Those who are considering getting an influenza vaccine may now save on costs as the World Health Organization (WHO) and influenza experts have agreed that the ‘B/Yamagata lineage virus’ may no longer be necessary to be included in the flu shot.
This opens doors for the return of the trivalent influenza vaccine, which could be less expensive, and have more takers.
Why is the B/Yamagata lineage virus being excluded?
The vaccine is manufactured with a live virus, which is then inactivated or attenuated. However, the B/Yamagata lineage virus has not been seen for the past four years, according to experts.
“The virus is currently only found in the vaccine labs around globe, and any lapses in handling and containment, could bring it back into circulation,” Professor Parvaiz A. Koul, who is former director of Sher-e-Kashmir Institute of Medical Sciences, J&K, told The Wire.
An avid influenza researcher, Koul, further said, “It defies logic as to why you should vaccinate for an infection that has not been seen for the past four years.”
He strongly advocated for the reintroduction and re-adoption of trivalent flu shots.
Separately, the WHO, in a four-day consultative meeting on Composition of Influenza Virus Vaccines, on 23 February, decided to omit the B/Yamagata lineage virus from the vaccines.
In September, WHO had declared the need to exclude the B/Yamagata strain from the vaccine because it is no longer warranted. Its influenza vaccine composition advisory committee said, “[The] inclusion of a B/Yamagata lineage antigen in quadrivalent influenza vaccines is no longer warranted, and every effort should be made to exclude this component as soon as possible.”
Influenza vaccines are updated biannually so that they align with circulating strains to match evolving flu viruses. This process ensures effective protection from the virus.
The Yamagata lineage virus
Influenza B/Yamagata is one of the two main lineages of Influenza B viruses that commonly circulate and cause illness in humans, alongside Influenza B/Victoria. Influenza A and Influenza B are two types of viruses that cause the flu. Influenza A, in comparison to Influenza B, is usually responsible for more severe flu outbreaks due to its ability to undergo significant changes, called antigenic shift.
The fresh recommendations mandate the the egg-based flu vaccines must contain an A/Victoria/4897/2022 (H1N1)pdm09-like virus, an A/Thailand/8/2022 (H3N2)-like virus, and a B/Austria/1359417/2021 (B/Victoria lineage)-like virus. Similarly, the cell culture or recombinant-based flu vaccines may contain an A/Wisconsin/67/2022 (H1N1)pdm09-like virus, an A/Massachusetts/18/2022 (H3N2)-like virus, and a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.
These names represent specific strains of flu viruses. The first part refers to the type of flu virus (either influenza A or B), followed by the location where the virus was isolated (such as Victoria, Thailand, or Austria), and then a number and year indicating when the virus was identified or isolated. The egg-based flu vaccines are manufactured by growing the vaccine inside chicken eggs, while cell-culture based ones are grown inside animal eggs.
Days before WHO’s consultative meetings, the Lung India, a peer-reviewed medical journal, published a paper titled ‘Influenza vaccination: A case for removal of B/Yamagata from the quadrivalent vaccine’. The paper was written by professor Parvaiz A. Koul. The article advocated for the B Yamagata virus to be dropped from the vaccines.
It read: “After the onset of the COVID-19 pandemic, there was a virtual elimination of the influenza circulation from the globe (Influenza virus detections reported to FluNet for all viruses), which, however, reappeared in 2021 (mid-year). However, the recent global influenza surveillance has been notable in the virtual absence of the circulation of B/Yamagata lineage.”
“Given the virtual absence of B/Yamagata from the global circulation, after the onset of the COVID-19 pandemic in 2020, it would be apt to drop B/Yamagata totally from the vaccine and recommend only the trivalent vaccine with B/Victoria lineage,” it added.
“The two Influenza A lineages are determined by WHO twice every year, based on circulating strains data,” Koul said.
Kim Sampson, executive director – Asia Pacific Alliance for the Control of Influenza (APACI), and advisor to the Australian Immunisation Coalition, while endorsing the case for exclusion of B/Yamagata, told The Wire that the case was ‘clear’. “Inclusion of a non-existent virus in a vaccine is unreasonable, to say the least,” he said.
He further said, “The Lung India recommendations are very succinct and put forward a case for the removal of B/Yamagata from the forthcoming vaccine composition. Soon after the Lung India article publication, the WHO reached the same conclusion,” he said.
Koul’s article in Lung India said, “This (exclusion of B Yamagata) would also prevent inadvertent reintroduction of the vaccine-contained B/Yamagata strain into the community circulation.”
“Last year, WHO and the UK’s Medicines and Healthcare products Regulatory Agency noted in a meeting in London that there was no global circulation of B/Yamagata viruses since 2020, except for those derived from live attenuated vaccines,” he said in his article.
On February 28, the New England Journal of Medicine (NEJM) published a paper titled ‘Ending B Yamagata Flu Transmission – Shifting from Quadrivalent Vaccines’. The paper suggested that discussions may lead to an immediate return to trivalent vaccine formulation, analysing advisory group recommendations, manufacturer practices, regulatory requirements, and virus circulation patterns.
Earlier last week, the US Food and Drug Administration (FDA) issued a statement that called for the revamping of influenza vaccines, and switching to trivalent ones.
“In the interest of public health, FDA strongly recommended to influenza vaccine manufacturers the removal of the B/Yamagata lineage virus from seasonal influenza vaccines in the US for the 2024-2025 influenza season. FDA and the manufacturers have been working together so that the move from quadrivalent to trivalent seasonal influenza vaccines occurs for the upcoming influenza season,” read the statement.
The seasonal flu is a bi-annual incidence in India. As per estimates, ‘between 2,91,000 and 6,46,000 people die each year from seasonal influenza-associated respiratory illnesses, of which 36% occur in low and middle income countries (LMICs) like India’.
According to the WHO, children aged between six months and five years, pregnant women, adults aged 65 years and above, people with chronic medical conditions and healthcare workers constitute the high risk group for influenza.
Despite this, the vaccination coverage in India is ‘poor’.
A 2022 study assessing the vaccination coverage in older adults in India found that a miniscule 0.6% had taken the flu shot. Among healthcare workers, a study found that over 71% had been vaccinated at least once. The wide disparity, Koul said, could be due to a variety of reasons. “Many hospitals have influenza vaccines at subsidised prices for healthcare workers; healthcare workers have a better education about influenza and vaccines; the threat perception is more,” he said.
The cost
In India, the annual influenza vaccine shot costs around Rs 1,500 to Rs 2,000. Many believe that the switch to trivalent would reduce the cost and increase the uptake, especially in countries like India where the vaccine is not covered under any support or insurance system.
Sampson said having a lower price will certainly make people consider an annual flu shot, especially those in the community that have been introduced to the significance of vaccination against influenza. He said that while there certainly was ‘a correlation between price and uptake, it is not the only factor to be considered when thinking about influenza vaccination at a global level’.
“Government funded programmes will have the most significant impact, but such programmes are limited to countries that can afford them,” he said.
Koul said influenza vaccines saved lives. “Influenza is a serious threat for many people and has been responsible for so many deaths. These deaths are preventable,” he said. “Switching to trivalent flu shots could help bring the costs down and probably help in making vaccines more affordable for people,” he said.
CSL Seqirus, one of the largest vaccine companies, has announced that the transition from quadrivalent to trivalent influenza vaccines for the US will take place in time for the 2024-25 season. “For other countries, we are continuing to consult on the most optimal timing,” the company said.
