This likely happened because COVID-19 precautions — such as social distancing, masks, and travel restrictions — sharply reduced social contact. With fewer opportunities to spread from person to person, B Yamagata couldn’t sustain transmission and eventually died out.
What I know about epidemiology would fit in the character limit here with a paragraph to spare, but that was my first thought on seeing this post.
What's really interesting is that it seems to have been very virulent in the winter of 2018, then in decline already before disappearing after 2020. I don't doubt Covid precautions killed it, but it may have already been in a vulnerable state.
Regulatory health agencies like the WHO, European Medicines Agency, and US CDC have recommended removing it from flu vaccines. This could allow room for other strains to be included in seasonal flu vaccines, improving overall vaccine effectiveness.
Good news is good news. I'll take it.
Thanks. Needed some good news today.
Great reporting. Thank you.