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This report updates CDC's recommendations for using yellow fever vaccine (CDC. Yellow Fever Vaccine: Recommendations of the Advisory Committee on Immunizations Practices: MMWR 1990;39[No. RR-6]1--6). The 2002 recommendations include new or updated information regarding 1) reports of yellow fever vaccine-associated viscerotropic disease (previously reported as febrile multiple organ system failure); 2) use of yellow fever vaccine for pregnant women and persons infected with human immunodeficiency virus (HIV); and 3) concurrent use of yellow fever vaccine with other vaccines. A link to this report and other information related to yellow fever can be accessed at the website for Travelers' Health, Division of Global Migration and Quarantine, National Center for Infectious Diseases, CDC, at http://www.cdc.gov/travel/index.htm, and through the website for the Division of Vector-Borne Infectious Diseases, National Center for Infectious Diseases, CDC, at http://www.cdc.gov/ncidod/dvbid/yellowfever/index.htm. [ABSTRACT FROM AUTHOR]

Objective: To evaluate coronavirus disease 2019 (COVID-19) vaccine hesitancy among healthcare personnel (HCP) with significant clinical exposure to COVID-19 at 2 large, academic hospitals in Philadelphia, Pennsylvania., Design, Setting, and Participants: HCP were surveyed in November-December 2020 about their intention to receive the COVID-19 vaccine., Methods: The survey measured the intent among HCP to receive a COVID-19 vaccine, timing of vaccination, and reasons for or against vaccination. Among patient-facing HCP, multivariate regression evaluated the associations between healthcare positions (medical doctor, nurse practitioner or physician assistant, and registered nurse) and vaccine hesitancy (intending to decline, delay, or were unsure about vaccination), adjusting for demographic characteristics, reasons why or why not to receive the vaccine, and prior receipt of routine vaccines., Results: Among 5,929 HCP (2,253 medical doctors [MDs] and doctors of osteopathy [DOs], 582 nurse practitioners [NPs], 158 physician assistants [PAs], and 2,936 nurses), a higher proportion of nurses (47.3%) were COVID-vaccine hesitant compared with 30.0% of PAs and NPs and 13.1% of MDs and DOs. The most common reasons for vaccine hesitancy included concerns about side effects, the newness of the vaccines, and lack of vaccine knowledge. Regardless of position, Black HCP were more hesitant than White HCP (odds ratio [OR], ∼5) and females were more hesitant than males (OR, ∼2)., Conclusions: Although most clinical HCP intended to receive a COVID-19 vaccine, intention varied by healthcare position. Consistent with other studies, hesitancy was also significantly associated with race or ethnicity across all positions. These results highlight the importance of understanding and effectively addressing reasons for hesitancy, especially among frontline HCP who are at increased risk of COVID exposure and play a critical role in recommending vaccines to patients.

Importance: Significant differences in hesitancy to receive COVID-19 vaccination by race/ethnicity have been observed in several settings. Racial/ethnic differences in COVID-19 vaccine hesitancy among health care workers (HCWs), who face occupational and community exposure to COVID-19, have not been well described., Objective: To assess hesitancy to COVID-19 vaccination among HCWs across different racial/ethnic groups and assess factors associated with vaccine hesitancy., Design, Setting, and Participants: This survey study was conducted among HCWs from 2 large academic hospitals (ie, a children's hospital and an adult hospital) over a 3-week period in November and December 2020. Eligible participants were HCWs with and without direct patient contact. A 3-step hierarchical multivariable logistic regression was used to evaluate associations between race/ethnicity and vaccine hesitancy controlling for demographic characteristics, employment characteristics, COVID-19 exposure risk, and being up to date with routine vaccinations. Data were analyzed from February through March 2021., Main Outcomes and Measures: Vaccine hesitancy, defined as not planning on, being unsure about, or planning to delay vaccination, served as the outcome., Results: Among 34 865 HCWs eligible for this study, 12 034 individuals (34.5%) completed the survey and 10 871 individuals (32.2%) completed the survey and reported their race/ethnicity. Among 10 866 of these HCWs with data on sex, 8362 individuals (76.9%) were women, and among 10 833 HCWs with age data, 5923 individuals (54.5%) were younger than age 40 years. (Percentages for demographic and clinical characteristics are among the number of respondents for each type of question.) There were 8388 White individuals (77.2%), 882 Black individuals (8.1%), 845 Asian individuals (7.8%), and 449 individuals with other or mixed race/ethnicity (4.1%), and there were 307 Hispanic or Latino individuals (2.8%). Vaccine hesitancy was highest among Black HCWs (732 individuals [83.0%]) and Hispanic or Latino HCWs (195 individuals [63.5%]) (P < .001). Among 5440 HCWs with vaccine hesitancy, reasons given for hesitancy included concerns about side effects (4737 individuals [87.1%]), newness of the vaccine (4306 individuals [79.2%]), and lack of vaccine knowledge (4091 individuals [75.2%]). The adjusted odds ratio (aOR) for vaccine hesitancy was 4.98 (95% CI, 4.11-6.03) among Black HCWs, 2.10 (95% CI, 1.63-2.70) among Hispanic or Latino HCWs, 1.48 (95% CI, 1.21-1.82) among HCWs with other or mixed race/ethnicity, and 1.47 (95% CI, 1.26-1.71) among Asian HCWs compared with White HCWs (P < .001). The aOR was decreased among Black HCWs when adjusting for employment characteristics and COVID-19 exposure risk (aOR, 4.87; 95% CI, 3.96-6.00; P < .001) and being up to date with prior vaccines (aOR, 4.48; 95% CI, 3.62-5.53; P < .001) but not among HCWs with other racial/ethnic backgrounds., Conclusions and Relevance: This study found that vaccine hesitancy before the authorization of the COVID-19 vaccine was increased among Black, Hispanic or Latino, and Asian HCWs compared with White HCWs. These findings suggest that interventions focused on addressing vaccine hesitancy among HCWs are needed.

Background: Influenza vaccination of healthcare workers (HCWs) has been recommended for more than 30 years. In 2009, HCWs were designated as a priority group by the Centers for Disease Control and Prevention. Current HCW vaccination rates are 78% across all settings and reach approximately 92% among those employed in hospital settings. Over the last decade, it has become clear that mandatory vaccine policies result in maximal rates of HCW immunization., Methods: In this observational 10-year study, we describe the implementation of a mandatory influenza vaccination policy in a dedicated quaternary pediatric hospital setting by a multidisciplinary team. We analyzed 10 years of available data from deidentified occupational health records from 2009-2010 through the 2018-2019 influenza seasons. Descriptive statistics were performed using Stata v15 and Excel., Results: Sustained increases in HCW immunization rates above 99% were observed in the 10 years postimplementation, in addition to a reduction in exemption requests and healthcare-associated influenza. In the year of implementation, 145 (1.6%) HCWs were placed on temporary suspension for failure to receive the vaccine without documentation of an exemption, with 9 (0.06%) subsequently being terminated. Since then, between 0 and 3 HCWs are terminated yearly for failure to receive the vaccine., Conclusions: Implementation of our mandatory influenza vaccination program succeeded in successfully increasing the proportion of immunized HCWs at a quaternary care children's hospital, reducing annual exemption requests with a small number of terminations secondary to vaccine refusal. Temporal trends suggest a positive impact on the safety of our patients., (© The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Background: Health care personnel have been identified by the ACIP as a priority group for COVID-19 vaccination. We conducted a survey in November-December 2020 at two large, academic hospitals in Philadelphia to evaluate the intention of hospital employees to be vaccinated., Methods: The survey was sent electronically to all employees (clinical and nonclinical staff) at a children's hospital and an adult hospital. The survey was voluntary and confidential. Questions focused on plans to receive a COVID-19 vaccine when available, reasons why employees would/would not get vaccinated, when employees planned to be vaccinated, vaccine safety and efficacy features that would be acceptable, and past history of receipt of other vaccines by the employee and family. Responses were analyzed using univariate and multiple logistic regression methods., Results: A total of 12,034 hospital employees completed the survey (a 34.5% response rate). Overall, 63.7% of employees reported that they planned to receive a COVID-19 vaccine, 26.3% were unsure, and 10.0% did not plan to be vaccinated. Over 80% of those unsure or unwilling to be vaccinated expressed concerns about vaccine side effects and the vaccines' newness. In multivariable logistic regression, persons planning to take a COVID-19 vaccine were more likely to be older, male, more educated, Asian or White, up-to-date on vaccinations, without direct patient contact, and tested for COVID-19 in the past. No significant difference in intention to be vaccinated was found between those with higher versus lower levels of exposure to COVID-19 patients or the number of previous exposures to patients with COVID-19., Conclusions: While the majority of hospital employees are planning to receive a COVID-19 vaccine, many are unsure or not planning to do so. Further education of hospital employees about the safety, efficacy, and value of the currently available COVID-19 vaccines is critical to vaccine acceptance in this population., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Recently, efforts have been made to fill a so-called "vaccine gap" between Japan and other countries; however, more work remains. Concerns about adverse events following immunization (AEFI) resulted in an historically passive approach to policy making in the National Immunization Program (NIP). For example, reports of AEFI following human papillomavirus vaccine (HPVV) in 2013 led the Japanese government to withdraw its proactive recommendations, resulting in a sharp drop in HPVV coverage rate to less than 1.0%. In this report, we review key historical incidents that led to the current immunization system in Japan, compare it to that in the United States, and discuss strategies for improving the Japanese immunization system. By strengthening existing policies and programs, such as National Immunization Technical Advisory Groups and AEFI reporting, compensation laws, and immunization education, the remaining vaccine gap in Japan could be filled., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The World Health Organization has named vaccine hesitancy as one of the top ten threats to global health in 2019. The reasons why people choose not to vaccinate are complex, but lack of confidence in vaccine safety, driven by concerns about adverse events, has been identified as one of the key factors. Healthcare workers, especially those in primary care, remain key influencers on vaccine decisions. It is important, therefore, that they be supported by having easy access to trusted, evidence-based information on vaccines. Although parents and patients have a number of concerns about vaccine safety, among the most common are fears that adjuvants like aluminum, preservatives like mercury, inactivating agents like formaldehyde, manufacturing residuals like human or animal DNA fragments, and simply the sheer number of vaccines might be overwhelming, weakening or perturbing the immune system. As a consequence, some fear that vaccines are causing autism, diabetes, developmental delays, hyperactivity, and attention-deficit disorders, amongst others. In this review we will address several of these topics and highlight the robust body of scientific evidence that refutes common concerns about vaccine safety., (Copyright © 2020 Geoghegan, O’Callaghan and Offit.)

Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Dorit Reiss owns stock in GSK, a vaccine manufacturer, as part of a diverse portfolio.

Vaccines are everywhere hugely successful but are also under attack. The reason for the latter is the perception by some people that vaccines are unsafe. However that may be, vaccine safety, life any other scientific subject, must be constantly studied. It was from this point of view that a meeting was organized at the Wellcome Trust in London in May 2019 to assess some aspects of vaccine safety as subjects for scientific study. The objective of the meeting was to assess what is known beyond reasonable doubt and conversely what areas need additional studies. Although the meeting could not cover all aspects of vaccine safety science, many of the most important issues were addressed by a group of about 30 experts to determine what is already known and what additional studies are merited to assess the safety of the vaccines currently in use. The meeting began with reviews of the current situation in different parts of the world, followed by reviews of specific controversial areas, including the incidence of certain conditions after vaccination and the safety of certain vaccine components. Lastly, information about the human papillomavirus vaccine was considered because its safety has been particularly challenged by vaccine opponents. The following is a summary of the meeting findings. In addition to this summary, the meeting organizers will explore opportunities to perform studies that would enlarge knowledge of vaccine safety., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020.)

Concerns about vaccine safety can lead to decreased acceptance of vaccines and resurgence of vaccine-preventable diseases. We summarize the key evidence on some of the main current vaccine safety controversies in the United States, including (1) measles, mumps, and rubella vaccine and autism; (2) thimerosal, a mercury-based vaccine preservative and the risk of neurodevelopmental disorders; (3) vaccine-induced Guillain-Barré syndrome (GBS); (4) vaccine-induced autoimmune diseases; (5) safety of human papillomavirus vaccine; (6) aluminum adjuvant-induced autoimmune diseases and other disorders; and (7) too many vaccines given early in life predisposing children to health and developmental problems. A possible small increased risk of GBS following influenza vaccination has been identified, but the magnitude of the increase is less than the risk of GBS following influenza infection. Otherwise, the biological and epidemiologic evidence does not support any of the reviewed vaccine safety concerns., (Published by Oxford University Press for the Infectious Diseases Society of America 2019.)

Introduction: Japan has experienced extremely low human papillomavirus vaccine (HPVV) coverage following the suspension of proactive governmental recommendations in 2013. Several studies have reported that recommendations from physicians increase adolescents' vaccine acceptance. In this survey, we evaluated the attitudes and intentions of Japanese physicians related to adolescent immunizations, particularly HPVV., Methods: We conducted a cross-sectional study using a mailed questionnaire targeting 330 Japanese physicians including 78 pediatricians, 225 internists and 27 obstetricians and gynecologists (OB/GYNs) in Kawasaki City, Japan in 2016. The survey measured physicians' reported frequency of educating adolescents about vaccines as well as their own perceptions and intentions related to adolescent immunizations., Results: Valid responses were obtained from 148 (45%) physicians. Though 53% agreed that the HPVV should be recommended, only 21% reported educating about HPVV. The majority of respondents (90%) agreed that they would restart HPVV for adolescents if the government reinstated its recommendation., Conclusions: Although Japanese physicians reported support for adolescent immunizations, they were less likely to recommend or discuss HPVV compared with other adolescent vaccines. Responses indicated this was, at least in part, due to the lack of governmental support for HPVV, indicating that their recommendations would improve with government endorsement of the vaccine., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)

Rotavirus is the most important cause of gastroenteritis worldwide. In developing countries, the virus is a major cause of death in infants and young children. In the United States, before the licensure of vaccines, rotavirus infections accounted for ∼2.7 million cases of gastroenteritis annually. Here are described the history and challenges surrounding the development of a rotavirus vaccine.

Although juvenile-onset recurrent respiratory papillomatosis (JoRRP) generally involves a benign tumor on the larynx and other respiratory tract areas, almost all patients with this disease require repeated surgical intervention (to prevent airway obstruction during the course of illness) and various adjuvant therapies such as interferon, cidofovir, acyclovir, ribavirin, indole-3-carbinol, HspE7, mumps vaccine, photodynamic therapy, propranolol, cimetidine, and bevacizumab. Some case reports recently described the effectiveness of the quadrivalent human papillomavirus vaccine (HPV4) as an adjuvant therapy. On the basis of these reports, we administered HPV4 to a 2-year-old boy with JoRRP. However, no therapeutic effect was found. A review of the available literature revealed that current evidence for the effectiveness of therapeutic HPV4 and other adjuvant therapies for JoRRP is inconsistent. Therefore, the prophylactic use of currently available HPV vaccine for adolescents is the most effective strategy for preventing not only anogenital cancers but also genital warts, which might be a risk factor for JoRRP among their children in the future., (© The Author 2017. Published by Oxford University Press on behalf of The Journal of the Pediatric Infectious Diseases Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Objective: A cluster randomized trial was performed to evaluate an educational intervention to improve parental attitudes and vaccine uptake in vaccine-hesitant parents., Methods: Two primary care sites were randomized to provide families with either usual care or an intervention (video and written information) for vaccine-hesitant parents. Eligible parents included those presenting for their child's 2-week well-child visit with performance on the Parent Attitudes about Childhood Vaccines (PACV) survey suggesting vaccine hesitancy (score ≥25). Enrollees completed PACV surveys at the 2-month well-child visit and vaccination status at 12 weeks of age was assessed. The primary outcome was the difference in PACV scores obtained at enrollment and 2 months between the 2 groups. The proportion of on-time vaccination was also compared at 12 weeks., Results: A total of 454 parents were approached, and 369 (81.3%) participated; 132 had PACV scores of ≥25 and were enrolled, 67 in the control group (mean PACV score 37) and 55 in the intervention group (mean PACV score 40). Two-month PACV surveys were completed by 108 (∼90%) of enrollees. Parents in the intervention group had a significant decrease in PACV score at 2 months compared to control (median difference 6.7, P = .049); this remained significant after adjustment for baseline PACV score, race/ethnicity, and income (P = .044). There was no difference in the on-time receipt of vaccines between groups at 12 weeks., Conclusions: A brief educational intervention for vaccine-hesitant parents was associated with a modest but significant increase in measured parental attitudes toward vaccines., (Copyright © 2013 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.)

Rotaviruses cause extensive morbidity and mortality worldwide, thus corroborating the need for a vaccine that is effective in all socioeconomic environments. Vaccines evaluated in clinical trials have all been live attenuated rotaviruses that are delivered orally to mimic the excellent protection observed after natural infection. The mechanisms by which these vaccine candidates or wild-type rotaviruses elicit protection are not fully understood. During the 1980s, several candidate vaccines provided little protection, particularly in developing countries, and were discontinued. Two, however, are in the process of being licensed worldwide, and several others are undergoing clinical trials. Development of live rotavirus vaccines has been highly influenced by views regarding the importance of serotype-specific neutralizing antibody. Development of several candidate vaccines is based on the concept that neutralizing antibody is the primary determinant of protection. These candidates, including 1 of the 2 being licensed worldwide (RotaTeq), are composed of multiple rotavirus strains representative of the major human rotavirus serotypes. The other group of candidates has been developed based on the theory that protection is not solely dependent on neutralizing antibody. These candidates are composed of single rotavirus strains and include the other vaccine being licensed worldwide (Rotarix). Studies that provide the basis for each approach will be presented and discussed.

Although child vaccination rates remain high, some parental concern persists that vaccines might cause autism. Three specific hypotheses have been proposed: (1) the combination measles-mumps-rubella vaccine causes autism by damaging the intestinal lining, which allows the entrance of encephalopathic proteins; (2) thimerosal, an ethylmercury-containing preservative in some vaccines, is toxic to the central nervous system; and (3) the simultaneous administration of multiple vaccines overwhelms or weakens the immune system. We will discuss the genesis of each of these theories and review the relevant epidemiological evidence.

In October 2007, Dr Robert Sears, in response to growing parental concerns about the safety of vaccines, published The Vaccine Book: Making the Right Decision for Your Child. Sears' book is enormously popular, having sold >40000 copies. At the back of the book, Sears includes "Dr Bob's Alternative Vaccine Schedule," a formula by which parents can delay, withhold, separate, or space out vaccines. Pediatricians now confront many parents who insist that their children receive vaccines according to Sears' schedule, rather than that recommended by the American Academy of Pediatrics, the Centers for Disease Control and Prevention, and the American Academy of Family Physicians. This article examines the reasons for the popularity of Sears' book, deconstructs the logic and rationale behind its recommendations, and describes how Sears' misrepresentation of vaccine science misinforms parents trying to make the right decisions for their children.

Background: Infantile gastroenteritis caused by human rotaviruses is a prevalent disease throughout the world, causing dehydration and hospitalization in all countries. In developing countries, it is associated with a high mortality. A licensed vaccine against rotavirus was withdrawn because of a causal association with intussusception. A new vaccine has been developed and is a candidate for licensure., Methods: To recount the early development and recent demonstration of the safety and efficacy of the new vaccine. A bovine rotavirus attenuated for humans was isolated and reassorted with human rotaviruses of serotypes G1-4 and P1 to create a pentavalent vaccine. Multiple placebo-controlled clinical trials, including one involving approximately 70,000 infants, were conducted in multiple developed countries., Results: The pentavalent vaccine was well tolerated by infants less than 8 months of age, and the incidence of intussusception was similar among vaccine and placebo recipients. More than 90% of infants had a significant rise in serum antirotavirus IgA titer after 3 doses. Efficacy of 95% against severe disease causing hospitalization or emergency care was demonstrated, and pentavalent vaccine prevented 74% of all rotavirus disease., Conclusions: If widely used, pentavalent vaccine would control rotavirus disease in the United States and other developed countries and could also have a major effect in developing countries.

Background: Rotavirus gastroenteritis, which causes substantial infant mortality and morbidity worldwide, is a vaccine-preventable disease. The purpose of this study was to evaluate different compositions and potencies (vaccine virus titers) of a live multivalent human-bovine (WC3) reassortant rotavirus vaccine in order to select the potency and composition of the vaccine for further development., Methods: The efficacy, safety, and immunogenicity of a G1, G2, G3, G4, and P1A pentavalent composition at three different potencies, a G1, G2, G3, G4 quadrivalent composition, and a P1A monovalent composition of an oral human-bovine (WC3) reassortant rotavirus vaccine were compared in a blinded, placebo-controlled trial conducted between 1998 and 2001 enrolling 1,946 healthy Finnish infants 2-8 months of age., Results: All potencies of the pentavalent and quadrivalent vaccines were efficacious (58-74%) against wild-type rotavirus gastroenteritis of any severity and 100% protective against severe rotavirus disease caused by vaccine G-serotypes through the first rotavirus season post-vaccination. The monovalent P1A vaccine was 53% efficacious against moderate-and-severe rotavirus gastroenteritis. Protection against rotavirus gastroenteritis of any severity was demonstrated through two and three rotavirus seasons for all vaccine compositions. After the third dose, the percentage of infants with >or=3-fold rise in baseline serum neutralizing antibody titers against G1 ranged from 62% to 86% for recipients of the pentavalent vaccine, depending on the potency. The incidence of fever, irritability, vomiting, and diarrhea did not significantly differ between vaccine and placebo groups. A 7-month-old male developed intussusception 9 days after the first dose of the low-potency pentavalent vaccine., Conclusions: Based on the results of this trial, a pentavalent composition (G1, G2, G3, G4, and P1A) of human-bovine (WC3) reassortant rotavirus vaccine with a potency similar to that of the middle-potency pentavalent vaccine ( approximately 8 x 10(6) plaque-forming units/dose) was selected for further development.

Background: Rotavirus is a leading cause of childhood gastroenteritis and death worldwide., Methods: We studied healthy infants approximately 6 to 12 weeks old who were randomly assigned to receive three oral doses of live pentavalent human-bovine (WC3 strain) reassortant rotavirus vaccine containing human serotypes G1, G2, G3, G4, and P[8] or placebo at 4-to-10-week intervals in a blinded fashion. Active surveillance was used to identify subjects with serious adverse and other events., Results: The 34,035 infants in the vaccine group and 34,003 in the placebo group were monitored for serious adverse events. Intussusception occurred in 12 vaccine recipients and 15 placebo recipients within one year after the first dose including six vaccine recipients and five placebo recipients within 42 days after any dose (relative risk, 1.6; 95 percent confidence interval, 0.4 to 6.4). The vaccine reduced hospitalizations and emergency department visits related to G1-G4 rotavirus gastroenteritis occurring 14 or more days after the third dose by 94.5 percent (95 percent confidence interval, 91.2 to 96.6 percent). In a nested substudy, efficacy against any G1-G4 rotavirus gastroenteritis through the first full rotavirus season after vaccination was 74.0 percent (95 percent confidence interval, 66.8 to 79.9 percent); efficacy against severe gastroenteritis was 98.0 percent (95 percent confidence interval, 88.3 to 100 percent). The vaccine reduced clinic visits for G1-G4 rotavirus gastroenteritis by 86.0 percent (95 percent confidence interval, 73.9 to 92.5 percent)., Conclusions: This vaccine was efficacious in preventing rotavirus gastroenteritis, decreasing severe disease and health care contacts. The risk of intussusception was similar in vaccine and placebo recipients. (ClinicalTrials.gov number, NCT00090233.), (Copyright 2006 Massachusetts Medical Society.)

During the past fifty years, the number of pharmaceutical companies making vaccines has decreased dramatically, and those that still make vaccines have reduced resources to make new ones. Pharmaceutical companies are gradually abandoning vaccines because the research, development, testing, and manufacture of vaccines are expensive and because the market to sell vaccines is much smaller than the market for other drug products. Congressional action could assure both a steady supply of existing vaccines and the promise of vaccines for the future.

Rotavirus causes severe and often lifethreatening illness. Universal application of a safe and protective vaccine is justified in both developed and developing nations. Two vaccine candidates, one monovalent (Rotarix) and one multivalent (Rotateq), appear to meet these requirements and are likely to be licensed in the United States in the next 2 or 3 years. Both vaccines exhibited similar safety characteristics. There is little doubt that Rotateq and Rotarix will be shown to be effective for routine protection of infants. Unfortunately, despite numerous clinical trials, the most common serotype (PlaGa) commonly has been encountered as a natural challenge. Therefore, it is not known whether either vaccine possesses advantages in different epidemiological situations. Continuing the analogy with influenza virus, it may be that optimum protection against different serotypes requires a vaccine that is precisely homologous in antigen composition. If so, Rotateq would provide protection against the most common serotype PlaG1 because in includes both Pla and G1 rotavirus reassortants. Further, it would be expected to provide superior protection against G2, G3, and G4 wild-type virus because it contains reassortants of those specificities. In the case of a natural challenge with a serotype that was not G1, G2, G3, or G4, a Rotateq preparation containing a WC3 reassortant expressing the new G serotype could be formulated readily. The monotypic Rotarix may provide ideal protection against the PlaG1 rotavirus because it is composed solely of the PlaG1 strain. It may also provide cross-protection against other rotavirus serotypes adequate to protect against severe and life-threatening disease. In such a case, its monotypic composition may also provide significant economic savings in manufacturing. The resolution of these questions may have to await extensive post-licensure experience with each vaccine. In the future, possible application of rotavirus vaccine for other situations also should be explored, including use in older children to limit nosocomial infection, use in geriatric populations, use in the immunocompromised host, and possibly use in parents and other adults in contact with infants with rotavirus. Both Rotarix and Rotateq likely are to be launched at prices beyond those affordable in the poorest and neediest less-developed countries. It is essential that there be vigorous pursuit of new technologies to manufacture these products at drastically reduced cost if their true lifesaving potential is to be achieved.

A quadrivalent precursor to the pentavalent rotavirus vaccine candidate RotaTeq was evaluated in a 3-dose, 439-subject study. To determine immunogenicity, the quantity of rotavirus immunoglobulin A (IgA) in stool specimens obtained, at 1 of 10 study sites, from 37 placebo and 37 vaccine recipients was measured. None of the placebo recipients showed a clinically important (>/=3-fold) increase in stool rotavirus IgA, whereas 31 vaccine recipients showed an increase after at least 1 dose of vaccine. In total, 16, 19, and 15 vaccine recipients had increases after 1, 2, and 3 doses, respectively, indicating that a 3-dose regimen increased the immune response elicited by this vaccine.