Vaccinations in adulthood play an important role in public health and in reducing the morbidity and mortality associated with infections.
Abstract: Many adult patients have not received recommended vaccines. The pharmacist is in a unique position to participate fully in the Standards for Adult Immunization Practice’s standards of assessment, recommendation, administration, and documentation of adult vaccines. This article reviews the Standards for Adult Immunization Practice and the Centers for Disease Control and Prevention’s 2017 Adult Immunization Recommendations to help pharmacists play an active role in improving immunization rates in their community.
Adult vaccinations are one method of decreasing infections and their associated morbidity and mortality. The United States has created goals for specific health characteristics, including vaccine-preventable illnesses and immunizations. HealthyPeople 2020 was established in 2008 with specific standards it hopes to achieve by 2020.1 Many of the goals have not yet been achieved.
One important HealthyPeople goal is to decrease the incidence of invasive pneumococcal disease (IPD) in the elderly and high-risk populations. Consider, for example, the noninstitutionalized elderly. In this population, although the goal of decreasing IPD to 31 per 100,000 overall has been met, the target of 9 per 100,000 for antibiotic-resistant IPD remains elusive (12.2 per 100,000 in 2008 to 10.2 per 100,000 in 2013).1 This lack of significant improvement in antibiotic-resistant IPD is likely at least partially due to the very low pneumococcal vaccination rates in the elderly. Specifically, although goal vaccination is 90%, only 60% of this population is vaccinated, and no significant improvements have been made in recent years.1,2 Pneumococcal vaccination also lags for high-risk patients 18 to 64 years of age (goal: 60%). Despite small gains, only 20% of this group was vaccinated in 2014.1,2
Most recent estimates suggest that the annual incidence of IPD is down to a low of about 30,000, with 3,000 related deaths.3 It is believed that the improvements in IPD and pneumococcal mortality are likely multifactorial. First, pediatric 13-valent pneumococcal conjugate vaccine (PCV13) uptake is high, and this may reduce the carriage of vaccine-associated strains resulting in disease among nonvaccinated patients. Second, the Advisory Committee on Immunization Practices (ACIP) has recently recommended both the PCV13 and the 23-valent pneumococcal polysaccharide vaccine (PPSV23) for high-risk patients, as well as for all patients 65 years and older. This addition of PCV13 to the recommendations may have provided some modest improvements seen in vaccination rates in these age groups.4 Finally, the impact of pharmacists on vaccinations and the recent expansion in their ability to provide broad immunizations in many states will likely demonstrate significant impact in the coming years.5,6
Unfortunately, this phenomenon is not limited to pneumococcal vaccination. Adults are often behind in many vaccinations. Common examples include: influenza and tetanus vaccine in the general population, zoster vaccine in the elderly, and pertussis vaccine in expectant mothers.1,2,7 Influenza vaccination goals for general adults, expectant mothers, and elderly are 70%, 80%, and 90%, respectively. Most recent reports suggest that only 32% of young adults, 48% of middle-aged adults, 28% of expectant mothers, and 67% of elderly have received an influenza vaccination.1,2
Up next: Improving vaccination in the community
Improving vaccination in the community
In an effort to improve adult vaccinations, the National Vaccine Advisory Committee (NVAC) has published Standards for Adult Immunization Practice.8 These practice standards, most recently updated in 2014, recommend that all health-care providers (including pharmacists) assess, recommend, administer, and document adult immunizations.
The updated standards recognize that pharmacists have proven to be an integral partner to improving adult vaccination rates and that all health-care providers, even those who do not administer vaccines, should routinely assess and provide recommendations for adult vaccinations.8
Although pharmacists have demonstrated improvements in adult vaccine administration, recent survey data suggest that pharmacists are among the least likely to routinely assess adult patients for vaccination.9 This low rate of active assessment is likely partially due to a lack of awareness about the practice standards and, to a certain degree, related to the difference in the patient encounter in the community pharmacy. Specifically, patient encounters with pharmacists are not scheduled, nor does a pharmacist use an elaborate intake form. These differences make it more difficult for community pharmacists to easily routinely assess for needed vaccinations. To take a more active role in improving vaccination rates of adults in the community, pharmacists will need to be involved in all parts of the standards.
The first step of the Adult Immunization Practice Standards is patient vaccination assessment, which recommends that adult patients be screened at each encounter to determine if vaccinations are needed based on current vaccination standards.8 It also recommends that health-care providers, including pharmacists, have protocols and policies in place to ensure that this screening occurs as part of standard practice (see Table 1 for resources).8 Current vaccination recommendations for adults are discussed in this article.
For pharmacists in the community to participate routinely in the assessment standard, a mechanism is needed to incorporate this vaccine assessment into their routine workflow. One mechanism could be to have pharmacists perform the assessment and take notes when conducting the initial medication review. Alternatively, a pharmacy technician can assist the pharmacist in having patients complete questionnaires to help identify which vaccines are due for them. Either way, the pharmacist should identify immunizations needs based on the patient’s age and conditions. If a patient has already left the pharmacy, the pharmacist or technician can tag the prescription and have that patient speak with the pharmacist when they come to pick up their prescription. Table 1 provides other resources that pharmacists can employ to improve vaccination assessment, such as the use of a premade patient immunization intake form from the CDC or the placement of educational posters throughout the pharmacy to remind staff to assess patients.
The second part of the Adult Immunization Practice Standards advises that the provider go beyond identifying what vaccines the patient is recommended to receive and begin to provide a strong patient-specific recommendation. When providing the recommendation, the pharmacist should explain the vaccine to the patient and address any questions the patient may have.8 The CDC also provides forms to document what vaccines are recommended that can be completed for individual patients (Table 1).
The third part of the standards recommend administration of the vaccines or referral of the patient to an appropriate provider when necessary.8 This is also important for the pharmacist, as not all pharmacists provide every vaccine. Pharmacists should become aware of other vaccine providers in the area that provide vaccines they cannot obtain and/or provide. HealthMap (Vaccinefinder.org) has an online tool that pharmacists can use to ensure their pharmacies are included as locations that provide specific vaccines, and to use as a tool to identify other providers to whom they can refer patients as needed for other specific vaccines they do provide (Table 1). In addition to providing the referral, it is recommended that the pharmacist determine whether that the patient has received the recommended vaccine at the next encounter.8 It is also important for the pharmacist to ensure that vaccines are stored appropriately and administered per current recommendations (Table 2).
Finally, the standards recommend that the pharmacist document vaccine administration via the state’s immunization registry (if available), as well as in the patient’s medical record. It is also recommended that pharmacists document and inform the patient’s other health-care providers about the vaccination.8
The CDC provides annually updated recommendations for adult patients 19 years and older in Morbidity and Mortality Weekly Report. The update published in February 2017 was supported by the American College of Physicians, the American Academy of Family Physicians, the American College of Obstetricians and Gynecologists, and the American College of Nurse-Midwives (Table 1).10 This schedule provides a good overview of what is needed for adult age groups, including young and middle-aged adults, and the elderly. Additionally, the recommendations summarize vaccines recommended by indication or medical condition. Patients usually need the age-specific vaccines as described here plus additional ones for their conditions. Briefly, these recommendations are summarized in Table 3.10 It is also very important for the pharmacist to become familiar with the schedule and its annual changes to be able to assess, recommend, and administer vaccines as recommended by the CDC and the NVAC in the Standards for Adult Immunization Practice.8,10
ACIP, the recommendation committee for immunization, has been in existence for about 50 years: the first vaccines were recommended in 1965.11 Immunization recommendations change each year, and many vaccines are relatively recent additions.10 This is a very important concept for the pharmacist to understand, as many patients know they received vaccines in childhood, but many vaccines may not have been available or recommended for these adults in their childhood. Therefore, the pharmacist should gain a general understanding of when vaccines were first recommended by the CDC.
In 1965, measles and influenza (and smallpox) were the first recommended vaccines in the US. These were soon followed by poliovirus (1967); mumps (1968); rubella (1969); measles, mumps, and rubella (MMR, 1971); and diphtheria, tetanus, and whole-cell pertussis (1971) vaccinations.11 By the late 1970s and early-middle 1980s, PPSV23, meningococcal polysaccharide, hepatitis B, and Haemophilus influenzae type B vaccines were approved and recommended. Varicella and hepatitis A vaccines came in the late 1990s, followed by human papillomavirus (HPV); tetanus, diphtheria, pertussis (Tdap) for adults; zoster; quadrivalent meningococcal conjugate (MCV); and PCV13 vaccines in the mid-2000s and later.11 The next sections of this review focus on key immunization recommendations for the various age groups throughout the adult lifespan.
Patient vaccination assessment
When assessing for vaccination, it is important to determine a patient’s full vaccination history when available. Some vaccines such as MMR and varicella are often completed in childhood and only needed for adults if their childhood vaccinations were missed.10–13 Other vaccines such as Tdap require the primary series on first administration of the vaccine regardless of age of first receipt, but then require booster doses throughout the adult lifespan. Although beyond the scope of this discussion, it is important to also consider additional vaccinations that may be indicated due to high-risk conditions in patients. Depending on age, these may include hepatitis A, hepatitis B, pneumococcal, or meningococcal vaccinations.10
Contraindications must be ruled out before completing your patient immunization assessment. Any severe reaction to a prior dose or something included in the vaccine, such as an excipient, is a contraindication to future doses of that vaccine.9 Other types of reactions or possible contraindications should be reviewed to determine if these are contraindications or not. Similarly, if patients have moderate or severe illness, it is often best to wait until the patient’s illness improves before providing the vaccine. After that, it is often easiest to consider whether the potentially recommended vaccines are live or inactivated, because live vaccines are contraindicated in pregnant women and in most immunocompromised patients (Table 2).10–15
Specifics on vaccination of immunocompromised patients are beyond the scope of this article, but these have been summarized by the CDC in the indications table of the annual immunization recommendations, and have been published by the Infectious Diseases Society of America.10,15
Immunizations recommended for young adults
Annual influenza vaccination is routinely recommended for young adults ages 19 through 26 years.10 These patients should also be routinely assessed to ensure they are up-to-date on Tdap, MMR, varicella, and HPV.10 In addition, meningococcal vaccination may also be indicated for these patients.10
There are currently two types of tetanus and diphtheria-containing vaccines, one with pertussis antigens (Tdap) and one without (Td). Tdap is the only adult vaccine that contains pertussis antigen. Patients who have not received a primary series of tetanus-containing vaccines (often in childhood) will require a three-dose primary vaccination series in which one dose contains pertussis antigen. A dose of Tdap is indicated for adults who have received the primary series but who have not received a Tdap dose: the same is true when there is uncertainty about whether the patient received a pertussis-containing vaccine.10
Additionally, a tetanus and diphtheria-containing booster vaccine is recommended for adult patients every 10 years.10 The booster should contain pertussis antigen if the patient has not yet received a dose of Tdap. Otherwise, the patient should receive a dose of Td. Finally, booster doses as soon as 5 years after the last tetanus-containing vaccine are recommended for patients with tetanus-prone wounds.10
Although MMR vaccination should be completed in childhood, many adults may be unvaccinated or under-vaccinated for this vaccine. Healthy adults who are attending post-high school educational institutions, traveling internationally, or are health-care personnel should have had two doses of the MMR vaccine, separated by 28 days.10,12 All other adults are recommended by the CDC to have a single lifetime dose of MMR vaccination.10,12
Varicella vaccination is also an important vaccine that many young adults may need. To be considered immune to varicella, young adults would require evidence of two doses of vaccination (4–8 weeks apart), laboratory evidence of verification of disease, or diagnosis of having either chickenpox or zoster by a health-care provider.10
Up until 2007, only one dose of the varicella vaccine was recommended if given during childhood. In 2007, two doses of varicella vaccination were recommended for all patients, because one study noted a 3.3-fold lower frequency of breakthrough infection in children who received two doses of the vaccine.13 Since the implementation of a two-dose varicella vaccination for all, the incidence of varicella has declined by 72% and varicella-related hospitalizations have declined by 38%.16 The number, size, and duration of outbreaks have also decreased since the implementation of the two-dose recommendation (2007 to 2010).16 Therefore, it is important to continue to identify not only those patients who may be unvaccinated but also those who are under-vaccinated (i.e., received one but not both doses). When assessing patients, remember that if patients have received a single dose of the vaccine, they do not need to restart the vaccination. The second dose can be given at any time after 4 to 8 weeks.10,13
Young adults should also be assessed for immunity to HPV. Catch-up vaccination is recommended for women and high-risk men through age 26 as well as for non-high-risk men through age 21 years.10,17 Patients are considered high-risk if they are immunocompromised (by disease or medication) or are men who have had sex with men. When assessing patients, note that the recommendation for this age is a three-dose series given at 0, 2, and 6 months.10 The CDC recently approved a two-dose series for non-high-risk adolescents if they begin vaccination before age 15 years. The CDC recommends considering these patients fully immunized if they began their vaccine series prior to age 15, are not immune-suppressed, and if two doses were administered at least 5 months apart.10,18 Another important consideration is that the 9-valent vaccine is currently the only HPV vaccine available in the United States. The CDC has clarified that patients begun on another HPV vaccine can finish their vaccination (not restart) with this version.10,17
Although not clearly obvious from the adult schedule, meningococcal vaccination is something that is routinely indicated in some young adults. Specifically, college freshmen living in dorms are at increased risk of meningococcal disease if they did not receive a dose of meningococcal ACWY (MenACWY) at age 16 and if they are currently younger than 21.10 Additionally, young adults, age 23 or younger who did not complete a meningococcal type B vaccination may receive a meningococcal type B vaccine series. Healthy patients during non-outbreak situations should receive a two-dose series with either vaccine.10
Immunizations for women planning pregnancy and their families
Vaccinations are also important for women who are planning pregnancy as well as those who are pregnant. It is important to ensure that patients who are planning pregnancies are up-to-date on their vaccinations, and to make sure they have received any live-virus vaccinations they may need.10 Women of childbearing age as well are considered a group that should be focused on for both MMR and varicella vaccinations. These live vaccines should be administered at least 28 days prior to becoming pregnant.10
Once your patient is pregnant, there are additional vaccines that are very important to help protect her and/or the baby. Vaccination priorities for all patients during pregnancy include influenza and pertussis vaccination. Pregnant patients should receive an age-appropriate inactivated influenza vaccine during influenza season (generally August through April or May).10 The influenza vaccine helps protect a pregnant woman, who is at increased likelihood for severe influenza, because pregnancy is believed to not only impair breathing due to physical changes but also cellular immunity. Further, the vaccine may help prevent in utero complications and preterm delivery, as well as help prevent the infant from having influenza-like illness or being hospitalized with influenza in the first 6 months of life, before the infant can be vaccinated.19
Pertussis vaccination is also very important to protect the infant. It is recommended that pregnant patients receive a dose of Tdap between 27 and 36 weeks-and earlier (e.g., 27–29 weeks) if possible.10 This vaccine should be administered during every pregnancy, regardless of prior vaccination status.10,20 Providing pertussis vaccination to the pregnant patient is necessary because studies have shown that maternal pertussis vaccination protects infants in the first few months of life when they are at highest risk for severe disease and are too young to be vaccinated.10,20–22
It is not just the pregnant woman who needs to worry about vaccinations. Vaccinations are recommended to ensure that families and patients who are caring for young infants are up to date on their vaccines, with a specific focus on influenza, pertussis, and varicella vaccines.10,19,23
Immunizations for middle-aged adults
Immunizations for middle-aged adults–those age 27 years through 59 years for the purposes of vaccination recommendations–are similar in many respects to those for young adults. Middle-aged patients also should be evaluated to ensure they have received recommended doses of influenza, Td/Tdap, MMR, and varicella vaccinations.10
This age group does have some unique considerations in regard to the varicella vaccine. These patients should be assessed for immunity as previously discussed, although those born in the United States before 1980 can be considered immune based on age alone, unless they are planning a pregnancy or are a health-care provider, because varicella was endemic prior to routine vaccination.10,13
Immunizations for those age 60 years and older
Patients who are age 60 years and older should continue to be assessed for immunity to influenza and Td/Tdap. Because they are born before 1957, however, they can be considered immune to diseases covered by the MMR vaccine.10 In addition to the vaccines that have been recommended in younger adult patients, these older adults should now also be assessed to determine their vaccination status for herpes zoster and pneumococcal disease.10
The CDC recommends that patients should receive a single dose of the herpes zoster vaccine beginning at age 60 years.10,24 It is important to understand the pathophysiology of herpes zoster infection, however, as it is different from most other vaccine-preventable diseases. In herpes zoster infections, the patient is not acutely infected with the virus but was infected with varicella zoster virus earlier in life-often in childhood. The virus is suppressed by the patient’s immune system until a time when the patient’s cellular immunity wanes and his or her immune system no longer effectively suppresses the virus. The virus then spreads along the nerve cells to the skin, resulting in herpes zoster infection. The herpes zoster vaccine is a live antigen, the goal of which is to stimulate the immune system to continue to suppress the zoster virus.25 The CDC recommends vaccination at this age to provide the highest likelihood of protection when the risk of herpes zoster disease and complications are greatest.
Short- and long-term persistence studies evaluating the continued efficacy of the zoster vaccine have shown strong reductions in burden of illness of 75% at 5 years, 33% at 10 years, and no longer statistically different than placebo at 11 years.26 Therefore, it is generally not recommended to provide the vaccine to those under age 60 years, because it increases the likelihood that the vaccine efficacy can wane before the age at which the risk is greatest.24
Pneumococcal vaccination is also very important for older patients. IPD and death related to pneumococcal disease are highest in patients older than age 65 years.4 Although not specifically monitored, the incidence of pneumococcal community-acquired pneumonia is high in this age group.
Currently, two vaccines are routinely recommended for patients age 65 years and older. These vaccines are the PCV13 and the PPSV23. Neither vaccine alone is sufficient. The PCV13 is expected to have an additional effect on reducing IPD, but it is also expected to prevent thousands of cases of community-acquired pneumonia each year. It should not be relied on alone, however, because almost 40% of all cases of IPDs are caused by strains only included in the PPSV23.27 It is also important for the pharmacist to understand the order of vaccines. For patients who have not received either vaccine, the PCV13 vaccine is recommended to be administered first, as it will result in an overall stronger antibody response.27 The two vaccines should be separated by one year in otherwise healthy patients, or eight weeks if patients have a cochlear implant, CSF leak, or an immunocompromising condition (e.g., asplenia, cancer, or medications).28
Unfortunately, even after reviewing the latest guidelines and providing patients an appropriate vaccine assessment and recommendations, many patients may be hesitant to get vaccinations. Vaccine hesitancy is a new area of research. Currently, it is understood that vaccine hesitancy represents a continuum ranging from all-out vaccine refusal, to accepting some vaccines and not others, to accepting them all at a delayed schedule or just being doubtful.29 Multiple sources suggest that the success of vaccinations as well as the number of vaccines recommended makes more patients less likely to
understand their importance.29–31 Limited data suggest that multiple interventions are often needed, including: focusing on patients who are under- or unvaccinated, providing patients with education regarding diseases and vaccines including both benefits and risks, improving convenient access to vaccines, and providing patients with reminders to get their vaccines.29–31
Data suggest that it is not just the information that is important, but how the information is delivered. One source recommends that discussions occur with the patient away from computers and other distractors.32 Additionally, general statements are not as helpful as evidence-based resources and responses to patient’s questions. The CDC’s adult vaccine educational resources are helpful for these discussions (Table 1).
Pharmacists are in a unique position as health-care providers who are able to interact with patients frequently and provide convenient access to vaccinations. We can help our patients by taking an active role in not only administering vaccines, but also providing an assessment and patient-specific recommendation for needed vaccinations. Most patients should be assessed for influenza, Td/Tdap, and MMR vaccines. Young adults often are behind on HPV vaccination and so should be assessed for it, whereas adults older than age 60 years should be assessed for pneumococcal and zoster vaccinations. Pharmacists who review patient information to actively assess and recommend vaccines based on the patient’s age have the potential to make significant inroads in addressing under-vaccination of adults. It is also important for pharmacists to use skill in talking with patients to understand and manage any vaccine hesitancy that patients may express.
1. Healthy People 2020. Immunization and Infectious Diseases Data Details. U.S. Department of Health and Human Services, Office of Disease Prevention and Health Promotion. https://www.healthypeople.gov/node/3527/data-details. Accessed April 11, 2017.
2. Williams WW, Lu PJ, O’Halloran A, et al: Centers for Disease Control and Prevention (CDC). Surveillance of vaccination coverage among adult populations–United States, 2014. MMWR Surveill Summ. 2016;65(1):1–36.
3. Centers for Disease Control and Prevention. Pneumococcal disease. Surveillance and reporting. Updated June 21, 2016. https://www.cdc.gov/pneumococcal/surveillance.html. Accessed April 11, 2017.
4. Centers for Disease Control and Prevention. Active Bacterial Core surveillance (ABCs). Surveillance Reports. Updated April 5, 2017. https://www.cdc.gov/abcs/reports-findings/surv-reports.html. Accessed April 11, 2017.
5. Isenor JE, Edwards NT, Alia TA, et al. Impact of pharmacists as immunizers on vaccination rates: a systematic review and meta-analysis. Vaccine. 2016;34(47):5708–5723.
6. Baroy J, Chung D, Frisch R, et al. The impact of pharmacist immunization programs on adult immunization rates: a systematic review and meta-analysis. J Am Pharm Assoc (2003). 2016;56(4):418–426.
7. Barber A, Muscoplat MH, Fedorowicz A. Coverage with tetanus, diphtheria, and acellular pertussis vaccine and influenza vaccine among pregnant women-Minneota, March 2013–December 2014. MMWR Morb Mortal Wkly Rep. 2017;66(2):56–59.
8. National Vaccine Advisory Committee. Recommendations from the National Vaccine Advisory committee: standards for adult immunization practice. Public Health Rep. 2014;129(2):115–123.
9. Bridges CB. National Center for Immunization & Respiratory Diseases. Impact of Adult Immunization. https://www.acponline.org/system/files/documents/about_acp/chapters/wi/16mtg/bridges.pdf. Accessed April 11, 2017.
10. Kim DK, Riley LE, Harriman KH, et al. Advisory Committee on Immunization Practices Recommended Immunization Schedule for Adults Aged 19 Years or Older–United States, 2017. MMWR Morb Mortal Wkly Rep. 2017;66(5):136–138.
11. Walton LR, Orenstein WA, Pickering LK. The history of the United States Advisory Committee on Immunization Practices (ACIP). Vaccine. 2015;33(3):405–414.
12. McLean HQ, Fiebelkorn AP, Temte JF, Wallace GS; Centers for Disease Control and Prevention. Prevention of measles, rubella, congenital rubella syndrome, and mumps, 2013: summary recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 2013;62(RR-04):1–34.
13. Marin M, Guris D, Chaves SS, et al; Advisory Committee on Immunization Practices, Centers for Disease Control and Prevention (CDC). Prevention of varicella: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 2007;56(RR-4):1–40.
14. Rubin LG, Levin MJ, Ljungman P, et al. 2013 IDSA clinical practice guideline for vaccination of the immunocompromised host. Clin Infect Dis. 2014;58(3):309–318.
15. Hales CM, Harpaz R, Ortega-Sanchez I, Bialek SR; Centers for Disease Control and Prevention (CDC). Update on recommendations for use of herpes zoster vaccine. MMWR Morb Mortal Wkly Rep. 2014;63(33):729–731.
16. Centers for Disease Control and Prevention. Chickenpox (Varicella). Monitoring the Impact of Varicella Vaccination. Updated July 1, 2016. https://www.cdc.gov/chickenpox/surveillance/monitoring-varicella.html. Accessed April 11, 2017.
17. Petrosky E, Bocchini JA Jr, Hariri S, et al. Use of 9-valent human papillomavirus (HPV) vaccine: updated HPV vaccination recommendations of the Advisory Committee on Immunization Practices. MMWR Morb Mortal Wkly Rep. 2015;64(11):300–304.
18. Meites E, Kempe A, Markowitz LE. Use of a 2-dose schedule for human papillomavirus vaccination–updated recommendations of the Advisory Committee on Immunization Practices. MMWR Morb Mortal Wkly Rep. 2016;65(49):1405–1408.
19. Grohskopf LA, Sokolow LZ, Broder KR, et al. Prevention and control of seasonal influenza with vaccines. MMWR Recomm Rep. 2016;65(5):1–54.
20. Centers for Disease Control and Prevention. Updated recommendations for use of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) in pregnant women–Advisory Committee on Immunization Practices (ACIP), 2012. MMWR Morb Mortal Wkly Rep. 2013;62(7):131–135.
21. Amirthalingam G, Andrews N, Campbell H, et al. Effectiveness of maternal pertussis vaccination in England: an observational study. Lancet 2014;384(9953):1521–1528.
22. Munoz FM, Bond NH, Maccato M, et al. Safety and immunogenicity of tetanus diphtheria and acellular pertussis (Tdap) immunization during pregnancy in mothers and infants: a randomized clinical trial. JAMA. 2014;311(17):1760–1769.
23. Centers for Disease Control and Prevention (CDC). Updated recommendations for use of tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine (Tdap) in pregnant women and persons who have or anticipate having close contact with an infant aged <12 months–Advisory Committee on Immunization Practices (ACIP), 2011. MMWR Morb Mortal Wkly Rep. 2011;60(41):1424–1426.
24. Hales CM, Harpaz R, Ortega-Sanchez I, Bialek SR; Centers for Disease Control and Prevention (CDC). Update on recommendations for use of herpes zoster vaccine. MMWR Morb Mortal Wkly Rep. 2014;63(33):729–731.
25. Harpaz R, Ortega-Sanchez IR, Seward JF; Advisory Committee on Immunization Practices (ACIP) Centers for Disease Control and Prevention (CDC). Prevention of herpes zoster: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 2008;57(RR-5):1–30.
26. Cook SJ, Flaherty DK. Review of the persistence of herpes zoster vaccine efficacy in clinical trials. Clin Ther. 2015;37(11):2388–2397.
27. Tomczyk S, Bennett NM, Stoecker C, et al; Centers for Disease Control and Prevention (CDC). Use of 13-valent pneumococcal conjugate vaccine and 23-valent pneumococcal polysaccharide vaccine among adults aged >65 years: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Morb Mortal Wkly Rep. 2014;63(37):822–825.
28. Kobayashi M, Bennett NM, Gierke R, et al. Intervals between PCV13 and PPSV23 vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Morb Mortal Wkly Rep. 2015;64(34):944–947.
29. Dubé E, Laberge C, Guay M, et al. Vaccine hesitancy: an overview. Hum Vaccin Immunother.2013;9(8):1763–1773.
30. Jacobson RM, St Sauver JL, Finney Rutten LJ. Vaccine hesitancy. Mayo Clin Proc. 2015;90(11):1562–1568.
31. Jarrett C, Wilson R, O’Leary M, et al; SAGE Working Group on Vaccine Hesitancy. Strategies for addressing vaccine hesitancy–a systematic review. Vaccine. 2015;33(34):4180–4190.
32. Leask J, Kinnersley P, Jackson C, et al. Communicating with parents about vaccination: a framework for health professionals. BMC Pediatr. 2012;12:154.
33. Centers for Disease Control and Prevention. Vaccine Storage & Handling Toolkit. June 2016. https://www.cdc.gov/vaccines/hcp/admin/storage/toolkit/storage-handling-toolkit.pdf. Accessed April 11, 2017.
34. Immunization Action Coalition. Administering Vaccines: Dose, Route, Site, and Needle Size. http://www.immunize.org/catg.d/p3085.pdf. Accessed April 11, 2017.