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Background. Children 6 through 35 months of age are recommended to receive half the dose of influenza vaccine compared with older children and adults. Methods. This was a 6-site, randomized 2:1, double-blind study comparing full-dose (0.5 mL) trivalent inactivated influenza vaccine (TIV) with half-dose (0.25 mL) TIV in children 6 through 35 months of age. Children previously immunized with influenza vaccine (primed cohort) received 1 dose, and those with no previous influenza immunizations (naive cohort) received 2 doses of TIV. Local and systemic adverse events were recorded. Sera were collected before immunization and 1 month after last dose of TIV. Hemagglutination inhibition antibody testing was performed. Results. Of the 243 subjects enrolled (32 primed, 211 naive), datafor 232 were available forcomplete analysis. No significant differences in local or systemic reactions were observed. Few significant differences in immunogenicity to the 3 vaccine antigens were noted. The immune response to H1N1 was significantly higher in the full-dose group among primed subjects. In the naive cohort, the geometric mean titer for all 3 antigens after 2 doses of TIV were significantly higher in the 12 through 35 months compared with the 6 through 11 months age group. Conclusions. Our study confirms the safety of full-dose TIV given to children 6 through 35 months of age. An increase in antibody responses after full- versus half-dose TIV was not observed, except for H1N1 in the primed group. Larger studies are needed to clarify the potential for improved immunogenicity with higher vaccine doses. Recommending the same dose could simplify the production, storage, and administration of influenza vaccines.

Administering 2 separate vaccines for seasonal and pandemic influenza was necessary in 2009. Therefore, we conducted a randomized trial of monovalent 2009 H1N1 influenza vaccine (2009 H1N1 vaccine) and seasonal trivalent inactivated influenza vaccine (TIV; split virion) given sequentially or concurrently in previously vaccinated children.Children randomized to 4 study groups and stratified by age received 1 dose of seasonal TIV and 2 doses of 2009 H1N1 vaccine in 1 of 4 combinations. Injections were given at 21-day intervals and serum samples for hemagglutination inhibition antibody responses were obtained prior to and 21 days after each vaccination. Reactogenicity and adverse events were monitored.All combinations of vaccines were safe in the 531 children enrolled. Generally, 1 dose of 2009 H1N1 vaccine and 1 dose of TIV, regardless of sequence or concurrency of administration, was immunogenic in children ≥ 10 years of age; children10 years of age required 2 doses of 2009 H1N1 vaccine.Vaccines were generally well tolerated. The immune responses to 2009 H1N1 vaccine were adequate regardless of the sequence of vaccination in all age groups but the sequence affected titers to TIV antigens. Two doses of 2009 H1N1 vaccine were required to achieve a protective immune response in children10 years of age.NCT00943202.

BACKGROUND Influenza-virus hemagglutinin (HA) protein expressed in insect cells by recombinant baculovirus is a candidate influenza vaccine. METHODS In a randomized, double-blind trial conducted in 399 adults > or = 65 years of age, the efficacy of trivalent inactivated influenza vaccine (TIV) licensed for intramuscular injection was compared with that of trivalent baculovirus-expressed HA vaccine administered at doses of 15 microg, 45 microg, or 135 microg of each HA. RESULTS Compared with TIV, baculovirus-expressed HA vaccine was safe and induced better serum antibody responses to the H3 component when administered at doses of 45 microg or 135 microg of each HA. CONCLUSIONS Baculovirus-expressed HA is a safe and immunogenic influenza vaccine in elderly adults.

Persistent nontreponemal titers after treatment are common among patients with early syphilis. We retreated 82 human immunodeficiency virus–negative early syphilis participants who were serofast at 6 months using benzathine penicillin. Only 27% exhibited serological response after retreatment and after an additional 6 months of follow-up.

The authors conducted a 2-year, multicenter, double-blind, placebo-controlled efficacy field trial of live, attenuated, cold-adapted, trivalent influenza vaccine administered by nasal spray to children 15-71 months old. Overall, vaccine was 92% efficacious at preventing culture-confirmed infection by influenza A/H3N2 and influenza B. Because influenza A/H1N1 did not cause disease during the years in which this study was conducted, the authors sought to determine vaccine efficacy and correlates of immune protection against experimental challenge with 107 TCID50 of attenuated H1N1 (vaccine strain) by intranasal spray. Prechallenge assessments included serum hemaglutination-inhibiting (HAI) antibody and nasal wash IgA antibody to H1N1. Vaccine was 83% efficacious (95% confidence interval, 60%-93%) at preventing shedding of H1N1 virus after challenge. Any serum HAI antibody or any nasal wash IgA antibody was correlated with significant protection from H1N1 infection as indicated by vaccine-virus shedding, and high efficacy against H1N1 challenge was demonstrated.

Induction of CD8 + cytotoxic T cells is considered one of the important correlates for the protective efficacy of candidate human immunodeficiency virus type 1 (HIV-1) vaccines. To induce CD8 + cytotoxic T lymphocytes (CTLs) along with neutralizing antibody and CD4 + T cell help, a live canarypox virus construct expressing gp120, transmembrane gp41, the gag and protease genes, and sequences containing CTL epitopes in nef and pol was given simultaneously with, or followed by, rgp120 SF2. CD8 + CTLs were detected in 61% of volunteers at some time during the trial. Three to 6 months after the last immunization, the gene-specific responses were gag, 26/81; env, 17/77; nef, 12/77; and pol, 3/16. Simultaneous immunization with the canarypox vector and the subunit, beginning with the initial immunization, resulted in earlier antibody responses. In summary, a strategy of immunization with a canarypox vector expressing multiple genes of HIV-1 given with gp120 results in durable CD8 + CTL responses to a broad range of epitopes.

Among 2099 uninfected subjects in phase I and II trials of candidate AIDS vaccines, 23 were diagnosed with intercurrent human immunodeficiency virus type 1 (HIV-1) infection. High-risk sexual exposures accounted for 17 infections, and intravenous drug use accounted for 6. Four subjects received placebo, 13 received a complete immunization schedule (> or = 3 injections), and 6 were partially immunized (< or = 2 injections). There was no significant difference between vaccine recipients and control groups in incidence of HIV-1 infection, virus load, CD4 lymphocyte count, or V3 loop amino acid sequence. In summary, 19 vaccinated subjects acquired HIV-1 infection during phase I and II trials, indicating that immunization with the products described is < 100% effective in preventing or rapidly clearing infection. Laboratory analysis suggested that vaccine-induced immune responses did not significantly affect the genotypic or phenotypic characteristics of transmitted virus or the early clinical course of HIV-1 infection.

Prospective surveillance of Haemophilus influenzae type b (Hib) disease has been done since 1981 in two high-risk populations, White Mountain Apaches and Navajos. The attack rate in children less than 5 years of age is 5-10 times higher than in the general US population. Three vaccines were evaluated. Unconjugated Hib capsular polysaccharide produced lower antibody responses in 18- and 24-month-old Apache infants than in white infants. HbOC (Hib oligosaccharide covalently linked to the nontoxic mutant diphtheria toxin CRM197) produced low antibody responses in Navajo infants after one or two doses but induced responses similar to those in whites after three doses. The responses of 18-month-old Navajos to HbOC were lower than those of whites, but most achieved protective levels. PRP-OMP (Hib capsular polysaccharide linked to the outer membrane protein complex of Neisseria meningitidis) produced good immune responses in 2-month-old Navajo and Apache infants after a single dose. This vaccine was greater than 90% efficacious in protecting Navajo infants from Hib disease when given at 2 and 4 months of age. Even a single dose achieved a high protective efficacy.

A human hyperimmune globulin termed bacterial polysaccharide immune globulin (BPIG) has been prepared from plasma donors immunized with Haemophilus influenzae type b (Hib), pneumococcal, and meningococcal vaccines. At a dose of 0.5 ml/kg, BPIG increased levels of antibody to Hib by greater than 0.15 microgram/ml within 4-6 h and by 2-4 micrograms/ml at 72 h. Thereafter, antibody declined, with a mean half-life of 27 days. BPIG treatment of Apache infants did not impair their active antibody responses to concurrently administered diphtheria-tetanus-pertussis or Hib oligosaccharide-diptheria CRM197 conjugate vaccines. In high-risk Apache infants, BPIG given at 2, 6, and 10 months of age provided significant protection from invasive Hib infection during infancy. Thus, BPIG may have utility in the prevention of Hib infections in high-risk patients who cannot be immunized adequately with Hib conjugate vaccines.

A double-blind, randomized, placebo-controlled trial was conducted to evaluate the safety and efficacy of a rhesus rotavirus vaccine and RIT 4237, a bovine rotavirus vaccine, in a Navajo population. Infants aged 2-5 months were randomized to receive one dose of either 10(4) pfu of the rhesus rotavirus vaccine or 10(8) pfu of the RIT 4237 vaccine or placebo. Eleven (10.2%) of 108 infants in the rhesus vaccine group, 11 (10.4%) of 106 in the RIT 4237 group, and 9 (8.4%) of 107 in the placebo group experienced rotavirus diarrhea during the follow-up period of 17 months. Thus, in this population, neither vaccine was efficacious in preventing rotavirus diarrhea.