As ususal, posting data well behind the actual date. This is through March 1.
- Two thousand four hundred one (27.2%) specimens tested by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories were positive for influenza.
- The proportion of deaths attributed to pneumonia and influenza was above the epidemic threshold for the eighth consecutive week.
- The proportion of outpatient visits for influenza-like illness (ILI) and acute respiratory illness (ARI) was above national baseline levels. ILI decreased in seven of the nine regions compared to week 8, but remained above region-specific baselines in all nine regions. The Mid-Atlantic and West North Central regions reported ARI at or above their region specific baselines.
- Forty-seven states reported widespread influenza activity; three states reported regional influenza activity; and the District of Columbia reported local influenza activity.
Neuraminidase Inhibitor Antiviral Drugs: Of the 743 influenza A and B viruses from the United States tested for antiviral resistance so far this season, 45 (6.1%) have been found to be resistant to oseltamivir. Currently all of the resistant viruses are H1N1 viruses, with 45 (8.7%) of 519 H1N1 viruses tested exhibiting a genetic mutation that confers oseltamivir resistance. All tested viruses retain their sensitivity to zanamivir.
Adamantane Antiviral Drugs: Resistance to the adamantanes continues to be high. Among 511 influenza A viruses tested, 111 (21.7%) are resistant to adamantanes, including 98.9% of H3N2 viruses and 4.3% of H1N1 viruses. The adamantanes are not effective against influenza B viruses.
Based on the level of oseltamivir resistance observed in only one influenza subtype, H1N1, and persisting high levels of resistance to the adamantanes in both H3N2 and H1N1 viruses, CDC continues to recommend the use of oseltamivir and zanamivir for the treatment or prevention of influenza. Use of amantadine or rimantadine is not recommended.
