Phase 3 study of smallpox vaccine meets study end points
Bavarian Nordic today announced promising findings for a phase 3 study of its smallpox vaccine Imvamune, which compared its efficacy against ACAM200, the smallpox vaccine currently licensed in the United States. Imvamune is a nonreplicating vaccine designed to be safer for use in patients who shouldn't be given the replicating vaccine, such as those with atopic dermatitis or HIV.
The open-label study of 440 volunteers at a US military facility in South Korea by a team from the United States Army Medical Research Institute of Infectious Diseases (USAMRIID) showed that peak neutralizing antibodies were twice as high as with ACAM2000, which met one of the two study end points and suggested the vaccine prompted a statistically superior immune response, according to a company news release. The study also looked at the vaccine's ability to prevent or attenuate a pustule, scab, or scar in people vaccinated with the second dose. The study found that primary vaccination with Imvamune reduced lesion size and prevented lesions in most subjects revaccinated with ACAM2000.
The study is the second phase 3 study to support a favorable safety profile and efficacy when compared with replicating smallpox vaccines, the company said, and paves the way for it to apply for licensing with the US Food and Drug Administration (FDA) in the last half of this year. If the vaccine is approved, Bavarian Nordic would be eligible for a priority review voucher that it could use to streamline the review of a future license application or transfer to another company.
Paul Chaplin, Bavarian Nordic's president and chief executive officer, said in the release, "This program has only been possible through the consistent and strong support of numerous U.S. Government agencies and demonstrates what can be achieved through a successful public-private partnership to protect the public from the deliberate release of the smallpox virus."
Col Gary Wheeler, commander of USAMRIID, said in a USAMRIID press release, "If approved, this vaccine will have a direct impact on improving force health protection for U.S. Soldiers and other service members who are required to be immunized against smallpox."
The company has already delivered 28 million of liquid-frozen Imvamune to the US Strategic National Stockpile for emergency use and has a contract to replenish the stockpile with a freeze-dried formation to extend the vaccine's shelf life.
Feb 8 Bavarian Nordic press release
Feb 8 USAMRIID press release
Incubation period for Salmonella cases often outside 'standard' range
Minnesota health officials report that, although the incubation period for Salmonella infection is often reported as ranging from 6 to 72 hours (3 days), 40% of culture-confirmed infections involved shorter or longer incubation periods, some as long as 16 days, according to their data published yesterday in Epidemiology & Infection.
The investigators combed through data on Minnesota salmonellosis outbreaks from 2000 through 2015, noting that 725 cases (out of 1,517) had enough data to calculate a precise incubation period—the time from exposure to first symptoms. Of those cases, 425 (59%) were culture-confirmed.
For all 725 cases, the time from exposure to onset of first symptom was 45 hours and to onset of an objective symptom was 49 hours. More than two-thirds (491, 68%) had incubation periods within the commonly referenced range of 6 to 72 hours, and 249 cases (34%) had incubation periods of 12 to 36 hours, which is often called the "usual" range.
The researchers determined that 65 cases (9%) had incubations less than 12 hours and 23 (3%) had incubations less than 6 hours. In addition, 211 cases (29%) had incubation periods longer than 72 hours, including 124 (17%) from 72 to 120 hours (5 days), 52 (7%) from 121 to 168 hours, and 35 (5%) longer than 168 hours (7 days)—most in the 8-to-9-day range but several in the 10-to-16-day range.
The authors also reported that culture-confirmed cases had significantly longer median periods to first symptom (54.5 vs. 29.8 hours) and to first objective symptom (62.5 vs. 35.5 hours) compared with the other cases. Of the culture-confirmed cases, only 60% involved incubation periods within the 6-to-72-hour range.
Feb 7 Epidemiol Infect abstract