News Scan for Jan 22, 2018

Flu priming and vaccine protection
1918 pandemic flu by income
Saudi MERS case
Yellow fever in Brazil
Meningococcal B vaccine

Study finds more evidence of impact of flu priming on vaccine protection

Adults born from 1958 to 1979 may have experienced a drop in protection against 2009 H1N1 during the 2015-16 flu season because of priming with other H1N1 viruses during their younger years, according to a group led by the US Centers for Disease Control and Prevention.

Using information from the Influenza Vaccine Effectiveness Network, the group, which included researchers from other universities and institutions, looked at effectiveness against lab-confirmed 2009 H1N1 by birth cohort from the five seasons after the 2009 H1N1 pandemic: the 2011-12 through 2015-16 seasons. The team reported its findings last week in the Journal of Infectious Diseases.

The birth cohorts were defined by likely priming by H1N1 viruses that circulated from 1918 to 2015. The study included 2,115 people who tested positive for 2009 H1N1 and 14,696 who tested negative.

Overall, vaccine effectiveness against 2009 H1N1 was 61% across the first four seasons they examined, but it dropped to 47% during the 2015-16 season. For those born from 1958 to 1979, however, effectiveness against the strain was 22% that season—much lower than the 61% seen in other birth cohorts.

The team noted that changes in the 2009 H1N1 virus that circulated during the 2015-16 season may have influenced antibody response in the cohort in that age range and that the replacement of the 2009 H1N1 vaccine strain to one that covers group 6B.1 should lead to better protection.
Jan 18 J Infect Dis abstract


Study shows 1918 pandemic flu waves hitting poor, wealthy differently

The first wave of the 1918-19 flu pandemic 100 years ago affected the poor the heaviest in Bergen, Norway, while the second wave hit the rich harder, according to a study yesterday in Influenza and Other Respiratory Viruses.

Epidemiologist Svenn-Erik Mamelund, PhD, of the Oslo and Akershus University College of Applied Sciences, analyzed data on 10,633 patients who had influenza-like illness (ILI)—and socioeconomic status (SES) —in the city during the three waves, including those before and after the "fall wave" of October to December 1918.

Mamelund found that higher SES was negatively associated with ILI in the first wave but positively associated with ILI in the fall wave. He also discovered that, at all SES levels, men had the highest ILI in the summer while women had the highest ILI in the fall. He found no SES or sex differences in ILI during the winter 1919 wave.

He concluded, "For the first time it is documented a crossover in the role of socioeconomic status in 1918 pandemic morbidity. The poor came down with influenza first, while the rich with less exposure in the first wave had the highest morbidity in the second wave. The study suggest that socioeconomically disadvantaged should be prioritized if vaccines are of limited availability in a future pandemic."
Jan 21 Influenza Other Respir Viruses abstract


One new MERS case reported in Saudi Arabia; WHO details December cases

The Saudi Arabian Ministry of Health (MOH) reported a new MERS case late last week.

The MOH said on Jan 19 that a 58-year-old Saudi man from Najran is in stable condition after being diagnosed as having MERS-CoV (Middle East respiratory syndrome coronavirus). The man's source of infection is listed as "primary," meaning it's unlikely he contracted the virus from another person.

The latest case raises Saudi Arabia's total since the virus was first detected in humans in 2012 to 1,777, which includes 724 deaths. Eight people are currently being treated for their infections.

In other MERS news, the World Health Organization (WHO) released its epidemiologic data on all MERS cases recorded in December of 2017. A total of six cases, four in Saudi Arabia and one each in Malaysia and the United Arab Emirates, were documented. None of the cases was healthcare related. The WHO said cumulative data from 2017 show no major epidemiologic differences from data collected during 2015 and 2016.

"The age group of those aged 50–59 years continues to be the group at highest risk for acquiring infection as primary cases. For secondary cases, it is the age group of 30–39 years who are mostly at risk," the WHO said. "The number of deaths is higher in the age group of 50–59 years for primary cases and 70–79 years for secondary cases."
Jan 19 MOH report
Jan 22 WHO report


WHO weighs in on Brazil's yellow fever outbreak

Confirmed yellow fever cases in Brazil have tripled over recent weeks, mainly in Sao Paulo and Minas Gerais states, the latter of which has declared a public health emergency over the outbreak.

The WHO said in an update today that from Jul 1, 2017, to Jan 14, 2018, 35 cases have been confirmed in Brazil, 20 of them fatal. Health officials are also investigating 145 suspected cases. Of the confirmed cases, 20 are from Sao Paulo, 11 are from Minas Gerais, 3 are from Rio de Janeiro, and 1 is from Federal district.

Of people infected in the latest illness uptick, all lived in areas were epizootics have been reported in monkeys. The cases in Minas Gerais are from cities that didn't report human cases during the earlier yellow fever outbreak in 2016 and 2017. The affected cities in Rio de Janeiro state are just 60 miles from the city of Rio de Janeiro, which is the country's most populated metropolitan area.

The number of epizootics significantly increased in September 2017, which the WHO says is a concern, because it shows a high level of virus circulations where ecosystems are favorable for transmission and are located near urban areas of large cities and locations that previously weren't thought to be at risk.

The WHO said Brazil's recently announced mass vaccination campaign is expected to limit transmission, but because of its size and scope will present a significant logistical challenge. The agency added that a recent illness in a traveler from the Netherlands shows the need for countries to reinforce their vaccination messaging to travelers. On Jan 16 the WHO updated its guidance, urging vaccination for those visiting any area in Sao Paulo state.

Minas Gerais state has declared a public health emergency over its yellow fever outbreak, the BBC reported yesterday. At least 15 deaths have been reported since December, with illnesses noted in several areas, including Belo Horizonte, the state's capital.
Jan 22 WHO statement
Jan 21 BBC report


Review finds meningococcal B vaccine safe, immunogenic

A meta-analysis of 18 clinical trials plus other data published in The Lancet Infectious Diseases found the meningococcal B vaccine (4CMenB) safe and immunogenic in children and adolescents, but with less-than-optimal immune response for two of the reference strains tested.

The researchers included in their analysis 10 randomized trials and 8 follow-up extension trials of 4CMenB (Bexsero, made by Novartis) that assessed immunogenicity against at least one of four Neisseria meningitidis serogroup B reference strains (44-76/SL, 5/99, NZ98/254, and M10713) and included children and adolescents who had received two or more vaccine doses. Bexsero is licensed in more than 35 countries and was approved for use in the United States in 2015.

The researchers discovered that, 30 days after the primary vaccine course, the vaccine induced seroconversion in 91% of patients, but the rate varied somewhat by strain: 92% for the 44/76-SL strain, 91% for the 5/99 strain, 84% for the NZ98-254 strain, and 87% for the M10713 strain. Six months after the primary course, immunogenicity remained adequate to high against all three tested strains (5/99, 44/76-SL, and NZ98/254) in adolescents (77% or higher), and against two of four strains (5/99 and 44/76-SL) tested in children (67% or higher). The rate of seroconversion substantially declined for M10713 (less than 50%) and NZ98/254 (less than 35%).

A booster dose re-enhanced the proportion of patients who achieved seroconversion to 93% or higher for all four strains, but immunogenicity remained high 6 months after the booster dose only for strains 5/99 (95%) and M10713 (75%). The proportion of patients who achieved seroconversion against strains 44/76-SL and NZ98/254, in contrast returned to levels akin to those recorded 6 months after the primary course.

The authors conclude, "With an acceptable short-term safety profile, high immunogenicity in children and adolescents within the first months after vaccination, and adequate-to-high persistence of immunogenicity (against all tested strains in adolescents and against three of four strains in children), 4CMenB might be a crucial tool to control meningococcal B disease.

"A booster dose is required for children to prolong the protection against strain M10713, and the long-term immunogenicity against strain NZ98/254 remains suboptimal. The clinical significance of the poor persistence against the NZ98/254 strain, and coverage against outbreak strains, require further study."
Jan 19 Lancet Infect Dis study

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