Systematic toxicology investigation indicates that 3.1% of SDs are COC-related and are mainly due to cardio-cerebrovascular causes. Left ventricular hypertrophy, small vessel disease, and premature coronary artery atherosclerosis, with or without lumen thrombosis, are frequent findings that may account for myocardial ischaemia at risk of cardiac arrest in COC addicts.

The reactions to and antigenicity of two human-rhesus rotavirus (RRV) reassortants (human rotavirus strain D x RRV and human rotavirus strain DS1 x RRV) with the VP7 neutralization specificity of a serotype 1 or serotype 2 rotavirus were evaluated in a placebo-controlled double-blind trial in 116 1to 5-month-old infants in Caracas, Venezuela. The children were randomly divided into five groups to receive orally the following inocula: (i) 104 PFU of D x RRV reassortant; (ii) i04 PFU of DS1 x RRV reassortant; (iii) 1 PFU of RRV; (iv) 5 x 103 PFU of D x RRV and 5 x 103 PFU of RRV; and (v) placebo. The children were examined daily for 7 days following vaccine administration; 8 to 26% of the vaccinated infants developed a mild febrile reaction which in most cases lasted only 1 day. Seroresponses to rotavirus were observed in 39 to 65% of the vaccinees by plaque neutralization assay and in 57 to 88 % by an immunoglobulin A enzyme-linked immunosorbent assay. Vaccine shedding was detected in 53 to 86% of the vaccinees. Analysis of neutralization antibody responses indicates that the VP4 protein represents an important component of the response induced by the vaccines.

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I studies of an oral quadrivalent rotavirus vaccine were conducted in 130 Venezuelan infants 10 to 20 weeks of age. The vaccine consists of a mixture of equal amounts of rhesus rotavirus (RRV) vaccine (serotype 3 [VP7]) and each of three human rotavirus-RRV reassortant strains: D x RRV (serotype 1 [VP7]), DS1 X RRV (serotype 2 [VP7]), and ST3 x RRV (serotype 4 [VP7]). Three different doses of the quadrivalent vaccine (0.25 x 104, 0.5 x 104, and 104 PFU of each component) were evaluated sequentially for safety and antigenicity in placebo-controlled, double-blind trials. Starting the day after vaccination, the infants were monitored by daily home visits for 7 days. Only minor reactions were observed during this period; these were limited to mild transient febrile episodes which began day 2 or 3 after vaccination and lasted 1 to 2 days in 15 to 30% of the infants. Serological studies demonstrated that 68 to 96% of the infants developed a rotavirus serum immunoglobulin A response following vaccination. However, when tested by plaque reduction neutralization assay against individual human rotavirus serotype 1, 2, 3, or 4, the response rates ranged from 4 to 23% with the low dose, 21 to 33% with the medium dose, and 32 to 58% with the high dose. Most (73 to 79%) infants developed neutralizing antibodies to RRV following administration of each dose schedule. Vaccine virus shedding was analyzed by utilizing tissue culture isolation of virus from stool. All of the infants who received the lower or medium dose and 89% of those fed the high dose shed one or more components of the vaccine. Analyses of rotavirus serotypes isolated from the stool of infants who received the 0.25 x 104-PFU dose revealed that DS1 X RRV was the most commonly shed vaccine component, followed by RRV, D x RRV, and ST3 x RRV in that order.

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