Development,Production, and Postmarketing Surveillance of Hepatitis A Vaccines in China

China has long experience using live attenuated and inactivated vaccines against hepatitis A virus (HAV) infection. We summarize this experience and provide recent data on adverse events after immunization (AEFIs) with hepatitis A vaccines in China. We reviewed the published literature (in Chinese and English) and the published Chinese regulatory documents on hepatitis A vaccine development, production, and postmarketing surveillance of AEFI. We described the safety, immunogenicity, and efficacy of hepatitis A vaccines and horizontal transmission of live HAV vaccine in China. In clinical trials, live HAV vaccine was associated with fever (0.4%–5% of vaccinees), rash (0%–1.1%), and elevated alanine aminotransferase (0.015%). Inactivated HAV vaccine was associated with fever (1%–8%), but no serious AEFIs were reported. Live HAV vaccine had seroconversion rates of 83% to 91%, while inactivated HAV vaccine had seroconversion rates of 95% to 100%. Community trials showed efficacy rates of 90% to 95% for live HAV and 95% to 100% for inactivated HAV vaccine. Postmarketing surveillance showed that HAV vaccination resulted in an AEFI incidence rate of 34 per million vaccinees, which accounted for 0.7% of adverse events reported to the China AEFI monitoring system. There was no difference in AEFI rates between live and inactivated HAV vaccines. Live and inactivated HAV vaccines manufactured in China were immunogenic, effective, and safe. Live HAV vaccine had substantial horizontal transmission due to vaccine virus shedding; thus, further monitoring of the safety of virus shedding is warranted.Key words: hepatitis A, vaccine, safety, efficacy     

Vaccination recommendations for patients with neuromuscular disease

Neuromuscular diseases (NMDs) encompass a broad spectrum of conditions. Because infections may be relevant to the final prognosis of most NMDs, vaccination appears to be the simplest and most effective solution for protecting NMD patients from vaccine-preventable infections. However, very few studies have evaluated the immunogenicity, safety, tolerability, and efficacy of different vaccines in NMD patients; therefore, detailed vaccination recommendations for NMD patients are not available. Here, we present vaccination recommendations from a group of Italian Scientific Societies for optimal disease prevention in NMD patients that maintain high safety levels. We found that NMD patients can be classified into two groups according to immune function: patients with normal immunity and patients who are immunocompromised, including those who intermittently or continuously take immunosuppressive therapy. Patients with normal immunity and do not take immunosuppressive therapy can be vaccinated as healthy subjects. In contrast, immunocompromised patients, including those who take immunosuppressive therapy, should receive all inactivated vaccines as well as influenza and pneumococcal vaccines; these patients should not be administered live attenuated vaccines. In all cases, the efficacy and long-term persistence of immunity from vaccination in NMD patients can be lower than in normal subjects. Household contacts of immunocompromised NMD patients should also be vaccinated appropriately.     

IgE sensitization to gelatin: the probable role of gelatin-containing diphtheria-tetanus-acellular pertussis (DTaP) vaccines

We recently found that most events of anaphylaxis to live attenuated viral vaccines containing gelatin as a stabilizer might be caused by the gelatin. However, the mechanism that the children were sensitized to gelatin was unclear. In Japan, both diphtheria-tetanus-acellular pertussis (DTaP) vaccines with and without gelatin are available. We explored the possibility that gelatin-containing DTaP vaccines before live viral vaccines sensitize children to gelatin. We received the serum samples of 87 children who had systemic immediate-type reactions including anaphylaxis to the vaccines from both physicians and vaccine manufacturers throughout Japan. We then surveyed the DTaP vaccination histories of the children who demonstrated anti-gelatin IgE. Of the above 87 children, 79 (91%) had anti-gelatin IgE. We successfully collected DTaP vaccination histories including the manufacturers' names and numbers of doses on 55 children. Only one child had not received any DTaP vaccine, the other 54 had received gelatin-containing DTaP vaccines and none received gelatin-free DTaP vaccines. We concluded that there was a strong causal relationship between gelatin-containing DTaP vaccination, anti-gelatin IgE production, and risk of anaphylaxis following subsequent immunization with live viral vaccines which contain a larger amount of gelatin.     

Current status and prospects of live varicella vaccine

Since its development in 1974 the Oka strain live attenuated varicella vaccine has been tested in healthy and immunocompromised adults and children. Its safety and efficacy have been established and it is now licensed for general use in Japan and Korea, and for immunocompromised patients in several other countries. Possibilities for the future include its use to prevent zoster in the elderly, its incorporation in a multivalent vaccine and its use as a vehicle to express foreign genes in recombinant vaccines.     

Healthcare workers’ knowledge,beliefs, and coverage regarding vaccinations in critical care units in Italy

BackgroundLow rates of vaccine coverage have resulted in a resurgence of several vaccine-preventable diseases in many European countries. Routine vaccination of healthcare workers (HCWs) is important to reduce disease transmission, and to promote vaccine awareness and acceptance in the population. The objectives of this cross-sectional study were to investigate knowledge and beliefs about vaccines and to evaluate self-reported immunization coverage with vaccines recommended for HCWs. Additionally, the effects of several factors on these outcomes have been evaluated.MethodsA survey was conducted between September and November 2018 among a random sample of HCWs in cardiac, adult, and neonatal critical care units of 8 randomly selected hospitals across the Campania and Calabria Regions in Italy. Multivariate logistic and linear regression analysis has been performed.ResultsA total 531 HCWs returned the questionnaire for a response rate of 54.9%. Based on a vaccination knowledge score ranging from 0 to 9, more than half of the participants (55.4%) knew few of the vaccines recommended for HCWs (≤3 correct answers), 16.2% knew some vaccines (4–6 correct answers), and 28.4% knew most vaccines (≥7 correct answers), and only 13.2% knew all the vaccines recommended for HCWs. However, two-thirds (62.2%) knew that hepatitis B and influenza vaccines were recommended, and this knowledge was significantly higher among females (p < 0.001), among HCWs aged between 50 and 59 years (p = 0.01) compared with those aged < 30 years, and in those who search for information about recommended vaccines for HCWs (p = 0.012). The vaccine knowledge was significantly lower among nurses and nursing supporting staff compared with physicians (p = 0.032). Approximately two-thirds (62.7%) of HCWs considered themselves at risk of contracting vaccine-preventable infectious diseases during their professional practice. High rates of coverage were self-reported for hepatitis B (96.3%), tetanus and pertussis (93.7%), whereas they were lower for measles/mumps/rubella (80.5%), chickenpox (65.3%), and influenza (35.8%). Only 9.2% of HCWs reported prior receipt of all recommended vaccines. Male HCWs were less likely to report prior receipt of all recommended vaccines (p = 0.011). HCWs aged between 30 and 39 years compared with those aged < 30 years (p = 0.001) and those who knew some (p < 0.001) and most (p = 0.007) of all vaccines recommended for HCWs were more likely to self-report to be immunized.ConclusionsAdditional training about the vaccinations is needed to improve HCWs knowledge and to address specific concerns which may lead to better uptake among this group.     

Correlation between healthcare workers' knowledge of influenza vaccine and vaccine receipt.

OBJECTIVE: Influenza vaccine receipt by healthcare workers (HCWs) is important because HCWs are at risk for occupational exposure to influenza and may act as vectors in the nosocomial transmission of influenza. HCWs were surveyed to determine whether belief in commonly held influenza vaccine misconceptions was associated with influenza vaccine acceptance. DESIGN: Cross-sectional study. SETTING: A large urban teaching hospital. METHOD: A self-administered survey was used to assess nursing and physician staff influenza vaccine knowledge, current vaccination status, and potential reasons for vaccine declination. RESULTS: Two hundred twelve of 215 surveys were completed. The overall influenza vaccination rate was 73%. Physician staff were significantly more likely to have been vaccinated compared with nursing staff (82% vs 62%, respectively; P = .0009). HCWs answering the 5 influenza vaccine basic knowledge questions correctly were significantly more likely to have been vaccinated than those responding incorrectly to any question (84% vs 64%, respectively; P = .002). This association was present in the nursing group where 80% of those answering the knowledge questions correctly were vaccinated, but only 49% of those answering incorrectly were vaccinated (P = .000005). However, in the physician group, there was no significant difference in the influenza vaccination rates between those answering correctly and those answering incorrectly (P = .459). CONCLUSION: Belief in commonly held influenza vaccine misconceptions was significantly associated with influenza vaccine declination among nursing staff and may act as a barrier to greater rates of influenza vaccination. Reasons for influenza vaccine nonreceipt may differ between nursing and physician staff.     

Antibody responses and resistance to challenge in volunteers vaccinated with live attenuated, detergent split and oil adjuvant A2/Hong Kong/68 (H3N2) influenza vaccines: A report to the Medical Research Council Committee on Influenza and other Respiratory Virus Vaccines

Forty-nine subjects were vaccinated with either live attenuated, detergent split, or oil adjuvant A2/Hong Kong influenza vaccines, or a saline influenza B vaccine as control. Respiratory symptoms occurred more frequently in subjects who received the live vaccine but in total there was little difference between the symptoms in the four groups. Antibody titres in nasal washings and serum were measured by haemagglutination inhibition, neuraminidase inhibition and virus neutralization tests. The oil adjuvant vaccine stimulated larger antibody responses than the other procedures. Six weeks after vaccination the volunteers were challenged with partially attenuated live A2/Hong Kong influenza virus administered intranasally. The live attenuated and oil adjuvant vaccines provided the best protection against challenge.     

Seroprevalence of antibody to pandemic influenza A (H1N1) 2009 among healthcare workers after the first wave in Hong Kong

During the first wave of an influenza pandemic prior to the availability of an effective vaccine, healthcare workers (HCWs) may be at particular risk of infection with the novel influenza strain. We conducted a cross-sectional study of the prevalence of antibody to pandemic influenza A (H1N1) 2009 (pH1N1) among HCWs in Hong Kong in February-March 2010 following the first pandemic wave. Sera collected from HCWs were tested for antibody to pH1N1 influenza virus by viral neutralisation (VN). We assessed factors associated with higher antibody titres, and we compared antibody titres in HCWs with those in a separate community study. In total we enrolled 703 HCWs. Among 599 HCWs who did not report receipt of pH1N1 vaccine, 12% had antibody titre ≥1:40 by VN. There were no significant differences in the age-specific proportions of unvaccinated HCWs with antibody titre ≥1:40 compared with the general community following the first wave of pH1N1. Under good adherence to infection control guidelines, potential occupational exposures in the hospital setting did not appear to be associated with any substantial excess risk of pH1N1 infection in HCWs. Most HCWs had low antibody titres following the first pandemic wave.     

State of the art: Could nursing mothers be vaccinated with attenuated live virus vaccine?

Recently two cases of vaccine-associated neurologic disease have been reported in breastfed infants whose mothers had received live attenuated yellow fever vaccine. These two cases have focused attention on the transmission of attenuated yellow fever vaccine virus from mother to infant via breastfeeding, and more generally of all other live attenuated viruses used to immunize nursing mothers. This article provides an overview of the rare literature on possible virus excretion in breast milk after vaccination of nursing mothers with live attenuated virus vaccine and on cases of infection via breastfeeding in infants whose mothers had been vaccinated postpartum. Before implementing postpartum vaccination in a nursing mother, the vaccinator needs to weigh up the risk of transmission to and adverse effects in the baby from live vaccine virus against the beneficial effects of the vaccine for the mother, taking into account her need for vaccination.     

Vaccination of patients with diabetes mellitus--a retrospective study

402 subjects with diabetes mellitus have been vaccinated of the total of 34,000 vaccinees immunized during the study period of 9 and half months. Altogether 229 diabetic patients (56.97%) have been vaccinated'against tick-borne encephalitis (TBE) and 74 (18.4%) against viral hepatitis (41 types A+B, 30 type A, 3 type B). The average age in four most commonly administered vaccines (FSME IMMUN 0.5 ML, Twinrix Adult, Typhim Vi, and Havrix 1440) was 65, 52, 56, and 54 years, respectively. Live attenuated vaccines have been given to 6 patients with diabetes (1.49%)--- 5 travellers to endemic countries received the yellow fever vaccine Stamaril (1 female, 4 male) and one male patient varicella vaccine Varilrix. Among the least common vaccines in diabetic patients were those against invasive pneumococcal and meningococcal infections. Not a single unexpected side effect has been observed following the vaccination procedure in any diabetic patient. Based on the results of this retrospective study we can conclude that vaccination in diabetic patients is free of any ri-k- provided that there are no other contraindications, e.g. allergy to vaccine components or severe acute febrile illness. In the case of unstable glycaemia and significantly impaired immune system due to diabetes mellitus, vaccination with live attenuated vaccines should be carefully considered and measured against the risks of exposure to each and every specific infectious agent. There is no reason to be afraid of vaccination in diabetic patients provided that general contraindications are respected. On the contrary, this risk group can benefit from vaccination more remarkably since it may have some life-saving potential.     

Influenza vaccination with live-attenuated and inactivated virus-vaccines during an outbreak of disease.

Immunization procedures with live attenuated and inactivated vaccines were carried out on a group of young recruits at the beginning of an outbreak of infection due to an A/Victoria/3/75-related virus strain, which occurred in February 1977 in a military camp. A retrospective investigation on protection from clinical influenza was then performed in order to investigate whether immunization with live virus vaccines, administered at the beginning of an epidemic, could provide early protection from the disease. In the course of the two weeks following vaccination, laboratory-confirmed clinical influenza cases occurred in 4 subjects among the 110 volunteers of the control group which received placebo, and in 8, 7 and 4 subjects respectively of the 3 groups of about 125 individuals, each of which received one of the following vaccine preparations: (a), live attenuated A/Victoria/3/75 influenza virus oral vaccine, grown on chick embryo kidney culture; (b), live attenuated nasal vaccine, a recombinant of A/Puerto Rico/8/34 with A/Victoria/3/75 virus; and (c), inactivated A/Victoria/3/75 virus intramuscular vaccine. These data do not support the hypothesis that, during an epidemic of infection, early protection from clinical influenza can be achieved through immunization with live attenuated or inactivated influenza virus vaccines, in spite of the high immunizing capability of the vaccine preparations.     

Knowledge and attitude of Kenyan healthcare workers towards pandemic influenza disease and vaccination: 9 years after the last influenza pandemic

BackgroundHealthcare workers (HCWs) are at high risk of exposure and transmission of infectious respiratory pathogens like influenza. Despite the potential benefits, safety and efficacy of influenza vaccination, vaccines are still underutilized in Africa, including among HCWs.MethodFrom May-June 2018, we conducted a cross-sectional, self-administered, written survey among HCWs from seven counties in Kenya and assessed their knowledge attitudes and perceptions towards pandemic influenza disease and vaccination. Using regression models, we assessed factors that were associated with the HCW’s knowledge of pandemic influenza and vaccination.ResultsA total of 2,035 HCWs, representing 49% of the targeted respondents from 35 health facilities, completed the question. Sixty eight percent of the HCWs had ever heard of pandemic influenza, and 80.0% of these were willing to receive pandemic influenza vaccine if it was available. On average, Kenyan HCWs correctly answered 55.0% (95% CI 54.0–55.9) of the questions about pandemic influenza and vaccination. Physicians (65.6%, 95% CI 62.5–68.7) and pharmacists (61.7%, 95% CI 57.9–65.5) scored higher compared to nurses (53.1%, 95% CI 51.7–54.5). HCWs with 5 or more years of work experience (55.8, 95% CI 54.5–57.0) had marginally higher knowledge scores compared to those with less experience (53.9%, 95% CI 52.5–55.3). Most participants who were willing to receive pandemic influenza vaccine did so to protect their relatives (88.7%) or patients (85.9%).ConclusionOur findings suggest moderate knowledge of pandemic influenza and vaccination by HCWs in Kenya, which varied by cadre and years of work experience. These findings highlight the need for continued in-service health education to increase the HCW’s awareness and knowledge of pandemic influenza to increase acceptance of influenza vaccination in the case of a pandemic.     

Poor health care worker vaccination coverage and knowledge of vaccination recommendations in a tertiary Australia hospital

OBJECTIVES: Guidelines for vaccination of health care workers (HCWs) have been available in Victoria since 1998. We estimated knowledge and attitudes towards vaccination among HCWs as well as self-reported vaccination status in a tertiary adult hospital in Melbourne, Australia. METHODS: A cross-sectional survey was conducted in July 2000 using a telephone questionnaire and proportionate random sampling. RESULTS: Only 18% of 269 HCWs were fully vaccinated. Most (76%) had not heard of or seen current guidelines for HCW vaccination despite a stated belief in the importance of full vaccination (94%) and a willingness to update their vaccination status if necessary (96%). Less than half kept vaccination records (39%). Hepatitis B vaccination (95%) was most commonly completed. However, only half of all HCWs had received influenza vaccination in the past 12 months and other vaccines often had suboptimal coverage. A common reason cited for avoiding vaccination was concern over vaccine side effects (17%). While the hospital staff clinic was an acceptable site for vaccination, improved access was seen as important. CONCLUSIONS: HCW vaccination coverage and knowledge of vaccination requirements were poor. Concerns about vaccine side effects were common. Implications: Adequately resourced HCW vaccination programs that include ongoing education for HCWs and improved access to vaccination are necessary to improve vaccination coverage and reduce the risk of vaccine-preventable diseases among staff and patients.     

Vaccination of healthcare personnel: Spotlight on groups with underlying conditions

Healthcare personnel (HCP) are at increased risk of acquiring vaccine-preventable diseases (VPDs). Vaccination protects HCP and their patients from nosocomial transmission of VPDs. HCP who have underlying diseases (e.g., immunocompromised, HIV-infected, or those with chronic diseases) and HCP in particular phases of life (e.g., pregnant, elderly) require special consideration in regards the provision of vaccines. On the one hand, live virus vaccines may be contraindicated (e.g., pregnant HCP, immunocompromised HCP), while on the other hand, vaccines not routinely recommended (e.g., pneumococcal) may be indicated (e.g., elderly or immunocompromised HCP). It is not known how many HCP with underlying conditions require special consideration in the healthcare setting. This is an important issue, because the risk for serious morbidity, complications and mortality for HCP with underlying conditions will only increase. The prevention of nosocomial infections requires comprehensive occupational safety programs. The healthcare system must engage HCP and occupational physicians to ensure sufficient vaccination rates as part of an effective nosocomial infection prevention and HCP safety strategy.     

Safety profile and SARS-CoV-2 breakthrough infections among HCWs receiving anti-SARS-CoV-2 and influenza vaccines simultaneously: an Italian observational study

In October/December 2021, World Health Organization and other international agencies recommended the offer of the third dose of anti-SARS-CoV-2 vaccine. In this period, the routine offer of seasonal influenza vaccination was also guaranteed and simultaneous administration of the two vaccines was encouraged.This study aims to evaluate the safety profile and to estimate the incidence of SARS-CoV-2 breakthrough infections in subjects receiving the anti-SARS-CoV-2 and influenza vaccines simultaneously.The study population was represented by healthcare workers (HCWs) of Bari Policlinico General Hospital who received the influenza (Flucelvax Tetra®) and/or anti-SARS-CoV-2 vaccination (BNT162b2 mRNA COVID-19 vaccine, Comirnaty®) either in coadministration or separately in October 2021. Reports of adverse events following immunization (AEFIs) were investigated to study the safety of both vaccines in coadministration and in separate-instance administration. Post-vaccination SARS-CoV-2 breakthrough infection was also studied.942 HCWs accepted to join our study. 610/942 received both vaccines simultaneously. 25.26 % subjects (238/942) were only vaccinated against SARS-CoV-2, while the remaining 94 HCWs received the influenza vaccination first and subsequently received the anti-SARS-CoV2 booster dose.717 HCWs reported AEFIs (Reporting Rate 76.1 per 100 subjects). Simultaneous administration of the two vaccines was not related with an increase of the rate of AEFIs compared to the single administration of SARS-CoV-2 vaccine, but the AEFIs’ rate was lower among subjects who received only influenza vaccine.Post-vaccination SARS-CoV-2 infections were notified for 41.5 % of enrolled subjects (391/942). Incidence of breakthrough infection and symptomatic disease was not significantly different between the simultaneous administration group and other subjects.Our data suggests that simultaneous administration of a quadrivalent influenza vaccine and an mRNA anti-SARS-CoV-2 vaccine neither affected the safety of said products nor was associated with a higher risk of SARS-CoV-2 breakthrough infection.     

Biosafety aspects of the recombinant live oral Vibrio cholerae vaccine strain CVD 103-HgR

The development of live attenuated vaccines, allowing for the safe and effective immunisation at mucosal surfaces, is a strategy of great interest for vaccinologists. The main advantage of this approach over conventional parenteral vaccines is the induction of strong mucosal immune responses, allowing targeting of the pathogen at the initial point of contact with the host. Further advantages include the ease of administration, high acceptance by vaccines, and relatively low production costs. Finally, well-characterised, safe and immunogenic vaccine strains are well suited as vectors for the mucosal delivery of foreign vaccine antigens and of DNA vaccines. However, such vaccines, when based on or containing genetically modified organisms (GMOs), are facing new and specific regulatory hurdles, particularly regarding the potential risks for humans and the environment. In this contribution we address selected aspects of the risk assessment of live attenuated bacterial vaccines covered in the course of the registration of vaccine strain CVD 103-HgR as a recombinant live oral vaccine against cholera.     

Nosocomial transmission of Mycobacterium tuberculosis from an extrapulmonary site.

OBJECTIVE: To assess the extent of nosocomial transmission and risk factors associated with tuberculin skin test (TST) conversions among healthcare workers (HCWs) exposed to a patient with genitourinary Mycobacterium tuberculosis. DESIGN: Retrospective cohort study of exposed HCWs. SETTING: A 275-bed community hospital in Middle Tennessee. PARTICIPANTS: A total of 128 exposed HCWs and the index patient, who required drainage of a prostatic abscess and bilateral orchiectomy and expired after a 27-day hospitalization. Disseminated tuberculosis was diagnosed at autopsy. METHODS: Contact tracing was performed on exposed HCWs. Logistic regression was used to identify independent risk factors associated with TST conversion. RESULTS: A total of 128 HCWs were exposed to the index patient. There was no evidence of active pulmonary tuberculosis throughout the patient's hospitalization; TST conversions occurred only among HCWs who were exposed to the patient during or after his surgical procedures. A total of 12 (13%) of 95 exposed HCWs who were previously nonreactive had newly positive TST: 6 of 28 nurses, 3 of 3 autopsy personnel, 2 of 17 respiratory therapists, and 1 of 12 surgical staff. By logistic regression, irrigation or packing of the surgical site was the only independent risk factor associated with TST conversion among nurses (odds ratio, 9; 95% confidence interval, 1.2-67; P=.03). CONCLUSION: Manipulation of infected tissues of the genitourinary tract can result in nosocomial transmission of tuberculosis.     

Nosocomial pertussis in healthcare workers from a pediatric emergency unit in France.

OBJECTIVE: After pertussis was diagnosed in July 1997 in a 55-year-old nurse (case) from a pediatric emergency unit who had a respiratory illness and paroxysmal cough for 5 weeks, an epidemiological investigation was initiated to determine if other healthcare workers (HCWs) from the same unit also had pertussis. DESIGN: Interviews were conducted to assess symptoms occurring in the previous months. Two sera were collected 2 to 3 months apart for 59 of 61 HCWs of the unit. The IgG response to pertussis toxin was determined using Western blot assay. SETTING: Pediatric emergency unit (61 HCWs) of a 2,500-bed university hospital. RESULTS: There was a total of 10 (5 confirmed and 5 probable) cases of pertussis identified in this outbreak. Nine HCWs (15%) had results suggesting recent or acute pertussis. To avoid transmission to patients and other HCWs, all HCWs with cough were treated for 14 days with erythromycin, and those having acute cough were given a 5-day sick leave. Despite these measures, a new acute pertussis case was identified in a 41-year-old nurse, with a positive culture from nasopharyngeal aspirates. Thus, all HCWs in the unit were prescribed spiramycin for 10 days to prevent any further spread of pertussis. CONCLUSION: Pertussis should be considered a threat to HCWs who are in contact with children. For HCWs, diagnosis of pertussis should be made on a clinical basis, giving greater importance to sensitivity of diagnosis criteria, and on early bacterial identification by culture of the organism or by polymerase chain reaction. RECOMMENDATIONS: In case of pertussis in an HCW, all staff in the unit who have had unprotected and intensive contact with that person should be provided with macrolide treatment to stop any transmission to colleagues and to young patients. Furthermore, the possibility of providing these HCWs with acellular pertussis vaccines warrants further investigation.     

两种流行性乙型脑炎疫苗基础免疫的血清抗体观察

为考察流行性乙型脑炎 (乙脑 )减毒活疫苗和灭活疫苗的免疫效果和安全性 ,在新沂市和邳州市分别对 14 1名和 99名无乙脑疫苗接种史的 12～ 2 4月龄儿童 ,分别用乙脑减毒活疫苗和灭活疫苗进行基础免疫 ,在免疫前和免疫后 1个月采血用反向被动凝集抑制试验检测血清抗体。结果 :14 1名经减毒活疫苗免疫的儿童 ,抗体阳性率由免疫前的 2 2 70 %上升至免疫后的 87 2 3 % ,GMT由 1∶12 60上升为 1∶46 13 ;99名用灭活疫苗初免 2针的儿童 ,抗体阳性率由 13 13 %上升至 67 68% ,GMT由 1∶11 83上升至 1∶2 2 5 3。对免疫前抗体阴性的儿童 ,分别注射乙脑减毒活疫苗和灭活疫苗后 ,抗体阳转率分别为 83 49%和 62 79%。两种疫苗的安全性均好 ,接种后仅 17人 ( 0 0 7% )有轻度发热 ,11人 ( 0 0 4% )出现局部红肿。而减毒活疫苗出现反应的人数又少于灭活疫苗。本次观察表明 ,乙脑减毒活疫苗的免疫效果明显高于灭活疫苗 ,安全性好 ,接种次数少 ,适宜于推广使用。