Influenza cases on the west coast of the United States are rising months earlier than normal. Public health experts are now stressing the importance of annual vaccinations.
Flu activity typically increases in December and peaks in February. This season has started earlier than usual, with higher numbers of positive cases recorded across several states.
Experts link the early start to a new mutation of the influenza A strain H1N1. This specific strain caused the 2009 swine flu pandemic.
The Centers for Disease Control and Prevention received reports from public health laboratories showing that this strain accounts for 242 out of 300 total influenza viruses recorded so far.
State data from California shows that influenza test positivity reached 9.65% by 10 October. During the previous two flu seasons, that rate hovered slightly above 1% during early October.
Utah recorded 242 influenza A cases by 11 October, according to Germ Watch, an Intermountain Health database. Last year, the state recorded only 10 cases during the same period. Parts of central Oregon have also experienced an influenza A surge.
The American Medical Association states that flu vaccines can reduce severe illness and hospitalisation. The organisation recommends flu shots for everyone aged six months and older.
The Food and Drug Administration approved the current flu vaccines in August. These formulations target H1N1, H3N2, which was the dominant strain last season, and one influenza B virus.
Scott Hensley, a microbiologist at the University of Pennsylvania, said two of the three components of this year’s vaccine appear to be very well matched to circulating flu strains.
Hensley said via email that the H1N1 mutation might affect antibodies in younger people, advising that it is probably a good idea to get vaccinated early.
Promotion of flu shots has been reduced under US health secretary Robert F Kennedy Jr. He is a longtime anti-vaccine activist who has engineered an overhaul of long-standing childhood vaccine schedules.
