Fractional doses of yellow fever vaccine offer protection for up to 8 years
A study published in Vaccine shows that even small doses of the yellow fever vaccine are likely to offer protection against the virus for up to 8 years after vaccination. The information reassures countries like Brazil, who have used fractional dosing in an effort to stretch supplies of the vaccine during recent outbreaks.
The study was a follow-up to a 2009 Brazilian study comparing the serostatus of vaccine recipients given the full dose of the yellow fever vaccine (27,476 IU) compared to tapered doses (10,447 IU, 3,013 IU, 587 IU, 158 IU, and 31 IU). In that study, seropositivity was maintained for 10 months in all groups, except the group that received 31 IU.
Eight years later, researchers found 85% of 318 participants had antibodies against yellow fever, even in the 587 IU and 158 IU vaccination groups. The groups who had higher doses were more likely to be protected. All participants were male military members and confirmed they had not been revaccinated against yellow fever during the follow-up period.
The findings support the use of the yellow fever vaccine in fractional doses during outbreaks, but each fractional dose should have at least 587 IU. Current recommendations for the yellow fever vaccine from the World Health Organization are at least one dose of 1,000 IU every 10 years.
Though the yellow fever vaccine is one of the oldest, and most effective, vaccines in use, the world is suffering a shortage after outbreaks in the Democratic Republic of the Congo and Angola depleted stockpiles in 2016. In 2017, Brazil announced the use of factional doses in efforts to squelch a growing outbreak in that country.t
In a comment on the study on ProMED Mail, moderator Tom Yuill, PhD, with the University of Wisconsin, Madison, said, "This information will be extremely valuable for decision-making in the face of another yellow fever outbreak. The virus is not going to disappear in Africa nor in South America." ProMed Mail is the online reporting system of the International Society for Infectious Diseases.
Jun 27 Vaccine study
Jul 4 ProMed Mail post
More suspected cases tested as the DRC's Ebola countdown continues
Surveillance activities in the Democratic Republic of Congo (DRC) continue to identify and test new suspected Ebola cases, but no more confirmed cases have been reported over the past few days as the country edges closer to declaring the outbreak over.
In a Jul 3 situation report, the World Health Organization (WHO) said since Jun 26, 13 more suspected cases were identified, 10 from Bikoro, 2 from Iboko, and 1 from Wangata Health Zone in the provincial capital city of Mbandaka. Two rounds of testing have ruled out the disease in 11 of the patients, and second-round test results are still pending for two other people who tested negative in their initial tests.
The total number of cases is 53, which includes 38 confirmed, 15 probable, and 2 suspected cases. The number of deaths remains at 28.
Though the outbreak is largely contained, there is still a risk of flare-ups due to undetected transmission chains and the risk of sexual transmission by some male survivors, the WHO said.
Strengthened surveillance is in place, along with a survivor monitoring program, according to the WHO, which added that the revised risk has been downgraded to moderate for the DRC and low for the regional and global levels.
Jul 3 WHO situation update
CDC: Needle stick accident led to Brucella exposure
Today’s Morbidity and Mortality Weekly Report from the Centers for Disease Control and Prevention (CDC) contains a note about a veterinarian in Oregon diagnosed as having brucellosis after an accidental needle stick with the Brucellla abortus strain RB51 vaccine.
The patient administered the vaccine, intended for cattle, 3 weeks before suffering symptoms, including cough, malaise, myalgia, and fever. The patient was initially diagnosed as having pneumonia in the hospital and given doxycycline. After worsening symptoms, the patient was hospitalized and began oral rifampin and intravenous ceftriaxone and azithromycin, and continued oral doxycycline treatments before a brucellosis diagnosis was confirmed.
"This report serves as a reminder that occupational RB51 exposure is a risk among veterinary personnel. Clinicians, laboratory staff members, and public health officials should be aware of RB51 diagnosis and treatment challenges and be prepared to manage RB51 cases and exposure," the report said.
Brucellosis is uncommon in humans, and has been previously linked to veterinary needle sticks and raw milk consumption. The illness requires a positive culture to diagnose.
Jul 5 MMWR report