What is this outbreak?
Basic virus type is H1N1
This is a common type of flu, but
Immunity is based on the individual strain, not major type
Being called Swine Flu as shorthand
Actually a combination (reassortment) virus
At least 2 swine virus components
1 avian virus component (This is NOT Avian Flu)
Human virus components
Most cases have had no contact with swine
Implies that there is human to human transmission
Cases as of April 28, 2009
US Confirmed: 65 (median age 16 yrs)
California 10 (3 hospitalized)
Kansas 2
New York City 45
Ohio 1
Texas 6
Indiana 1 (not in total as not yet CDC confirmed)
Mexico Confirmed: 26
Suspect cases variously reported over 2000 in 19 of Mexicos 32 states
Other Confirmed: Canada (6), New Zealand (3), Israel (2), UK (2), Spain (2), Costa Rica (1)
Official Status
WHO (Pandemic Phase) updated 4/27
Phase 4: Small clusters with human to human transmission, but spread is highly localized suggesting that the virus is not well adapted to humans
WHO has declared a Public Health Emergency of International Concern (4/26)
U.S. Government
Pandemic Response Stage 0
HHS declared Public Health Emergency (4/26)
CDC Interim Director noted that U.S. Response Staging is based on virulence (and other factors) and not only the geographic spread.
How is this Flu different?
Little immunity in the general population
Increased attack rates
Flu rates 3 to 4 times the normal in Mexico (various cities)
Underreporting may be a big issue
but flu always underreported
Possibly increased severity
Hospitalization and mortality rates reported as high in Mexico
US cases have been mild to moderate with no deaths
This is Flu, not SARS
A person does not have to have symptoms to be infectious
This flu, like most flu, is infectious 24+ hours before symptoms
There may be asymptomatic or very mildly symptomatic cases who are infectious nonetheless
So far, this does not appear to have as high a mortality rate
How is this flu similar to usual flu?
Transmission:
Respiratory secretions: surfaces/airborne droplets
Incubation period / Infectivity period:
Incubation 1 to 4 days, very rarely up to 7 days or longer
People are infectious from 24+ hours before symptoms start and up to 7 days after onset of symptoms
Symptoms
Fever/chill, cough, sore throat, body aches, headache, fatigue
Effects can be much worse in those with other diseases
Treatment
Antivirals (oseltamivir or zanamivir only) appear effective
Is this THE Pandemic Flu we all fear?
Maybe
Swine Flu is very contagious (as are most new flu strains)
Populations are not immune to this strain
Has already demonstrated international spread
Some, very preliminary, evidence of high virulence (relatively high death rate in Mexican cases)
Large numbers of cases being diagnosed in Mexico
Maybe not
The season is not conducive to sustained transmission
Cases in US have had low to moderate virulence
Epidemic may have been smoldering for several weeks in locations outside Mexico without explosive growth rates
What should our organization do?
Prior Pandemic Flu preparation is valuable
even if this is not pandemic flu
Refresh training on controlling secretions
Cover mouth when coughing/sneezing
Use paper tissues and throw them away when done
Wash hands frequently and/or use a hand sanitizer
Always wash hands immediately before and after touching eyes, nose, or mouth
Tell employees not to come to work sick!
But dont go to a clinic/hospital without contacting the facility first
you dont want to transmit to/from others
If an employee has close contact with someone meeting criteria for suspected, probable, or confirmed illness, ideally they should not return to work for 7 days after last contact or after contacts symptoms have cleared (added 4/28)
Should we change travel/meeting plans?
In general:
Not yet, but prudent to develop contingency plans
Emphasize basic infection control for air travel
Use hand sanitizers frequently
Avoid shared magazines / blankets / pillows / etc.
Dont travel if you have respiratory illness symptoms
International Travel (updated 4/28)
CDC has advised delay of nonessential travel to Mexico
Many nations are screening travelers to/from North America; some screening all travelers
Screening, when used, is usually a temperature screen
Elevated temp can result in further eval or quarantine/isolation
Should we change general operations?
For everyone:
Review and update pandemic plan
For sites not in proximity to known cases
No change in operations
Reassure staff that management is monitoring closely
Encourage review of respiratory secretion precautions
Should we change general operations?
For sites in proximity to known cases
No change in operations
Minimize large gatherings or even small meetings in enclosed locations
Ensure all personnel review respiratory precautions
Have plans for handling ill employees:
Do not to come to work with respiratory symptoms or if closely exposed to someone with a respiratory illness at home (unless medically cleared)
Institute specific plans for handling personnel developing symptoms while at work
Follow local public health guidelines, including having plans to screen employees if directed by local public health
Additional Information
Additional Information for Medical Professionals
Interim Case Definition Suspected (4/28)
a person with acute febrile respiratory illness
With onset within 7 days of close contact with a person who is a confirmed case of swine influenza A (H1N1) virus infection, or
With onset within 7 days of travel to community either within the United States or internationally where there are one or more confirmed swine influenza A(H1N1) cases, or
resides in a community where there are one or more confirmed swine influenza cases.
*Acute febrile respiratory illness is defined as recent onset of a fever with at least two of the following: Rhinorrhea or nasal congestion, sore throat, cough.
**Close contact is defined as: within about 6 feet of an ill person who is a confirmed or suspected case of swine influenza A (H1N1) virus infection during the cases infectious period.
Interim Case Definition Probable (4/28)
A person with an acute febrile respiratory illness who is:
positive for influenza A, but negative for H1 and H3 by influenza RT-PCR, or
positive for influenza A by an influenza rapid test or an influenza immunofluorescence assay (IFA) plus meets criteria for a suspected case
*Acute febrile respiratory illness is defined as recent onset of a fever with at least two of the following: Rhinorrhea or nasal congestion, sore throat, cough.
Interim Case Definition Confirmed (4/28)
A person with an acute respiratory illness* with laboratory confirmed swine influenza A (H1N1) virus infection at CDC by one or more of the following tests:
real-time RT-PCR
viral culture
*Acute febrile respiratory illness is defined as recent onset of a fever with at least two of the following: Rhinorrhea or nasal congestion, sore throat, cough.
Utility of Screening Tests
Most screens are A+B tests
If positive:
Treat with anti-virals
Send to State Lab
Routine hospital/commercial labs have little to offer
If Screen can type as B (not common):
Positive B and negative A rules out current swine flu strain
Positive A must be handled as above
State labs can rule out H1N1-swine
but cannot further type
Sample must be sent to CDC for swine flu confirmation
CDC may distribute PCR primers to states in near future
Severity Discrepancy
CDC very clear that nothing should be made of apparent discrepancy in severity between Mexico and US.
May simply be a denominator issue (Mexico has had many, many more cases than US)
CDC said (4/26 press briefing) that US should be prepared to expect Swine-flu related deaths in the near future
Vaccine Issues
CDC has found little antigenic cross-protection from current flu vaccine
Vaccine programs are not indicated to prevent this flu
Being vaccinated however, can help rule out seasonal flu if ill
Degree of natural immunity not well characterized
CDC actively investigating Swine Flu vaccine
Referring to problems with 1976 Swine Flu issues:
Much has changed in vaccine science since 1976
US has much more experience with vaccine production / QC
If a vaccine is determined to be advisable:
Difficult to determine duration for preparation as much is determined by how fast virus grows
New technologies, such as cell-based vaccine production, might be available, but none are FDA approved