News Scan for Oct 15, 2013

News brief

Early start to measles vaccine regimen safer for kids

Children's first measles-containing vaccine dose should be given by 15 months of age because of an increased risk of fever and seizures when given later in their second year, according to findings of a retrospective, cohort study published yesterday in JAMA Pediatrics.

The authors, many from Kaiser Permanente, found that the relative risk of fever and seizures 7 to 10 days after administration of measles-containing vaccine, the time when vaccine virus replication is at its peak, was significantly greater among children 16 to 23 months of age at first dose than among those 12 to 15 months old, with the incidence of fever declining steadily from the early to the late part of that spectrum.

In evaluating the effects of different combinations of vaccines, the authors found that the risk of febrile seizures 7 to 10 days after administration of vaccine containing measles, mumps, rubella, and varicella (MMRV) was double than when MMR vaccine was given separately, with or without a separate varicella vaccine injection.

Even when measles-containing vaccine is given later than age 15 months, the risk of febrile seizures is small. Said senior author Nicola Klein, MD, PhD, in a press release from Kaiser Permanente, "Concerned parents should understand that the risk for febrile seizures after any measles-containing vaccine is low—less than one febrile seizure per 1,000 injections."

The researchers used data from the Vaccine Safety Datalink, a collaborative effort of the Centers for Disease Control and Prevention and nine managed care organizations, collected from 2001 to 2011. A total of 840,348 children were included.
Oct 14 JAMA Pediatr abstract

Phase 3 dengue vaccine trial shows good safety, immune response

Three doses of a four-strain dengue candidate vaccine were safe and immunogenic in children in a phase 3 trial whose results were detailed yesterday in Vaccine.

An international team enrolled 250 Malaysian children aged 2 to 11 years in the study of Sanofi Pasteur's CYD-TDV vaccine. The children were randomized 4:1 to receive CYD-TDV or placebo at 0, 6, and 12 months.

Adverse events were similar between the groups after each dose, and serious adverse events were actually higher in the placebo group (11.8% vs 5.5%).

Geometric mean titers (GMTs) of antibodies increased after two vaccine doses for all four dengue virus (DENV) strains in the vaccine compared with baseline, ranging from 4.8-fold for DENV-1 to 8.1-fold for DENV-3. GMTs further increased after the third vaccine dose for DENV-1 and DENV-2, and increases from baseline after three doses ranged from 6.1-fold (DENV-1) to 8.0-fold (DENV-3).
Oct 14 Vaccine study

Flu Scan for Oct 15, 2013

News brief

H5N1 outbreaks strike two Vietnamese provinces

Vietnam's agriculture ministry yesterday reported an H5N1 avian influenza outbreak in ducks in chickens at village in Hoa Binh province, according to a report from the World Organization for Animal Health (OIE). The virus killed 370 of 1,175 susceptible birds, and the remaining 805 birds were destroyed to control the spread of the virus.

Investigators haven't pinned down the source of the virus, the report said. Hoa Binh is a mountainous province located in the country's Northwest region. The outbreak is Vietnam's first since late July.

In other developments, the Vietnamese news media reported another H5N1 outbreak in poultry, located at a farm in Bac Lieu province, according to an Oct 13 Reuters story. Authorities culled 3,460 chickens to curb the spread of the virus.

The outbreak was first reported by Thanh Nien, a newspaper based in Ho Chi Minh City. Bac Lieu province is located on the southern tip of Vietnam in the Mekong Delta region.
Oct 14 OIE report
Oct 13 Reuters story

FDA study: Kids get far less mercury from flu vaccines than from food

The mercury to which some children are exposed from influenza vaccines is far less than what they are exposed to from food, according to a new study from scientists with the US Food and Drug Administration (FDA).

The use of thimerosal, a mercury compound, as a preservative in childhood vaccines has been largely eliminated over the past decade through the use of single-dose vaccine vials. But some flu vaccines are still distributed in multidose vials containing thimerosal, the authors note in their report in Risk Analysis.

They write that thimerosal is metabolized to ethylmercury, while mercury occurs in food as methylmercury. Since 2001, pharmacokinetic studies have indicated that ethylmercury is cleared from the bodies of both infants and adults much faster than methylmercury is.

The authors estimated the body burden of mercury in children by using data from experiments in which infant monkeys were episodically exposed to thimerosal or methylmercury at identical doses.

They calculated that the mercury burden due to yearly exposures to thimerosal in the first 4.5 years of life is more than 100 times lower than the US Environmental Protection Agency regulatory limit for dietary methylmercury. Also, peak thimerosal-related mercury levels in the body are always below the limit for methylmercury over the same period, they found.

"Together with the robust human epidemiological data for thimerosal, our results, which are based on a 'worst-case' comparison, support the continued safety of this preservative at levels currently used in multidose inactivated influenza vaccines in the United States," the authors conclude.
Oct 10 Risk Analysis abstract

H7N9 vaccine trial to start shortly

Two schedules of H7N9 nasal vaccine and boosters will be tested on 48 volunteers at the University of Rochester Medical Center (URMC), Rochester, N.Y., later this fall. The research is funded by the National Institutes of Health, according to a URMC news release yesterday.

Subjects will be assigned to one of two groups. One group will receive an intranasal vaccine containing a live, weakened form of H7N9 virus, followed by a 12-day isolation period and then a booster shot of inactivated H7N9 in an outpatient clinic setting. The other group will receive two doses of the same intranasal vaccine 28 days apart, with each followed by 12 days of isolation, and then a booster.

The subjects' antibody responses will be measured to determine which regimen is preferable—information that could help shape recommendations for a potential H7N9 pandemic.

Subjects will receive compensation for their participation. They have to be 18 to 49 years of age, in good health, not allergic to eggs, and not pregnant or asthmatic. The experimental vaccines are made by MedImmune and Sanofi.
Oct 14 URMC news release
Application form for participants