Assessment of elicited antibody responses, clinical reactions and transmissibility of WRL 105 live influenza vaccine

The spread and persistence of influenza viruses in normal and cyclophosphamide-treated mice

The persistence and extrapulmonary spread of three strains of influenza virus, the mouse neuro-adapted A/NWS virus, the wild-type strain A/Victoria/75, and a recombinant virus RIT4050, bearing surface antigens derived from A/Victoria/75, were studied in both normal and cyclophosphamide-treated CBA mice following either intranasal or intracerebral inoculation. All three viruses showed increased lethality in mice in the presence of cyclophosphamide but exhibited distinctive patterns of replication and spread. The recombinant virus RIT4050 showed a reduced ability to replicate, persist, and spread in CBA mice compared to either A/NWS or A/Victoria/75 viruses, and in general, the A/NWS virus persisted to a greater extent than the A/Victoria/75 virus in both normal and treated mice. However, in the presence of cyclophosphamide, no extrapulmonary spread of A/NWS virus was observed. The reasons for the differences are discussed.

Studies in man with cold-recombinant influenza virus (H1N1) live vaccines

Two cold-recombinant influenza A (H1N1) viruses were tested in several groups of human volunteers. Only minor clinical symptoms were seen and no febrile reactions occurred. With serologically primed individuals virus shedding was low, but a high proportion showed rises in serum antibody levels after vaccination and mean titres were high. With serologically unprimed volunteers shedding was high, about 75% yielding viruses but only at low titres and for a short duration. No revertant viruses were found and there was no evidence of transmission to potentially susceptible individuals housed in close contact to the vaccinees. Serum antibody responses with unprimed volunteers were, however, low. Only about one half showed increases in serum antibody titres after vaccination and mean titres were low. Nevertheless, challenge with live attenuated virus indicated a high degree of protection based on virological evidence of infection.

Antibody responses to vaccination with WRL 105 strain live influenza vaccine in previously vaccinated and unvaccinated volunteers

Intranasal vaccination with a single 0.5 ml dose of 10(7.0) EID 50 WRL 105 strain live influenza vaccine elicited four-fold or greater increases in circulating homotypic haemagglutinating inhibiting (HAI) antibody in 60 (64.5%) of 93 volunteers, or in 58 (74.4%) of 78 volunteers with HAI antibody titres before vaccination of less than or equal to 1/20. In comparison, in a group of volunteers vaccinated 9 months previously re-vaccination elicited antibody responses in only 4 (6.9%) of 58 volunteers, or in 3 (14.3%) of 21 volunteers with antibody titres before vaccination of less than or equal to 1/20. Titres of vaccine-induced antibody and antibody resulting from earlier natural infection appeared to fall slowly and at equivalent rates over a 9 month period.

A clinical trial with Alice/R-75 strain, live attenuated serum inhibitor-resistant intranasal bivalent influenza A/B vaccine

A clinical trial was conducted with Alice/R-75 strain live attenuated intranasal influenza A/B vaccine. With double blind control 88 adult volunteers were administered 2 doses of Alice/R-75 vaccine, 93 volunteers received one dose of Alice/R-75 vaccine and one dose placebo solution and 94 subjects were administered 2 doses of placebo solution. Twenty-three other subjects received Alice strain monovalent influenza A vaccine. For comparison, data from 21 subjects who received monovalent intranasal R-75 strain influenza B in two doses is included. The vaccine was generally well tolerated. Four-fold serum hemagglutination-inhibiting (HAI) antibody titer rises to A/England/42/72 occurred in 39% of the monovalent Alice strain vaccines; in contrast 18% of those given 2 doses of bivalent Alice/R-75 vaccine and 11% of those given 1 dose of bivalent vaccine had similar four-fold HAI antibody titer rises. HAI antibody titer rises to influenza B/Hong Kong/72 occurred in 38% of R-75 strain monovalent vaccinees, 14% of Alice/R-75 2-dose vaccinees and 11% of Alice/R-75 one dose vaccinees. An epidemic of influenza at onset of the study made evaluation of the efficacy of the vaccine impossible.

Immunity to attenuated influenza virus WRL 105 infection induced by heterologous, inactivated influenza A virus vaccines

Groups of student volunteers were immunized with one of five different inactivated influenza virus vaccines. The concentration of virus in the various vaccines differed by both the international unitage test and by the concentration of haemagglutinin, as measured by the single radial diffusion test; the results of the two methods of standardization showed no correlation. The serum HI response to immunization was variable; volunteers given A/England/72 showed a 16.6-fold increase in homologous serum antibody titre whilst volunteers given A/Hong Kong/68 vaccine showed a 4.2-fold increase. The variable response of volunteers to immunization could not be explained by the varied concentration of virus in the vaccines, as measured by either test, the titres of serum HI antibody present before immunization, or a combination of these two factors.The ability to infect volunteers with WRL 105 virus 4 weeks after immunization with heterologous, inactivated virus vaccine was directly related to the degree of cross-reactivity between the haemagglutinins of this vaccine virus and WRL 105 virus. Thus, the greatest number of infections by the challenge virus were seen in volunteers given A/Hong Kong/68 vaccine, less were observed in volunteers given A/England/72 vaccine, and least were found in groups given A/Port Chalmers/73 or A/Scotland/74 vaccine. However, compared with the incidence of infection in volunteers given B/Hong Kong/73 vaccine, all the heterologous influenza A vaccine gave some immunity to challenge infection.

Longer term effects of live influenza vaccine in patients with chronic pulmonary disease

WRL 105 strain live influenza vaccine or placebo was given to patients with chronic bronchitis in a double-blind study. The twenty-one vaccinated and twenty-three placebo-treated patients made daily self-assessments of the severity of symptoms of cough, breathlessness, tightness, wheeze, and sputum production in the following 20 weeks. Symptom scores in the first 2 weeks after vaccination or treatment with placebo were used to calculate a baseline range for each patient. Comparison of symptoms in the two groups in the baseline period showed that symptoms were more often reported by vaccinated than by placebo-treated patients but the differences were not statistically significant. One patient who responded serologically to vaccination had a moderately severe influenzal illness starting on the day after vaccination. Comparison of symptom scores during the 18-week surveillance period with baseline values showed that symptoms of breathlessness, tightness, wheeze and cough were significantly more common in vaccinated than in placebo-treated patients and that antibiotic usage was more common in the vaccinated group.

WRL 105 strain live attenuated influenza vaccine; comparison of one and two dose schedules

Haemagglutinating inhibiting antibody (HAI) responses were determined and clinical reactions recorded in 162 adult volunteers who received either 1 or 2 intranasal doses of 10(7-0) EID50 WRL 105 strain live influenza vaccine or placebo. After administration of a single dose of vaccine significant antibody responses were obtained in 69 (70%) of 98 volunteers with initial antibody titres of less than or equal to 1/20. Of the 70 volunteers who received a second dose of vaccine, 62 provided a further post-vaccination sample of serum, and only 3 (4-8%), who had not responded to the first dose of vaccine, produced a significant antibody response. Local, upper respiratory and constitutional symptoms were recorded more frequently after the administration of a first dose of vaccine than after placebo or a second dose of vaccine. The symptoms were of a minor nature except in one volunteer who, after the first dose of vaccine, developed influenzal symptoms followed by bronchitis.