vaccine (tetanus toxoid or tetanus-diphtheria toxoid) was ob-
served . In June 2009, the minimum interval was eliminated
after the CDC issued updated guidelines . Women who
consented received Tdap vaccine on the day of hospital dis-
charge, concomitant withrubella vaccine at a differentsite, if the
latter was indicated. Vaccinated women were given a personal,
updated vaccination record. When Tdap vaccine was not ad-
ministered, hospital nurses documented the reason in the
Phase 2: Tdap vaccination of household contacts.
ning in June 2009, postpartum women were interviewed Mon-
day through Friday by the program nurse to ascertain the
number of household contacts and the number of contacts eli-
gible to receive Tdap vaccine by age and vaccination history.
necessary. Contacts who desired vaccination were referred to
The Cocoon Family Vaccine Center, a dedicated room for the
program on the postpartum floor. Contacts who were unable to
avail themselves of Tdap vaccination prior to maternal hospital
discharge also were referred here by other HCPs and by the
newborn follow-up outpatient clinic.
Tdap vaccine recipients completed a screening questionnaire
adapted from those recommended by the CDC and Immuni-
zation Action Coalition (available at http://www.immunize.org/
catg.d/p4065.pdf). This questionnaire recorded their personal
demographic data and previous tetanus-containing vaccination
history, screened for medical contraindications, and docu-
mented their consent for vaccination. Eligible, consenting con-
tacts received Tdap vaccine as recommended . Each
vaccinated contact was provided with an updated vaccination
record for future use. Tdap vaccination was documented for
Where possible, for each infant, the number of contacts who
received Tdap vaccine was compared with the number of con-
tacts eligible to receive Tdap vaccine. An infant was classified as
d CID 2011:52 (15 January)
d Healy et al.
being completely cocooned when it was confirmed that the
(either through this program or through documentation of
prior Tdap vaccination). Partial cocoons were expressed as
a percentage of vaccinated versus eligible persons.
Identifying barriers. Theprogramwasassessedonaregular
basis to determine Tdap uptake and identify areas for process
improvement. Records were reviewed for demographic charac-
teristics and to define reasons for not administering Tdap vac-
cine. The implementation of Phase 2 coincided with the 2009
H1N1 influenza pandemic, and the hospital instituted visiting
restrictions in late September 2009 through the end of the study
period. Only 1 named contact per postpartum woman was
permitted to visit for the duration of the hospitalization. Other
were not permitted tovisit mother or baby. Tdap vaccine uptake
before initiation of these restrictions was compared with uptake
after restrictions were in place.
Financing could be a barrier to implementing cocooning;
thus, the annual cost to the hospital of delivering this service
(including overhead, personnel, and vaccine costs) was de-
termined. Vaccine cost was determined from price lists available
from the CDC (available at http://www.cdc.gov/vaccines/pro-
grams/vfc/cdc-vac-price-list.htm). The number of Tdap vac-
cine-eligible individuals was calculated by multiplying the
annual hospital birth rate by the median number of eligible
persons per newborn, as determined by maternal interview.
Statistical analysis was performed using SPSS software, ver-
sion 15.0 for Windows (SPSS). Statistical significance for di-
chotomous outcomes was determined by v2and Fisher exact
tests. Normally distributed data were assessed by means and the
Student’s t test; where positive or negative skewing of data oc-
curred, statistical significance was assessed by medians and the
Mann-Whitney U test.
Phase 1: Tdap vaccination of postpartum women.
hundred and fifty HCPs completed in-service training, which
was repeated at regular intervals. From 7 January 2008 through
31 January 2010, 8334 (75%) of 11,174 postpartum women
(medianage,27years;range, 11–47 years)receivedTdapvaccine
prior to hospital discharge. No serious adverse events were re-
From 1 June 2009 through 31 January 2010, following elim-
ination of the requirement for a 2-year minimum interval since
receipt of prior tetanus-containing vaccine , 2969 (86%) of
3455 postpartum women received Tdap vaccine prior to dis-
chargefrom the hospital(91%of those whoreported themselves
eligible). An additional 197 (6%) had documented prior Tdap
vaccination; 172 of these had been vaccinated by our program
following the birth of a previous infant. Vaccinated women
during this interval had demographic characteristics that were
similar to those of the overall cohort. Two-hundred and ninety-
two (10%) were <19 years of age. Women who had received
Tdap vaccine during the current hospitalization or previously
did not differ by age, but they did differ by ethnicity, when
compared with women who had not received Tdap vaccine. The
proportions of white and black women who refused Tdap vac-
cine were 3.1-fold and 2.1-fold greater, respectively, than those
who did not (P , .001) (Table 1).
Phase 2: Tdap vaccination of household contacts and
caregivers. Sixty-seven percent of postpartum women (2303
of 3445) were interviewed by the program nurse. Most women
who were not interviewed delivered their infants and were dis-
charged from the hospital on days on which the program nurse
was not present (generally on the weekend). Maternal interviews
identified that families had a median of 4 household contacts
(range, 1–15 contacts), of whom a median of 3 contacts (range,
64 years; no prior Tdap vaccine; no medical contraindications).
The median number of vaccinated contacts was 2 (range, 0–10
contacts). Overall, 1332 (58%) of the families of interviewed
mothers had >1 household contact (other than the mother)
vaccinated with Tdap by this program.
The characteristics of 1860 infant contacts who received Tdap
vaccine are summarized in Table 2. A total of 1697 (91%) were
Vaccinated with Tetanus, Diphtheria, Acellular Pertussis (Tdap)
Vaccine at Hospital Discharge from 1 June 2009 through 31
Characteristics of Women Vaccinated and Not
No. (%) of women
(n 5 3166)
(n 5 279)
Hispanic 2891 (91.3)228 (81.7)
Black 167 (5.3) 31 (11)
Asian 47 (1.5)5 (1.8)
White 27 (.8)7 (2.5)
Other34 (1.1) 8 (2.8)
10–19 Years 314 (9.9)32 (11.5)
20–24 Years 738 (23.3)65 (23.3)
25–29 Years918 (29) 71 (25.4)
30–34 Years 858 (27.1)75 (26.9)
249 (7.9)25 (9)
89 (2.8) 11 (3.9)
after 1 June 2009.
No minimum interval since previous tetanus-containing vaccine
aA total of 2969 individuals received Tdap vaccine between 1 June 2009
and 31 January 2010; 197 had previously received Tdap vaccine
bP , .001.
Implementing Cocooning against Pertussis
d CID 2011:52 (15 January)
vaccinated before or on the day of infant discharge from the
hospital; an additional 144 (8%) were vaccinated on days 1–7
after infant hospital discharge. A total of 1813 contacts (98%)
reported daily contact with the infant, and 63% anticipated that
contact would exceed 12 h per day. One-thousand and eighteen
(55%) could not remember when their last tetanus-containing
vaccine was administered, even to within a 5-year interval. One
patient reported feeling ill 48 h after Tdap vaccine administra-
tion; this was deemed to be unrelated to Tdap vaccination after
the patient received a diagnosis of gastroenteritis from her
Pertussis vaccination histories for each contact were obtained
for 2268 (99%) of 2303 families. Following this program,
a complete cocoon (vaccination of 100% of infant contacts)
was achieved for 579 (26%) of the infants. Overall, the
median percentage of each cocoon completed was 50% (range,
Effect of the H1N1 pandemic.
hospital visiting restrictions during the H1N1 pandemic, Tdap
vaccination rates decreased. Among interviewed families, the
proportion of fathers vaccinated decreased from 58% to 49%
(P , .001); families with >1 contact (other than the mother)
vaccinated decreased from 64% to 53% (P , .001), and the
proportion of families with a completed cocoon decreased from
28% to 23% (P , .001). The Tdap vaccine uptake rate among
Following the institution of
postpartum women increased from 89% to 94% during the
same time period (P 5 .002).
Estimate of annual cost. We estimated the cost per dose of
Tdap vaccine administered as $40, considering the CDC con-
tract cost per dose ($26.25) plus the cost of overhead, faculty,
and nursing personnel required to administer the program.
Assuming an annual birth rate of 5000 babies and 4 persons
(mother and 3 Tdap vaccine–eligible contacts) vaccinated to
complete a cocoon, the annual cost of this program was esti-
mated at approximately $800 000.
implementation of pertussis cocooning in a US hospital setting
in a population at particular risk of transmitting life-threatening
pertussis to young infants [3, 4, 7–10, 17]. Cocooning is difficult
to implement [12–14, 18, 19]. Cocooning involves a new vac-
cination platform utilizing health care providers who may be
relatively unfamiliar with the severity of pertussis illness in
young infants and who, traditionally, have not provided vacci-
nations. It targets 2 populations, postpartum women and the
contacts of newborn infants until 1 year of age, who have dif-
ferent educational needs and are governed by different state and
legal requirements regarding vaccinations. Finally, there are
significant financial constraints for hospitals and physicians.
We achieved overall Tdap vaccination rates in excess of 90%
infect young infants [8, 9, 15, 20]. Eliminating the minimum 2-
year interval since receipt of prior tetanus-containing vaccine is
the most important explanation for this increase from our
previously reported 72% vaccination rate . Our cohort has
little access to health care outside of childhood and peripartum
periods and is more likely to receive recommended tetanus-
diphtheria toxoids (Td) booster vaccine during pregnancy,
precluding them from receiving postpartum Tdap vaccine in
prior years. This was exacerbated by inaccurate reports of Td
vaccine receipt when other intramuscular agents were admin-
istered during pregnancy . It also is likely that repeated
education targeting HCPs, coupled with their increasing famil-
iarity with the rationale for cocooning, enhanced their role as
vaccination advocates. However, although postpartum vaccina-
tion is a necessary prerequisite for the ‘‘protective cocoon’’
around a newborn infant, it alone is unlikely to reduce infant
infection rates by more than a third, if that [8, 9, 15]. Further-
more, the 14-day window required to develop a ‘‘protective’’
with subsequent infant transmission. The most significant limi-
tation of focusing only on postpartum women is that household
contacts also may infect infants [6, 8, 9, 20–23], especially in
populations where large households are the rule.
Tetanus, Diphtheria, Acellular Pertussis (Tdap) Vaccine
Characteristics of 1860 Contacts Vaccinated with
Age, median years (range)30 (11–64)
Hispanic 1757 (94.5)
Black 47 (2.5)
Other 5 (.2)
Relationship to infant
Sibling 54 (3)
Uncle 119 (6.4)
Great-grandparent 4 (.2)
Caregiver 43 (2.3)
Data are no. (%) of contacts, unless otherwise indicated.
d CID 2011:52 (15 January)
d Healy et al.
Establishing a platform to vaccinate family and household
contacts is particularly challenging. Ideally, this platform
should deliver the service prior to the infant’s birth, thus al-
lowing time for protective immunity to develop before the
infant’s birth. In practice, this is unlikely to occur, given that
preventative services often are not a priority for healthy
adults. Delivering a service before the infant’s discharge from
hospital is a reasonable, if imperfect, compromise that will
theoretically provide indirect protection to infants by age 14
days. A hospital-based program is likely to be superior to
models that target pediatrician offices because it can vaccinate
and protect contacts earlier. A hospital-based program also
can theoretically immunize larger, more-diverse populations
of contacts who may be more likely to visit the hospital than to
attend well-child visits, and it provides a service for contacts
before the demands of caring for a newborn infant take
priority after hospital discharge .
A hospital program is subject to significant barriers, however.
There are state-specific legal and logistical complexities when
vaccinating individualswhoare nothospital patients.There isthe
need to provide service during times when working families are
visiting (eg, evenings and weekends). We achieved a remarkably
was particularly effective for families who visited during cocoon
clinic operating hours, compared with families who received
clinic referrals. We have recently expanded our service, adding an
additional program nurse on weekends to overcome this limi-
tation; however, this increases program cost considerably.
Our program highlights some inherent limitations of current
vaccination platforms and future cocooning strategies. We
vaccinated significant numbers of adolescents, who are epide-
miologically at high risk of transmitting pertussis but are more
properly targeted by the adolescent platform [20, 24–26]. Fur-
thermore, this age group, for whom school mandates have been
established, is not affected by vaccine procurement costs, as
older age groups are, because cost is covered by the Vaccines for
Children program. The need for access to lifespan vaccination
registriesisalsohighlighted, because recallofvaccination history
is notoriously unreliable. This will assume greater importance if
recommendations for Tdap booster doses are made. The cost of
Tdap vaccine procurement and administration is often viewed
as prohibitive for hospitals and physicians, because this has not
yet been bundled into maternity charges covered by Medicaid or
by many insurance plans.
One attraction of a cocooning delivery model is the potential
to immunize against infections that target very young infants in
cases in which infant vaccination is not appropriate (eg, in-
fluenza). Our finding that the Tdap vaccine uptake rate among
postpartum women increased during the 2009 H1N1 influenza
pandemic, probably attributable in part to greater awareness of
vaccinations in general, suggests that this approach could have
synergy in preventing both infections. Ironically, the pandemic
also negatively impacted our ability to cocoon against pertussis
when infection control measures eliminated the very motivation
(ie, visit to mother and infant) that allowed us to vaccinate
a diverse group of household contacts.
Our study has some limitations. First, despite our best efforts
to verify vaccination history, inaccurate reports of prior Tdap
vaccination may have reduced our vaccination rates. However,
program nurses were very proactive and administered Tdap
vaccine when the vaccination history seemed doubtful, realizing
that the benefit to contacts and infants exceeded the risk of
greater injection site reactions. Second, we could have under-
estimated the number of cocoons completed, because additional
contacts may have accessed no-cost or low-cost vaccines
through public health clinics, as noted in our educational ma-
terials, especially during times when H1N1 vaccine also was
available. Finally, publicity surrounding the importance of
vaccinations that accompanied the 2009 H1N1 pandemic could
have positively affected our cohort’sacceptance of Tdap vaccine,
although high acceptance rates have previously been reported in
this population .
Cocooning alone is unlikely to completely prevent infant
pertussis-related deaths, because the infant is vulnerable in the
first few weeks of life. Augmenting cocooning with maternal
vaccination in the third trimester of pregnancy could offer greater
benefit. This approach was shown to be safe and effective with
whole-cell vaccines many decades ago [27, 28]. Contemporary
studies have demonstrated that pertussis antibodies are actively
transported from mother to infant, the half-life of this antibody
has been calculated, and high maternal antibodies did not in-
Maternal vaccination could be a potent weapon in reducing
pertussis-related mortality and morbidity in early infancy, while
allowing more time for vaccination of other contacts.
In summary, our study demonstrates that, although it is
possible to achieve high Tdap vaccination rates for hospital-
based cocooning, such a program requires a significant in-
vestment of resources to achieve its goals. In addition to the
costs and hospital HCP support outlined, our program uti-
lizes the services of 2 physicians, 2 full-time program nurses,
and administrative support that is not reimbursed by the
hospital. Targeted educational initiatives need to be delivered
and updated frequently to meet the specific needs of the target
population. Ideally, the service should be delivered either
before or as soon as possible after birth and not restricted to
8 am to 5 pm on Monday through Friday, but scheduled for
the convenience of working contacts. A variety of vaccination
providers should be used. It is only through the investment of
time and finances and by using innovative models in a co-
Implementing Cocooning against Pertussis
d CID 2011:52 (15 January)
operative fashion that a successful infant cocoon program can
Fund and Children’s Health Fund of the Harris County Hospital District
Foundation, for funding to establish and run this program; Sanofi Pasteur,
for donating Tdap vaccine; Kenneth Mattox, Harold Miller, Amy Young,
Joseph Garcia-Prats, Lori Sielski, Rachelle Nurse, and Frances Kelly (Ben
Taub General Hospital, Houston, TX), for their assistance in establishing
and ongoing support for this program; Betsy H. Mayes and Nancy Ng
(Center for Vaccine Awareness and Research, Texas Children’s Hospital,
Houston, TX) and Carolyn Fairchild (Coordinator of Data Informatics for
Women and Infants, Ben Taub General Hospital, Houston, TX), for as-
sistance in data collection; and Robin Schroeder (Baylor College of Medi-
cine, Houston, TX), for assistance in preparing this manuscript.
Potential conflicts of interest. Tdap vaccine was donated by Sanofi
Pasteur. C.M.H. receives a research grant from Sanofi Pasteur and has
served as on an advisory board for Novartis Vaccines. All other authors: no
Wethank theBaylorMethodistCommunity Health
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