Immunization surveillance after

After reaching the lymph nodes, CD4+ cells are rapidly infected and replication of the virus continues. During the initial phase of infection, the virus is spread throughout the body via blood that contains many viral particles. The flu-like symptoms are first observed in about 70% of the patients 2-A weeks after HIV infection. At this stage, HIV titer is reduced due to the development of virus-specific CD8+ cells and due to humoral immune response, which generally causes a return to the normal numbers of CD4+ cells. As the HIV continues to replicate, a person may stay free of HIV-related symptoms for years. The high rate of mutation makes it impossible for the body to completely eliminate the HIV. Independent of mutation, certain subsets of HIV-recognizing killer T cells are not present or lack optimal function, and there is an inhibition of IFN secretion and cytotoxic T-cell activity due to impairment in the function of CD4+ cells. The HIV is also protected from immune surveillance when it hides within the chromosomes of the infected cells. 

Immunosuppression.The immune system has a role in suppressing cancers (immune surveillance). A wide range of cancers develop in immunosuppressed patients, e.g after organ transplantation and cancer chemotherapy. 

Host resistance factors may also be important in metastatic cell trafficking. For instance, immune surveillance may reduce the number of metastatic cells in the bloodstream, resulting in a reduced accumulation of cells in a target organ. Likewise, even after surgical removal of the primary tumor, a substantial number of viable tumor cells can be detected in the circulation. However, this... 

The Vaccine Adverse Event Reporting System (VAERS) is a national vaccine safety surveillance program co-sponsored by the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA). VAERS collects and analyzes information from reports of adverse reactions after immunization. Anyone can report to VAERS, and reports are sent in by vaccine manufacturers, health care providers, and vaccine recipients and their parents or guardians. An example of the VAERS and instructions for completing the form are found in Appendix F. Any clinically significant adverse event that occurs after the administration of any vaccine should be reported. Individuals are encouraged to provide the information on the form even if the individual is uncertain if the event was related to the... 

From 1978 through 1990, the Centers for Disease Control and Prevention (CDC) and the Food and Drag Administration divided the responsibility for postmarketing surveillance of vaccines in the United States. FDA received reports of adverse events after vaccines were administered in the private sector events occurring after the administration of vaccines purchased with public funds were reported to the Monitoring System for Adverse Events Following Immunization. 

The WHO has recommended that individuals with clinical (symptomatic) AIDS or other clinical manifestations of HIV-infection should not receive BCG (108). The Global Advisory Committee on Vaccine Safety has noted that there has been repeated reference to local or disseminated BCG infection several years after BCG immunization in HIV-infected persons (109). However, the Committee has not recommended a change in immunization policy (BCG immunization recommended in asymptomatic HIV-infected persons not recommended in symptomatic HIV-infected persons), but surveillance for BCG-immunized, HIV-infected persons should be continued for 5-7 years. 

Guillain-Barre syndrome (13) and polyradiculoneuritis (14,15) have rarely been reported. In a national surveillance study of GuiUain-Barre syndrome in the USA, 31 of 998 cases developed the illness within 8 weeks after immunization. Of these 31 cases, 5 had been immunized with DT or DPT vaccine (16). 

By 1988 it was possible to summarize the adverse effects reported after the distribution of over 1.8 million doses of plasma-derived hepatitis B vaccine (Table 1) (2). From 1982 onwards, the Centers for Disease Control, the Food and Drug Administration, and the manufacturers, Merck Sharp Dohme, had supported a special surveillance system to monitor spontaneous reports of reactions to plasma-derived hepatitis vaccine. During the first 3 years, about 850 000 persons were immunized. In all, 41 reports were received for one of the following neurological adverse events convulsion (n = 5), Bell s palsy (n — 10), Guillain-Barre syndrome (n = 9), lumbar radiculopathy (n — 5), brachial plexus neuropathy (n = 3), optic neuritis (n — 5), and transverse myelitis (n = 4). Half of these events occurred after the first vaccine dose. However, no conclusive causal association could be made between any neurological adverse event and the vaccine (3). 

Postmarketing surveillance data of adverse events after Japanese encephalitis immunization in Japan and the USA have been compared (7). The rates of total reported adverse events were 2.8 per 100 000 doses in Japan and 15.0 per 100 000 doses in the USA. In Japan, 17 neurological disorders were reported from April 1996 to October 1998 (0.2 per 100 000 doses), whereas in the USA there were no serious neurological adverse events temporally associated with Japanese encephalitis vaccine from January 1993 to June 1999. Rates for systemic hypersensitivity reactions were 0.8 and 6.3 per 100 000 doses in Japan and the USA respectively. 

Suspicions were expressed in the Mealey Publication s Drug and Medical Device Report that the Lyme disease vaccine LYMErix could cause an incurable form of autoimmune arthritis. It was hjrpothesized that blood concentrations of OspA after three doses of vaccine place vaccinees classified by genetic type HLA-DR4-I- at risk of developing treatment-resistant Ljme arthritis. The premarket trials for the vaccine were assessed by an independent advisory committee, which found no link between Ljme disease immunization and autoimmune arthritis (10). However, the committee stressed the need for long-term surveillance and further studies in those over 70 years and in children, and the effect of the vaccine in patients with chronic arthritis the possible development of autoimmunity deserves further study (11). After licensing of the vaccine, more than 1 rmlfion Americans received it and no unusual adverse effects were reported to the manufacturer (10). 

Data on adverse events reported to a passive provincial surveillance system have been evaluated after the mass immunization with a polysaccharide meningococcal vaccine of 1 198 751 people aged 6 months to 20 years in Quebec. A total of 118 reports of severe adverse events were selected. The most frequent were allergic reactions (9.2 per 100 000 doses), followed by few neurological reactions (0.5 per 100 000 doses) and very few anaphylactic reactions (0.1 per 100 000 doses). There were no reports of long-lasting sequelae or of encephalopathy, encephalitis, or meningitis (15). 

Terms and definitions used in surveillance programs of adverse events and adverse ejfects after immunization... 

An epidemiological and statistical method based on linkage of routinely available computerized hospital admission records with vaccination records has been described by Farrington (20). This active surveillance method has been used to assess the attributable risk of convulsions after DTP and MMR immunization and to investigate the relation between MMR vaccine and idiopathic thrombocytopenic purpura in children under 2 years of age in five districts in England. 

There are other national surveillance programs on adverse events after immunization, for example in Denmark, Germany, Sweden, the UK, Hungary developing countries such as India (SEDA-17, 363) and Brazil (SEDA-16, 367) have also aheady started to collect data on severe adverse events. 

Adverse events after immunization—the need for improved research, surveillance, and communication... 

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