Experts consider 4-strain influenza vaccine to fight B viruses

Selecting influenza strains to put in the flu vaccine each year is always difficult, given the ability of influenza viruses to change, but choosing the influenza B strain has become particularly vexing in recent years.  For a number of years, two distinct lineages of influenza B-Victoria and Yamagata-have been circulating and experts have found it almost impossible to predict which one would dominate in any winter.

Influenza Vaccine Composition 2009-10 Northern Hemisphere Winter

The formulation of influenza vaccines is reviewed twice yearly by the World Health Organization (WHO).  The WHO recently recommended that composition of influenza virus vaccines for use in the 2009-2010 northern hemisphere influenza season should contain the following three virus strains(1):

• A(H1N1): an A/Brisbane/59/2007 (H1N1) - like strain
• A(H3N2): an A/Brisbane/10/2007 (H3N2) - like strain,
• B: a B/Brisbane/60/2008- like strain,

Note that:
This formulation differs from that for the 2009 Southern Hemisphere vaccine only with respect to the type B component.
The predominance of Brisbane strains in recent WHO recommended formulations is a reflection of the efficient collection of suitable virus samples for vaccine development and not of excessive influenza activity in that area.

Reference
(1) http://www.who.int/csr/disease/influenza/200902_recommendation.pdf

World-first clinical trial shows mask-wearing significantly boosts flu protection

In a world-first clinical trial showing effectiveness of masks, researchers found adult wearers in the home were four times more likely than non-wearers to be protected against respiratory viruses, if they wore the mask.

Australia's Therapeutic Goods Administration (TGA), has approved the registration of a pandemic influenza (swine flu) vaccine, for use in adults and children aged 10 years and over. The vaccine is manufactured using the same process as that used to manufacture seasonal influenza vaccines.

The Australian Influenza Vaccine Committee (AIVC) met on 2 October 2009, and agreed to adopt the WHO recommendations announced in September for the 2010 influenza season southern hemisphere winter.

See details here 

December 2008

A US CDC-funded study by researchers at Duke Children's Hospital, found that vaccinating new mothers and other family members against influenza before their newborns leave the hospital creates a "cocooning effect" that may shelter unprotected children from the flu. The hospital-based outreach tested in this study proved effective at boosting immunization rates in parents - especially new fathers - and siblings who otherwise may not be vaccinated. Vaccinating newborns for flu is not recommended because they're too young, however they are a part of the population that is at highest risk. Newborns have the highest rate of hospitalizations due to influenza when compared to any other age group of children. In some seasons the influenza-associated mortality rate is highest among infants. The study showed that offering the flu vaccine to new mothers during their baby's stay in the hospital is an effective way to assure that all women have the opportunity to get vaccinated and thereby protect their own health and the health of their baby. It also proved to be a convenient, and possibly the most effective way for fathers to be vaccinated.

Content Updated (Tuesday, 6th January 2009)

During December 2009 and January 2010, the ISG conducted a survey amongst healthcare workers, seeking feedback on their response and attitudes to the pandemic flu vaccination.

December 2008

Influenza outbreaks in nursing homes are not reported to health authorities in 9 out of 10 cases, and low vaccination rates among staff are fuelling their spread. Influenza is potentially fatal to elderly people, but a three-year study by Australian experts has found that while only 2 per cent of nursing homes each year report having a flu outbreak, the real figure is over 20 per cent. Although over 90 per cent of residents were immunised, the researchers say the vaccine's slightly lower efficacy in older age groups means it is still possible for the infection to spread through nursing homes once it finds a way inside. Lead researcher Robert Booy, head of clinical research at the National Centre for Immunisation Research and Surveillance, told a recent conference in Sydney that the "reason flu gets brought in is because staff have relatively low rates of vaccination - perhaps 20 per cent of staff are vaccinated, and you need at least a 50 per cent uptake among staff to protect residents".

Content Updated (Tuesday, 6th January 2009)

November 2008

A study (Pediatrics. 2008 Nov;122(5):911-9) showed that even in an influenza season where there is not an optimal match between circulating strains of influenza and the strains contained in the influenza vaccine, the vaccine is likely to significantly protect young children, ages 6 to 59 months, against influenza. There was a 57-percent reduction in influenza-related medical visits in the children who received all recommended doses of the influenza vaccine compared to unvaccinated children in one of the two influenza seasons studied (2004-2005). Children 6 months up to 9 years of age need to have two vaccine doses if they are getting a flu vaccine for the first time. The study found no protection against flu for children who needed two vaccine doses and only received one.  

Content Updated (Tuesday, 6th January 2009)

November 2008

A study from Utrecht, Netherlands (Plos Medicine, 2008;5(10):1453-1460) noted that while annual influenza vaccination of health care workers (HCWs) is advised in most Western countries, adherence to this recommendation is generally low. Although protective effects of this intervention for nursing home patients have been demonstrated in some clinical trials, the exact relationship between increased vaccine uptake among HCWs and protection of patients remains unknown owing to variations between study designs, settings, intensity of influenza seasons, and failure to control all effect modifiers. Using a mathematical model to estimate the effects of HCW vaccination in different scenarios and to identify a herd immunity threshold in a nursing home department, the researchers used a stochastic individual-based model with discrete time intervals to simulate influenza virus transmission in a 30-bed long-term care nursing home department. The model revealed a robust linear relationship between the number of HCWs vaccinated and the expected number of influenza virus infections among patients. In a realistic scenario, approximately 60% of influenza virus infections among patients can be prevented when the HCW vaccination rate increases from 0 to 100% vaccination. A threshold for herd immunity was not detected.

Content Updated (Tuesday, 6th January 2009)