False: Flu vaccine is only 10% effective this season

First of all, where did this information come from? This came from the vaccine effectiveness estimate from Australia (http://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2017.22.43.17-00707 ). More specifically, the 10% effectiveness was only for one strain, the A(H3). The estimates for the other strains were higher at 50% for strain A(H1) and 57% for strain B. The overall vaccine effectiveness was reported to be 33%. These data are out already as the flu season in Australia is during their cold season in May to September.

Given where this data came from, can this be applied to the US? On one hand, yes, because the composition of the flu vaccine in Australia is similar to that of the flu vaccine in the US.  Each flu season, the WHO gives recommendation on the composition of the flu vaccine for the northern hemisphere and another for the southern hemisphere (http://www.who.int/influenza/vaccines/virus/recommendations/en/). However, in Australia, flu vaccination is recommended only for the elderly, pregnant and chronically ill (http://www.immunise.health.gov.au/internet/immunise/publishing.nsf/Content/ATAGI-advice-influenza-vaccines-providers). Contrast this to the CDC recommendation for the US, which is everyone 6 months and older, excluding only those with medical contraindications. This difference is important to consider because the elderly and the chronically ill are known to not respond as well to vaccines compared to other members of the population. Therefore, despite receiving vaccination, this group has increased risk of not developing immunity, as if they did not receive any vaccine at all.

Historically, vaccine effectiveness in the US has ranged from 10%-60% beginning 2004-2005 season to 2016-2017 season (https://www.cdc.gov/flu/professionals/vaccination/effectiveness-studies.htm). Do we have the number yet for this season? No, because the flu season has not ended yet and therefore all the numbers that are given out are just estimate and are subject to change. Even if turns out to be 10% at the end of the season, does that mean we shouldn’t have used the vaccine? No, because if people are going to get sick, you want all the protection you can get from complications and death (one example: http://pediatrics.aappublications.org/content/early/2017/03/30/peds.2016-4244?sso=1&sso_redirect_count=1&nfstatus=401&nftoken=00000000-0000-0000-0000-000000000000&nfstatusdescription=ERROR%3a+No+local+token). We know flu kills. Car accident kills. Would you want to be in an accident without a seat belt?

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