On December 23rd, CDC released another statement about the evolving situation with swine-origin triple reassortant influenza A(H3N2) virus in the United States. Three more human infections, two of which associated with a daycare in West Virginia. The latter is of greater concern than the former due to probable human-human transmission. Time delays between submission of samples and public report by CDC remain high:
(Case A) Indiana, no evidence of human-human transmission- exposure from swine.
- Day 0 (Oct 20th). Patient symptomatic, hospitalized for 4 days.
- Day 2 (Oct 22nd). Influenza-positive per in-house hospital laboratory testing.
- Day 8 (Oct 28th). Indiana State Public Health Laboratory: "inconclusive influenza A virus".
- Day 11 (Oct 31st). CDC confirms via genomic sequencing presence of "A(H3N2)v" (formerly known as S-OtrH3N2)
- Day 64 (Dec 23rd). CDC publicly releases the above information.
- Time delta: state public health recognition of unusual virus= 8 days
- Time delta: clinical processing of patient to CDC awareness= 11 days
- Time delta: CDC issuance of warning to the public= 64 and 56 days from initial clinical processing of the patient and state notification to CDC, respectively
(Cases B) West Virgina, evidence of human-human transmission.
- Day 0 (Nov 12th, approximate). Pediatric patient recognized symptomatic by parents.
- Day 7 (Nov 19th). Patient, who was already hospitalized for an unrelated issue, develops fever.
- Day 9 (Nov 21st). Sample taken. In-house hospital laboratory discovers sample is positive for influenza A. Patient discharged home.
- ... No further information regarding when West Virginia's state laboratory or CDC processed the sample, which was A(H3N2)v-positive.
- Time delta: state public health recognition of unusual virus= unknown
- Time delta: clinical processing of patient to CDC awareness= unknown
- Time delta: CDC issuance of warning to the public= 34 days from initial clinical processing of the patient (approx. Nov 19th)
(Case C) West Virginia, same cluster / thread.
- Day 0 (Nov 29th). 2nd child at daycare center ill.
- Day 9 (Dec 7th). West Virginia Office of Laboratory Services processes sample as "inconclusive"- forwards on to CDC. This patient was part of a retrospective assessment, where clinical processing did not occur.
- .. No further information regarding when CDC processed the sample, which was A(H3N2)v-positive.
- Time delta: CDC issuance of warning to the public= 34 days from state public health laboratory processing of the sample to CDC issuance of public warning
The key point is of course, we only know what we are able to know. Our team leaned into the discussion in November to ensure CDC was aware we were 1) monitoring the situation and 2) are carefully documenting their performance in coupling warning to response. And quietly behind the scenes we are engaging clinical practitioners in an effort to encourage more sampling among symptomatic patients who were vaccinated for this season. We expect the predominance of this focus to be on pediatric patients, however we are not seeing social sensitization yet among pediatricians. Messaging from CDC requires clarification and guidance regarding when to sample.
Currently, we are observing between large time deltas between clinical processing of these patients and CDC's issuance of public warning. It is our opinion that if A(H3N2)v suddenly displaces current seasonal A/H3N2 or gains significant prevalence, the first point of recognition may be an abruptly overwhelmed pediatric medical infrastructure versus dramatically time-delayed reporting from CDC.
The observations of public health performance during the 2009 influenza pandemic begin to repeat themselves...