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Understanding Influenza B: The Lesser Known Virus

Unlike Influenza A, Influenza B does not have subtypes but is classified into distinct lineages, such as Yamagata and Victoria. It is known to cause localised outbreaks and can lead to a significant number of flu cases, albeit on a smaller scale compared to Influenza A. Regarding the ecology of the virus, Influenza B has a complex interaction with its natural hosts. Influenza B is primarily associated with human-to-human transmission and exhibits seasonal patterns of activity. In addition to humans, some evidence suggests that Influenza B viruses can infect seals and ferrets, although their significance in the overall ecology of the virus remains relatively limited compared to the human…

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 Natural History of Influenza B Virus—Current Knowledge on Treatment, Resistance and Therapeutic Options

Influenza B virus (IBV) significantly impacts the health and the economy of the global population. WHO global health estimates project 1 billion flu cases annually, with 3 to 5 million resulting in severe disease and 0.3 to 0.5 million influenza-related deaths worldwide. Influenza B virus epidemics result in significant economic losses due to healthcare expenses, reduced workforce productivity, and strain on healthcare systems. Influenza B virus epidemics, such as the 1987–1988 Yamagata lineage outbreak and the 2001–2002 Victoria lineage outbreak, had a significant global impact. IBV’s fast mutation and replication rates facilitate rapid adaptation to the environment, enabling the evasion of existing immunity and the development of resistance to virus-targeting treatments. This leads to annual outbreaks and necessitates the development of new vaccination formulations.

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A comprehensive review of influenza B virus, its biological and clinical aspects

Influenza B virus (IBV) stands as a paradox, often overshadowed by its more notorious counterpart, influenza A virus (IAV). Yet, it remains a captivating and elusive subject of scientific inquiry. Influenza B is important because it causes seasonal flu outbreaks that can lead to severe respiratory illnesses, including bronchitis, pneumonia, and exacerbations of chronic conditions like asthma.

Flu A vs Flu B: What’s the Difference and Does It Matter?

Flu A infects both humans and animals, including birds and pigs. Because it can move between species, it has more opportunities to change and adapt. This is why Flu A is responsible for major outbreaks and flu pandemics throughout history. Flu B, on the other hand, primarily affects humans. It changes more slowly and tends to cause seasonal outbreaks rather than global pandemics. While Flu B is often perceived as milder, it can still cause significant illness—especially in children.

Importance of Influenza B Virus

The Influenza B virus is an enveloped member of the Orthomyxoviridae family. Influenza B, along with Influenza A, is responsible for the respiratory illness influenza (flu). Influenza B differs from influenza A in that influenza B only infects humans and seals, while influenza A infects a wide range of animals, including birds and pigs. This increased host range allows influenza A to mutate about 2-3 times faster than influenza B. Influenza B is still able to mutate fast enough to prevent lasting immunity, making prevention and regular vaccination essential. Symptoms of influenza B match those of influenza A but tend to be a little less severe.

Influenza B infections in children: A review

Influenza B (IFB) virus belongs to the Orthomyxoviridae family and has two antigenically and genetically distinct lineages; B/Victoria/2/87-like (Victoria lineage) and B/Yamagata/16/88-like (Yamagata lineage). The illness caused by IFB differs from that caused by influenza A. Outbreaks of IFB occur worldwide and young children exposed to IFB are likely to have a higher disease severity compared with adults. IFB mostly causes mild to moderate respiratory illness in healthy children.

Influenza B is Dominating This Year's Flu Season—Here's What You Need to Know

A big difference between influenza B and influenza A is that influenza B typically comes after influenza A, hitting later in the season around springtime.

Influenza B is trying to escape our vaccine

The B viruses are less diverse and mutate more slowly, which makes them generally less dangerous. We also get to pick two B strains every year, since the majority of people in the U.S. get a quadrivalent vaccine (meaning it has four parts). Most years there are relatively minor changes to the B virus genome, and therefore small changes to the viruses contained in the vaccine.

Study finds influenza B may be more severe than thought

The findings challenge the notion that influenza B infections are milder than influenza A infections, the group reported. CDC data from 2004 to 2008 suggest 34% of 309 pediatric flu deaths were linked to influenza B, they noted, adding that many of the case-patients had no underlying risk factors for flu complications, other than that they were young.

The A, B, and C of influenza virus

Influenza B viruses cause the same spectrum of disease as influenza A. However, influenza B viruses do not cause pandemics. This property may be a consequence of the limited host range of the virus – humans and seals – which limits the generation of new strains by reassortment. The virus causes significant morbidity: in the US in 2008, approximately one-third of all laboratory confirmed cases of influenza were caused by influenza B. Consequently the seasonal trivalent influenza vaccine contains an influenza B virus component.

What's In A Flu Name? H's And N's Tell A Tale

Although influenza B can make you just as sick as A, it has never triggered a worldwide pandemic. Those have all come from the influenza A strains.

When “B” becomes “A”: the emerging threat of influenza B virus

Influenza B is the most prominent circulating strain of influenza every four to five years. Furthermore, influenza B infections carried higher risks of hospitalisations compared to influenza A infections in HIV patients [5]. Similarly, influenza B has been described to have significantly higher mortality rates compared to influenza A strains.