News Scan for Dec 26, 2019

Global flu snapshot
;
High path H5N6 in Nigeria
;
Dengue vaccine screening
;
Non-medical vaccine exemptions

Flu continues to rise in several Northern Hemisphere countries

Flu levels continued to rise in North America, Europe, the Middle East, and parts of Asia, with some countries reporting higher than normal influenza B activity, the World Health Organization (WHO) said on Dec 20 in its latest global flu update.

In Canada, influenza B accounts for half of all flu detections, followed by 2009 H1N1. Europe is reporting mixed patterns, with many countries reporting mainly the H3N2 strain, but the eastern region and Portugal seeing dominant influenza B activity.

Influenza B circulation increased in central Asia.

Meanwhile, some countries in the Middle East reported rising flu levels, mainly from 2009 H1N1, but with a small proportion of influenza B viruses, as well.

China is starting to experience increased flu activity, with H3N2 most commonly detected. Illness levels are also on the rise in South Korea—mainly from 2009 H1N1—and Japan.

Globally, of samples tested from late November through the first part of December, 74.9% were influenza A, and of the subtyped influenza A viruses, 69.8% were H3N2.
Dec 20 WHO global flu update

 

Tests find high path H5N6 in earlier Nigerian poultry outbreak

Further testing of H5N6 avian influenza samples from birds infected in a June outbreak in Nigeria found that the virus was highly pathogenic, rather than low pathogenic, as originally reported. The event, first reported in November, marked the first H5N6 detection in Africa.

In a Dec 23 updated notification, the World Organization for Animal Health (OIE) said intravenous pathogenicity index lab analysis confirmed the H5N6 samples as highly pathogenic. The virus was found during active surveillance at a market in Sokoto province in the northwest of the country, where it sickened 150 of 2,449 birds.
Dec 23 OIE report on H5N6 in Nigeria
Dec 2 CIDRAP News scan "H5N6 avian flu reported for first time in Africa"

 

Study finds screen-and-vaccinate dengue policy cost effective

A screen-and-vaccinate policy related to tetravalent dengue immunization is likely to be cost-effective in most transmission settings, researchers reported in the Dec 23 edition of Vaccine.

The dengue vaccine, which is relatively new and has been adopted by some countries, carries a risk of severe dengue illness and hospitalization in those who were seronegative before receiving it. As such, the WHO recommends a screen-and-vaccinate policy, but questions persist about the public health impact and cost effectiveness of the step.

For the study, a research team from Sanofi, the vaccine's maker, and Brandeis University used a previously reported transmission model based on results from three dengue vaccine efficacy trials. They also used data from an assessment of three dengue rapid tests, which all had high specificity and with sensitivities that ranged from 50% to 90%. The team analyzed the impact of the screen-and-vaccinate strategy in nine transmission settings, and examined the cost-effectiveness in 10 endemic countries.

When compared to a no-screening approach, the team found that the screen-and-vaccinate strategy was more effective in reducing the numbers of severe illnesses and hospitalizations and was cost-effective in all settings, except for areas of very low dengue transmission. They also found that the overall population impact was likely to be higher with several rounds of screening, with an up to 48% reduction in dengue hospitalization over 10 years with 5 rounds.
Dec 23 Vaccine abstract

In other dengue developments, two more local dengue cases have been reported in Florida's Miami Dade County, according to a Dec 23 Florida Department of Health update. The new illnesses bring the county's number of local cases for the year to 14.
Dec 23 Florida Health statement

 

Study: Barring non-medical exemptions increases vaccination rates

A study published earlier this week in PLOS Medicine showed a 2016 ban on non-medical vaccine exemptions in California increased vaccine uptake.

This is the first official study of the effects of the California law, and was conducted by researchers at the University of California-San Francisco. Researchers used county surveillance data to estimate how many children would have received the measles, mumps, rubella (MMR) vaccine if the law had not been enacted, and then compared that number to the number of children who received the vaccine. 

MMR coverage across the state increased 3.3 % after the law was passed, and nonmedical exemptions decreased by 2.4 %. Medical exemptions increased 0.4 %. On a county level, vaccine uptake varied greatly, ranging from a 6% decrease to a 26% increase.

"The largest increases in vaccine coverage were observed in the most 'high-risk' counties, meaning those with the lowest prepolicy vaccine coverage. Our findings suggest that government policies removing nonmedical exemptions can be effective at increasing vaccination coverage," the authors concluded.
Dec 23 PLOS Med study

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