Pneumococcal antibody levels one decade after immunization of healthy adults.

The authors investigated the persistence of anticapsular pneumococcal antibodies in 21 subjects one decade after administration of a single dose of a polyvalent pneumococcal polysaccharide vaccine. Fourteen vaccinees received a hexavalent vaccine composed of the polysaccharides of capsular types 1, 3, 4, 7F, 8, and 12F; four vaccinees received an octavalent vaccine consisting of these six polysaccharides and also those of capsular types 14 and 19F; and three vaccinees received a nonavalent vaccine that also included type 5 capsular polysaccharide. Antibody was measured by radioimmunoassay. The authors detected persistently elevated anticapsular antibody levels among more than one half of vaccinees who developed a significant rise in antibody 1 month following immunization one decade after administration of pneumococcal polysaccharide vaccine when these levels were compared to prevaccine levels for pneumococcal capsular types 4, 7F, and 8. This finding was not the case with pneumococcal types 1, 3, 12F, 14, and 19F; less than two fifths of vaccinees maintained increased levels of anticapsular antibody to these types one decade after administration of pneumococcal vaccine. Geometric mean anticapsular antibody levels for types 7F and 8 only were significantly higher one decade after vaccine administration compared with the levels before immunization (t-test, p less than 0.01).

Reactivity and antibody responses of volunteers given two or three doses of pneumococcal vaccine.

Pneumococcal antibody responses and adverse reactions were assessed in 12 healthy volunteers who received either two (10 volunteers) or three (2 volunteers) doses of pneumococcal polysaccharide vaccines at 1 or 2 year intervals. The volunteers were given hexavalent (types 1, 3, 4, 7F, 8, 12F) octavalent (types 14, 19F added) nonavalent (type 5 added), and tridecavalent (types 6A, 6B, 9N, 18C, 23F added; type 5 removed) pneumococcal vaccines. Local and systemic reactions following any of the vaccines, either first, second, or third doses, were low, and these were mild; fever did not occur. Twelve volunteers received types 1, 3, 4, 7F, 8, and 12F in two doses of vaccine, and four volunteers received types 14 and 19F in two doses of vaccine. Primary immunization induced significant antibody rises to these antigens in most volunteers, but a second dose of vaccine did not further increase antibody levels to the same antigens; when it also contained new antigens, antibody rises usually developed to these antigens. Although the data are limited to detailed studies of only 12 persons, the results suggest that additional studies of this issue would seem appropriate.

Long-term persistence of antibody following immunization with pneumococcal polysaccharide vaccine.

Thirty-seven healthy volunteers who received a pneumococcal polysaccharide vaccine were tested 4, 5, or 6 years after immunization for circulating type-specific pneumococcal antibody by radioimmunoassay of their sera. Each volunteer was immunized with one of four different pneumococcal vaccines containing 50 micrograms of each of 6, 8, 9, or 13 capsular polysaccharides; a few volunteers received octavalent or tridecavalent pneumococcal vaccines combined with bivalent influenza virus vaccine in a single syringe. Four years after immunization, the mean antibody level was 90% of the level achieved 4 weeks after vaccination. Among volunteers tested 5 years after immunization (including three 6 years after vaccination), the mean antibody level was 76% of that 4 weeks after inoculation. These findings confirm the long-term persistence of vaccine-induced type-specific pneumococcal antibodies and suggest that the interval between repeated doses of pneumococcal vaccine should be at least 5 years.

Model of the supine human body and its reactions to external forces.

Mechanical impedance and vibration transmissibility measurements were conducted on supine humans using sinusoidal vibrations. The frequencies tested were 1-20 Hz with a constant acceleration amplitude of 0.3 G. The tests were repeated with 4.54 kg pure mass placed on each segment. Both results were used to calculate a multi-degree-of-freedom lumped parameter model. The nonlinear reactions of the body are revealed by comparing the model parameters under "no load" and "load" conditions. When the results are compared with impedance measurements conducted under sustained acceleration, it becomes obvious that the thorax, due to its anatomical design, reacts differently from the remaining body parts.

Role of maternal antibody in pneumonia and bronchiolitis due to respiratory syncytial virus.

Fifteen infants with pneumonia caused by respiratory syncytial virus (RSV) and 19 infants with bronchiolitis caused by RSV were studied for the influence of homologous, circulating neutralizing antibody on the severity of their illness. All infants were under nine months of age. Although maternal neutralizing antibody did not prevent infection with RSV and illness, the severity of pneumonia caused by RSV was inversely related to the level of neutralizing antibody. The severity of bronchiolitis caused by RSV was unrelated to maternal antibody levels. Chest roentgenograms showed pneumonia to be slightly more severe than bronchiolitis. Neither the severity of illness nor the presence of maternal neutralizing antibody was related to the development of complement-fixing antibody.