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At least 253 records · Page 14Linked to original sources

PubMed1989

[Seroconversion with trivalent Sabin vaccine in children less than four years of age].

A group of 58 children under 4 years old, were vaccinated with trivalent oral poliovirus vaccine Sabin (OPV), in two sanitary areas of Chiapas, Mexico. The complement of procedures for the maintenance of the cold chain, and the changes in the potency of the vaccine prior and after the vaccination were evaluated. Nurses got a blood sample of 3cc and other one, four weeks after vaccination in order to evaluate the seroconversion rate attributable to Sabin vaccine, which was analyzed through neutralization serologic test. Moreover the investigation team got a sample of feces one day prior to vaccination and other one every week in the following three weeks to vaccination date in order to isolate the poliovirus in the feces of the children. The high pre-vaccination seropositivity suggests that in these areas exist a wide circulation of poliovirus, which probably were vaccine viruses and in less proportion wild viruses. The seroconversion rates were low for the three types of poliovirus, nevertheless 83% of the children had at least one of the three possibilities of seroconversion: unique, double or triple. Children with pre-vaccine seropositive probably had a secondary immune response.

Antibodies, Viral↗

PubMed1989

Clinical study of tetanus neonatorum.

Seventy six cases of neonatal tetanus were studied. There was preponderance of males. Short incubation period, short period of onset, low birth weight, presence of fever and tachycardia were associated with a poor prognosis. The cases were divided into 2 groups of 46 and 30. First group was given TIG while second group was given ATS. All other therapies were kept identical. Mortality rate in two groups was 97.5% and 96.5%. Corrected mortality due to tetanus per se was 22.5% and 28.5% (p-0.5). Fifteen cases (32.7%) and 12 cases (40%) in group A & B respectively were born to mothers who had already received one to three doses of tetanus toxoid. The potency of the vaccine should be ensured before it is administered to mothers, through proper maintenance of cold chain. It is concluded that TIG is not superior to ATS in managing moderate and severe grade cases.

Female↗

PubMed1989

Measles prevention and control in emergency settings.

Outbreaks of measles continue to be a common occurrence among refugee and famine-affected children in emergency relief camps. Extremely high measles-associated mortality rates have been reported from refugee camps--where undernutrition is common--in several countries over the past 10 years. Mortality from measles is, however, preventable, and immunization against the disease is a high priority in emergency relief programmes, second only in importance to the provision of adequate food rations. All children aged 6 months to 5 years should be immunized with measles vaccine as soon as they enter an organized camp or settlement. Should supplies of measles vaccine be inadequate, children in feeding centres, or those otherwise identified as undernourished, are the top priority for immunization. The occurrence of measles in a camp is not a contraindication to conducting an immunization campaign. Strong coordination by a designated lead agency is needed if such campaigns are to be successful; however, cooperation with the local expanded programme on immunization is essential to ensure that existing cold chain equipment, training protocols, and management manuals are used. If additional equipment is necessary, a complete immunization kit developed by the Office of the United Nations High Commissioner for Refugees, the World Health Organization, and Oxfam can be procured from Oxfam headquarters in the United Kingdom. Vitamin A supplements should be given routinely at the time of measles immunization in situations where malnutrition is severe. Mortality and morbidity in children with clinical measles can be reduced by administering high doses of vitamin A.

Child, Preschool↗

PubMed1988

Pox viruses as eukaryotic cloning and expression vectors: future medical and veterinary vaccines.

It was proposed at the beginning of this article that the use of poxviruses as expression vectors provided a means of optimizing the conditions and prerequisites of vaccination and of elucidating a number of the associated problems. These advantages will now be summarized. Vaccinia virus recombinants carrying one or more multiple foreign genes have been shown to induce a sufficient immune response to that antigen in laboratory animals to protect against subsequent challenge by the infectious agent. In those animals tested the duration of immunity has been long-lasting with no apparent detrimental side-effects. Vaccinia virus is very stable in normal environmental situations and no cold-chain is required in the distribution network. There is no evidence for genetic instability of the vaccinia 'carrier' strain nor of loss of the inserted genetic elements. The vaccine is administered intradermally and it is proposed that one inoculation will be sufficient to induce immunity to multiple disease antigens; however, re-inoculation at a later time with the same or new antigenic determinants is not precluded. The efficiency of vaccinia virus as the vaccine strain used to eliminate the disease of smallpox with minimal side-effects is well documented. The recent studies described here on the development of vaccinia as a viral vector confer other advantages. Since the expression of the inserted genetic element is under vaccinia virus control, different levels of expression can be engineered by substituting the promoter sequence placed proximal to the insert. This leads to the possibility of high levels of expression when required for a single antigen or more modulated levels when multiple foreign antigens are expressed and 'genetic overload' could become a problem. Much work remains to be done on the body's immune response to this proposed genetic intrusion. The ability to insert large amounts of genetic information without disrupting virus replication and assembly indicates a great degree of flexibility in the genome strategy of the virus. This may indicate that the replication system can be further disrupted to eliminate or modify those sequences coding for virulence and wide host range to make the poxvirus vector as safe as possible for vaccine use. One of the reasons traditional vaccine strategy has failed for some virus groups is the degree of variability found in virus strains in nature. Influenza viruses are a good example, as are the bluetongue virus group, rotaviruses and bunyaviruses.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1984

Field trial of a heat-stable measles vaccine in Papua New Guinea.

In Papua New Guinea, consideration has been given to the introduction of measles vaccination, and a trial was conducted to determine the optimum age for vaccination and the suitability of a heat-stable measles vaccine (Rimevax) for countrywide use. As much of the vaccination programme is carried out by MCH teams on foot patrols, the trial was designed to determine immunogenicity of the vaccine after being transported and used for a week in a standard issue vaccine Esky by MCH staff. A study of the relevant literature having indicated 9 months as the probable best minimum age for measles vaccination, younger children were not included. The study was carried out on 313 infants and children aged nine to 24 months. An overall seroconversion rate of 96.6% was achieved using initially potent vaccine kept under field conditions for up to 102h. Ninety-seven percent of the vaccinees less than 11 months and 15 days of age seroconverted, as did all 15 children who were less than 70% of the Harvard standard weight for age. All 35 children who had seroconverted and who were retested six months after vaccination had detectable measles antibodies in their serum. Parental recollection of past measles infection was found unreliable as was reporting of post-vaccination reactions by parental recall since the incidence of reported 'reactions' in initially seronegative and seropositive vaccinees were similar. It is concluded that use of this heat-stable vaccine is possible with existing cold chain facilities in PNG and that infants can be vaccinated from the age of 9 months.

Antibodies, Viral↗

PubMedDate not supplied

Current impact of measles in Latin America.

The importance of measles as a public health problem and its impact on mortality in children has been recognized for many years in Latin America. This problem was analyzed in detail in 1961 at the International Conference on Measles Immunization held in Bethesda, Maryland. However, despite the availability of good vaccine since 1963, only two countries--Chile and Cuba--have achieved the goal of the 10-year health plan for the Americas, which was a specific mortality rate of less than one death per 100,000 population. The reasons for this epidemiologic situation are mainly three: inability of the health-care infrastructure of the countries to reach the susceptibles and maintain effective national coverage in the vaccination programs, inadequate cold chain, and the high cost of vaccine. This situation is beginning to change with the implementation of the World Health Organization Expanded Programme on Immunization and the help and catalytic power of the Pan American Health Organization. Because of this we are optimistic about the success the measles vaccination programs may achieve during the 1980s.

Adolescent↗

PubMedDate not supplied

[Development of an operational immunization programme (author's transl)].

Following the severe 1974 W. H. O. warning, many countries want to develop an expanded programme of immunization during the period extending till 1990, to control 6 major diseases: diphtheria, tetanus, poliomyelitis, pertussis, measles and TB. No single programme can be proposed as the economic, epidemiological and structural problems differ according to countries and regions. C. Fillastre suggests a methodology to be used in the assessment of the initial situation with regard to existing epidemiological data, immunizations against the afore mentioned diseases, vaccines health structures (cold chain) and staff. The implementation of the supervision of material and staff and of an assessment system, allowing programme changes at any time on the basis of improvements achieved is mandatory.

Child↗

PubMed1978

The need for quality control in the developing countries.

In the developing countries there is a need for greater activity in the quality control of vaccines used in immunization programmes. The establishment of a quality control facility can give assistance not only in the checking of vaccines at the time of release, but also in monitoring the efficacy of the cold chain. Furthermore, the antibody responses of the local child population to the vaccines can be measured. Quality control should be established before vaccine manufacturer, therefore, and the economics of importing vaccine in the bulk concentrated form with dilution, blending and filling locally is worthy of consideration.

Antibodies↗

PubMed1994

The efficacy of Japanese encephalitis vaccine in Henan, China: a case-control study.

A population based case-control study to evaluate Japanese encephalitis (JE) vaccine efficacy was carried out in Gusi County, Henan Province, China from June to September in 1991. This study showed that the JE vaccine had a strong protective effect. The estimate of the vaccine efficacy was 78% (95% CI = 16-94%). An unimmunized child was at 4.54 times greater risk of developing JE than were fully immunized children during the study period. The present study may have underestimated the vaccine efficacy due to evaluation based on routine vaccination which might have been affected by vaccination management and the local cold chain system.

Antibodies, Viral↗

PubMedDate not supplied

Measles in southern Ghana: 1985-1993.

Measles continues to be a significant cause of morbidity and mortality among children in Southern Ghana although at a much lower level than a decade earlier. The major indications for measles admissions and the mortality associated factors of pneumonia, malnutrition, and diarrhea complicated by dehydration, however remain the same. The majority of measles admissions were in children without primary immunization resident in the more densely populated inner city of Accra and the peri-urban areas inhabited by lower-income recent immigrants. Our data show uncomfortable increases in the number of children aged 3-8 months as well as school age children (> or = 60 months), thus reopening the perennial discussion on the measles immunization programme i.e. what to do with younger infants with doubtful maternally-derived protection as well as the children who have missed their primary immunization at 9 months or those with immunization failure. The advantages of the 2-dose measles immunization programme need urgent consideration by national programme directors in African countries. The second dose is especially advocated to address the attendant problems of the cold chain system, vaccine efficacy, vaccine failure and diagnostic errors as older school-going age children.

Child↗

PubMed1993

Epidemiological evaluation of oral polio vaccine efficacy in Cairo.

A case-control study was conducted between November 1992 and May, 1993 to assess the effectiveness of routine oral polio vaccine (OPV) immunization against paralytic poliomyelitis among children aged 1-5 years in Cairo city. Cases of paralytic poliomyelitis at Imbaba Institute of poliomyelitis and Ain-Shams Pediatric Hospital fulfilling the study criteria were obtained. The diagnosis of cases was based on clinical grounds. Age and sex-matched controls were recruited concurrently from patients admitted for reasons other than poliomyelitis. There were 55 cases of poliomyelitis. Vaccination status of cases and controls was ascertained by asking the mothers through interviewing using a questionnaire that had been developed for the purpose of the study. Vaccine efficacy (VE) was 86% (95% CI: 39-97%) and 92% (95% CI: 64-98%) for 3 and 4 doses of OPV respectively. For a vaccine like OPV with the potential of near 100% VE after 3 doses, the estimated level of protection (86%) is considered low especially when we realize the enormous efforts carried out by Ministry of Health and UNICEF in Egypt for upgrading the cold-chain. Higher figures of VE are supposed to be achieved if we are going to meet the challenge of poliomyelitis eradication by the year 1994. Potential biases in study design were also discussed.

Case-Control Studies↗

PubMedDate not supplied

Vaccine storage in the physician's office: a community study.

BACKGROUND: A survey was conducted of 26 physician offices and the County Health Department to determine the quality of vaccine storage. METHODS: All refrigerators were examined for secure electrical supply, firmly shut door, storage of inappropriate items, and expired vaccines. A maximum-minimum thermometer was then placed in the middle of the storage area for 24 hours, and temperatures were recorded. RESULTS: Of the 27 sites, only two had refrigerator temperatures in which both maximum and minimum temperatures fell within the acceptable range of 2 degrees to 8 degrees C. Sixty-three percent fell below minimum, 59 percent were above maximum, and 93 percent fell either below or above or both. Eight of the offices had a designated cold chain monitor, but there was no correlation with appropriate monitoring and storage of vaccines. Nine of the offices had permanent thermometers, but no correlation could be found between these sites and appropriate storage temperatures. CONCLUSIONS: A majority of vaccines in the community have been exposed to conditions that could reduce or destroy their potency. Physicians must educate their personnel in proper storage techniques of vaccines to ensure the potency of these vaccines.

Child↗

PubMed1994

[Study on factors affecting vaccination effect of poliomyelitis vaccine].

We carried out this 1:2 matched case-control study in some counties and townships in Guangxi, Henan and Jiangsu provinces from June to October in 1992 to find the risk factors of poliomyelitis incidence among fully vaccinated children. Then we processed the collected data with individual and multiple condition logistic regression analysis and found the risk factors of poliomyelitis incidence among fully vaccinated children included two kinds, the community factors and the individual factors. The community factors which related to the cold chain and health services. They are the special risk factors for fully vaccinated children. The individual factors are the common risk factors for both fully vaccinated and unvaccinated children. In addition, children received five or more doses of TOPV was a favorable factor against poliomyelitis. It was showed that we must improve vaccination quality while rising TOPV coverage continually.

Case-Control Studies↗

PubMedDate not supplied

[Integration of the Expanded Program on Immunization into primary health care: examples of Benin and Guinea].

Since 1986, two West African countries have been delivering immunizations within the framework of reorganized peripheral health systems. This revitalization is based on strategies which are implemented by an increasing number of African countries under the name "Bamako Initiative". It aims at providing universal access to a minimum package of maternal and child health priority interventions starting with immunizations, pre and perinatal care, oral rehydration for diarrhoea, treatment of malaria and acute lower respiratory infections. Within this package, immunization has been given high priority. Several strategies aimed at improving immunization coverage have been implemented: services have been reorganized so that any child or woman making contact with the health system receives immunization if needed. Health information systems have been revised so as to allow for active individual follow up and better management of health centre resources. Health staff have been given training in management and a biannual monitoring/microplanning process at health centre level has been introduced. The goal of monitoring is to enable health personnel to identify the obstacles to attaining optimum coverages with the priority interventions and to select locally appropriate corrective strategies. Health centres have also been provided with a motorcycle allowing for regular outreach activities. To cover the running costs of the services (mainly restocking of drugs, running and maintenance of the cold chain and the motorbike, and staff incentives), financial contribution from local communities have been sought through a fee-for-treatment system. Prices have been set at an affordable level by limiting the number of drugs to a minimal list purchased under generic names by international tendering procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Benin↗

PubMedDate not supplied

Can we agree on a prescription? A view from the perspective of the developing countries.

There are serious obstacles, particularly on the African Continent, to the application of the official strategy for eradication of poliomyelitis. Outbreaks in countries where a potent OPV was used keep raising the question of its efficacy in routine programs. Based on the South American strategy, 200 million doses of OPV are needed for the 11 million children born each year. Such quantities of vaccine can hardly be procured for the rest of the world. Organization of vaccination campaigns will be competing with other public health programs. Studies in Africa and in the Middle East have shown the good performance of one or two doses of eIPV combined with DTP. At the current price of the quadruple vaccine DTP-eIPV, its cost effectiveness not only in money, but in practical terms, especially for the inventory, the cold chain, and the delivery, would be extremely attractive.

Africa↗

PubMed1996

Problems encountered in the delivery and storage of OPV in an African country.

Southern Africa may be developing into another poliomyelitis-free zone. Apparent control has been achieved in spite of suboptimal coverage, absence of supplementary strategies, vulnerability to importation and major outbreaks of other waterborne pathogens such as typhoid. A number of serological studies have demonstrated significant susceptibility, especially in rural populations, and studies of three southern African epidemics have shown, in two of them, that epidemics can occur in spite of relatively high levels of serological immunity and vaccine coverage if the burden of virus is sufficiently great. Two studies comparing vaccine coverage to serological immunity have shown that only 78% of fully immunized children in one study and 81% in the other study developed antibodies to all three types of poliomyelitis. In two investigations where vaccine samples were recalled for potency testing from peripheral clinics, almost a half and almost a third, respectively, of vaccine vials had titres below WHO recommended cut-off limits. Major logistical and organizational difficulties in storage and transport of vaccine under cold chain conditions were present in South Africa. These are being rectified and energetic attempts are being made, aided by a strong governmental commitment to improve vaccine coverage and to institute mass immunization campaigns. Nevertheless the need for the development of a more stable OPV for developing and tropical countries still remains a major objective in the global eradication of poliomyelitis.

Animals↗

PubMed1996

Stabilising oral poliovaccine at high ambient temperatures.

The oral poliovaccine strains lose infectivity when they are stored above refrigerator temperatures. These losses increase rapidly at the high temperatures encountered in tropical countries, thus causing problems if the cold chain is inadequate. Attempts to minimise these losses have generally relied on the addition of salts such as MgCl2. In this paper we show that the fail in infectivity, which is due to the hydrolysis of the genomic RNA by the RNA polymerase within the virus particle, can be greatly inhibited by the suppression of this enzymatic activity. This can be achieved simply by reducing the pH below 7.

Capsid↗

PubMed1996

Analysis of vaccine stability.

The complexity of vaccines creates a unique formulation challenge. Vaccines may consist of one or more types of antigenic component including live attenuated or killed viral or bacterial particles, polysaccharides, proteins, polynucleotides and particle conjugates. In addition, other excipients such as adjuvants may be present. Not only must the chemical and structural integrity of the various components be maintained, but immunogenicity must be ensured. The inherent lability of vaccines can critically limit their distribution, administration, and efficacy in parts of world where it is difficult to maintain a cold chain. Combination with other vaccines and oral administration may also compromise vaccine stability. Successful vaccine stabilization strategies include both empirical efforts to screen and identify appropriate stabilizers and environmental conditions and more rational approaches toward developing an understanding of the causes and mechanisms of vaccine inactivation. In principle, by elucidating the conformational and chemical pathways of macromolecular inactivation, more rational strategies to minimize their occurrence can be adopted. This presentation will review the application of classical techniques such as viral plaque assays to identify vaccine stabilizers by empirical testing. The potential of using various biophysical techniques (both hydrodynamic and spectroscopic methods) to characterize the physicochemical stability of purified vaccine preparations (Hepatitis A and B) is also explored.

Antigens, Viral↗