CDC has now released updated statistics for influenza A/H3N2 variant. This is an emerging strain of type A/H3N2, which is a triple-reassortant strain that includes genetic sequences from pandemic H1N1. Transmission has been predominantly swine-human, however there have been three instances of human-human transmission. It remains unclear whether this virus will supercede current globally circulating influenza A/H3N2.
Current case counts for A/H3N2 variant is 276, with 13 hospitalizations. The hospitalization rate is 4.7%. There have been no fatalities, however the case count is insufficient statistically to "draw out" this observation. We will need to see an estimate of more than 15,000 cases before we see our first fatality, if the pediatric fatality rate is approximate to that of pandemic H1N1 (i.e. 0.006%- see below).
Total cases (all ages): 61 milllion
Total hospitalizations (all ages): 274,000 (0.4%)
Total fatalities (all ages): 12,470 (0.02%)
Total pediatric cases: 20 million
Total pediatric hospitalizations (all ages): 87,000 (0.4%)
Total pediatric fatalities (all ages): 1,280 (0.006%)
Current hospitalization rate for A/H3N2 variant is more than 10
times that of pandemic H1N1 if considering all ages. But A/H3N2 variant
affects predominantly children. Therefore, the current pediatric hospitalization rate is 10 times that of pandemic H1N1. It should be emphasized the current case count for A/H3N2 variant is based on recognized cases and likely reflects a degree of underreporting.
Vigilance and submission of samples for testing is strongly recommended for the pediatric population this fall.