Minor variants of influenza virus often fly under the radar, being transmitted right along with more predominant strains but remaining active as vaccines are not typically engineered to target them. However, new research from Nature Genetics suggests these overlooked strains carry a bigger viral punch than previously realized.
Influenza A has a high level of genetic diversity, but much of what is understood about the virus is based on the dominant strain. The diversity of minor strains, which aren't targeted by vaccines, and how they are transmitted between people, is less well-understood.
Researchers performed genomic sequencing on nasal cavity swabs from confirmed Hong Kong flu cases from 2009. They found most samples carried predominant strains of two types of virus, but all samples also carried minor strains and variants of the major strains. The researchers were surprised by how readily the variants were transmitted across individuals with the flu virus.
"We were able to look at the variants and could link individuals based on these variants," Elodie Ghedin, PhD, New York University professor and study co-author, said in a statement. "What stood out was also how these mixes of major and minor strains were being transmitted across the population during the 2009 pandemic — to the point where minor strains became dominant."