Study findings published today in The New England Journal of Medicine support the idea of using smaller doses of yellow fever vaccine to control outbreaks, researchers said.
In 2016, the world’s yellow fever vaccine stockpile was depleted during the response to two related outbreaks in Angola and the Democratic Republic of the Congo (DRC), which involved 7,334 suspected cases and up to 393 deaths, according to WHO. The shortage complicated the DRC government’s plan to prevent the spread of the virus by vaccinating 7.6 million people in the capital city of Kinshasa, Steve Ahuka-Mundeke, MD, PhD, from the National Institute of Biomedical Research in the DRC, and colleagues, including several from the CDC, wrote in the new study.
In response, and under the guidance of WHO, Ahuka-Mundeke and colleagues said the DRC government used a fractional dose of 0.1 mL — one-fifth the size of the normal dose — to stretch the vaccine supply. During the campaign, Ahuka-Mundeke and colleagues recruited participants from six vaccination sites in Kinshasa and tested their blood for neutralizing antibody tiers against yellow fever virus before vaccination and again 28 to 35 days after they were vaccinated.
Inhabitants of Rio de Janeiro state in Brazil line up for yellow fever vaccinations. Amid a yellow fever vaccine shortage in 2016, researchers in the Democratic Republic of the Congo found that using fractional vaccine doses was effective during an outbreak.
Among 716 participants included in the study, 98% were seropositive after vaccination, including 98% of the 493 participants who were seronegative at baseline, the researchers reported. Among 223 participants who were seropositive at baseline, 66% had an immune response.
“This rate of seroconversion suggests that the use of a fractional-dose vaccination is a viable approach for providing immunity and thus containing yellow fever outbreaks,” Ahuka-Mundeke and colleagues wrote. “This finding is important, given the ongoing risk of outbreaks of yellow fever globally, as shown in 2017 in Brazil, where more than 26 million vaccine doses of yellow fever vaccine were distributed to control an outbreak during the beginning of the year.” – by Gerard Gallagher
Ahuka-Mundeke S, et al. N Engl J Med. 2018;doi:10.1056/NEJMoa1710430.
Disclosures: The authors report no relevant financial disclosures.