MEAD JOHNSON HAS SOLD OVER 3.5 MIL. DOSES OF HAEMOPHILUS INFLUENZAE B VACCINE DEVELOPED BY PRAXIS; PRELIMINARY EFFICACY DATA IN 95% RANGE
Mead Johnson has sold "over 3.5 mil. doses" of the Haemophilus influenzae B vaccine developed by Praxis Biologics since the product's introduction in early May, Praxis President David Smith, MD, told FDA's Vaccines and Related Biological Products Advisory Cmte. on Nov. 18. In his report of Praxis' preliminary post-marketing data during the public hearing portion of the meeting, Smith noted that from 3.5 to 3.8 mil. doses have been sold since the vaccine's market introduction. Based on the vaccine's current rate of sales, Mead Johnson's 1985 revenues from the product should easily top $30 mil. at the vaccine's current price of $6.50 to $7.00 per dose. The Haemophilus influenzae B vaccine was licensed by FDA on April 12 of this year. "Through market surveys, which were conducted the week ending Nov. 15 into 100 offices of pediatricians and 100 general practitioner offices, we are confident that more than 2.3 mil. doses have been administered to children, or roughly 66% of the dose ]sold[," Smith said. "We feel that this is a very conservative estimate." In presenting the preliminary efficacy data to the cmte., Smith calculated that the figures are based on "at least 7.3 mil. patient months." Smith reported that based on Centers for Disease Control (CDC) attack rate estimates for haemophilus influenzae B, the vaccine's efficacy rate in children 24-35 months and 36-47 months old was in the 96-97% range. Acknowledging that the preliminary data has been taken outside of the flu season, Smith pointed out that reducing the CDC-derived attack rate figure by 15% would still show an efficacy rate of just under 96%. Mead Johnson Has Received Less Than 100 Adverse Side Effect Reports From 2.3 Mil. Doses Administered -- Praxis Says Since the May introduction, Praxis had received reports of 16 Haemophilus influenzae B cases occurring in children that had been vaccinated, Smith said. He noted that the reports have come to Praxis via three different routes: through FDA; through CDC; and through Mead Johnson's sales force. "There have been 500 salesmen of the Mead Johnson company in the pediatrician offices making frequent visits, and this is clearly one of the questions that they have been challenged to ask in each one of their visits," Smith said. "We've also made some calls to each of the couple dozen major university hospitals that might be expected to see cases on referral." Smith acknowledged that there may be "some slippage" in terms of post-vaccine Haemophilus influenzae B cases missed. However, he said he was "convinced that ]the cases that turned up in the data[ represent by and large the vast majority." Explaining the reason for his informal presentation, Smith said he wanted to give the cmte. some indication that the vaccine was working "within the limits of the package insert." Asked to comment on the vaccine's adverse side effect profile so far, Smith said that "less than 100 adverse reactions" had been reported to Mead Johnson, with "approximately half" occurring more than 48 hours after vaccination. In addition, Smith noted that Praxis has followed 785 children since vaccination, and of that group, six had either a sore arm or a temperature of over 38 degrees C. The cmte. also heard a report on a recent CDC Advisory Cmte. on Immunization Practices meeting on polio vaccines from FDA Virology Dept. Director Gerald Quinan, MD, and received an update on the progress of FDA's work in the acellular pertussis vaccine area from FDA Div. of Bacterial Products Pertussis Branch Director Charles Manclark, PhD. Quinan reported that the CDC cmte. reviewed current policies on polio vaccine utilization, touching on issues such as the current status of polio in the U.S., comparative safety and immunogenicity of inactivated polio vaccine and oral polio vaccine, and intestinal immunity. Quinan noted that there has been one case of indigenous wild polio myelitis in the U.S. in the past four years. However, he noted that the current vaccine-related polio rate is estimated at one in 500,000 -- "a rate known to occur in oral polio vaccines, in general." Quinan cited two experimental inactivated polio vaccines under development, one developed by Connaught and the other by the Institute Merieux, which showed nearly 100% immunogenicity in clinicals without causing polio. Manclark noted that FDA's intramural pertussis program has narrowed down possible components of an acellular pertussis vaccine to three virulence factors from the disease -- lymphocytosis promoting factor, filamentous hemoglutin and agglutinogens. "There should be very little risk including them in vaccines," Manclark noted, since "only lymphocytosis promoting factor is toxic and methods are available to detoxify it." Manclark said that the three virulence factors "are the prime candidates ]for a first generation acellular vaccine[ and, in fact, have been included in vaccines that are being tested in the clinic today." The Swedish acellular pertussis vaccine trial, which is scheduled to begin in early 1986, will use two vaccines developed at the University of Osaka in Japan, Manclark said. He noted that one of the vaccines is a component vaccine made up of lymophocytosis promoting factor and filamentous hemoglutin in equal parts and the other vaccine "is a plain toxoid vaccine made up of lymphocytosis promoting factor, which is the toxoid."
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