27 April

Monday 10pm

WHO Raises Pandemic Alert to Phase 4 due to swine influe= nza A (H1N1); Infections and some Deaths Continue in Mexico, US Cases Increase = to 40 (none fatal), and Confirmed Case(s) Occur in Spain and Scotland. Will th= is Virus Become Established in the Southern Hemisphere by their Upcoming Flu Season (June-August, 2009)?

The Director-General of the World Health Organization, D= r. Margaret Chan, declared in a one-page statement posted April 27^{th on
the WHO website (www.who.int/mediacentre/news/statements/2009/h1n1_20090427/en=
/index.html}

that on the advice of the WHO Emergency Committee advisi= ng her on the epidemic of swine influenza A (H1N1), she raised the level of influenza pandemic alert from the current Phase 3 to Phase 4.

Phase 4 is characterized by verified human-to-human transmission of an animal or human influenza reassortant virus able to cause “community-level outbreaks” …Phase 4 indicates a signific= ant risk of a pandemic but does not necessarily mean that a pandemic is a foreg= one conclusion.”

An excellent one-page color diagram with the latest (this week) definitions of WHO phases of pandemic aler= t are posted on their website at: www.who.int/csr/disease/avian_influenza/phase/en/index.html=

In the USA a total of 40 cases of lab-confirmed swine influenza A (H1N1) were posted on the daily CDC updated website. None of these cases have been fatal, and nearly all have recovered without hospitalization. The 20 new cases reported since Sunday were in the NY City (Queens) high school cluster that included persons who had traveled to Mexico.

In my opinion, there will be deaths in the USA due to this novel virus, as has occurr= ed in Mexico.=

We known the virus is reported to be genetically identic= al in both countries. The most likely explanation at this point for the absenc= e of deaths in the USA, in contrast to Mexico, is= that many more infections have occurred in Mexico. If the US had as many infections with this new vi= rus as Mexico has had, then t= here would already be some deaths in the USA.

To illustrate by a purely hypothetical example: If a nov= el virus infects 1,000 people in country A, and kills 10 of these 1,000 person= s, then it has a case-fatality rate (CFR) of 10/1000 =3D 1% (or 1 in 100). Thu= s, if there are only 40 persons infected with this same virus in country B, it is= not surprising that none of these 40 persons have died.

In Europe, one lab-confirmed case was reported from Spain (non-fatal), and two confirmed cases= were reported in Scotland= (where both were reported to be recovering well in hospital).

The Food and Drug Administration (FDA) posted a 2-page document of far-reaching importance on their website (www.fda.gov) April 27 titled “FDA Authorizes Emergency Use of Influenza Medicines, Diagnostic Test(s) in Resp= onse to Swine Flu Outbreak in Humans”.&nb= sp; In response to requests from the CDC the FDA reported issuing “= ;EMERGENCY USE AUTHORIZATIONS (EUAs) to expand the availability of anti-influenza drugs and new lab diagnostic tests for this swine flu virus: http://www.f= da.gov/bbs/topics/NEWS/2009/NEWO2002.html

For example, “The EUAs allow for Tamiflu also to be used to treat and prevent influenza in children under 1.” Tamiflu (oseltamivir, an oral anti-influenza drug) is not FDA-licensed for use in children under one year. But now it can be used for children < 1 year of= age with this FDA Emergency Use Authorization (EUA).

In addition, this FDA EUA allows for both the oral Tamif= lu (oseltamivir) and the inhaled anti-flu drug zanamivir (Relenza) to be “distributed to large segments of the population without complying wi= th the label requirements otherwise applicable to dispensed drugs, and accompa= nied by written information pertaining to the emergency use. They may also be distributed by a broader range of health care workers, including some public health officials and volunteers, in accordance with applicable states and l= ocal laws and/or public health emergency responses.”

Moreover this FDA EUA “allows the CDC to distribute the swine flu test to public health and other qualified laboratories that h= ave the needed equipment and the personnel who are trained to perform and inter= pret the results.”

Will this Novel Swine Flu Virus Become Established in th= e Southern Hemisphere by their Upcoming Flu Season (June-August, 2009)?

One can hope that this novel influenza virus will sharply decrease its transmission during the upcoming warmer (summer) months June-August in the northern hemisphere, by analogy to seasonal human influe= nza, and the SARS coronavirus in 2003.

At the same time, however, it is critically important to recall that, generally speaking, the SOUTHERN Hemisphere will be having their upcoming winter influenza season during these same June-August months (while recognizing that some natio= ns have two seasonal peaks of influenza (e.g., Hong Kong) and others close to = the equator may have some cases year-round).

Thus, if the current novel swine flu virus spreads betwe= en now and the upcoming influenza season in the Southern Hemisphere (June-Augu= st 2009), then conceivably widespread “community-level outbreaks” = due to sustained human-to-human transmission could occur in two or more nations= in one WHO region (i.e., the defining characteristic of WHO Phase 5) in the SOUTHERN Hemisphere.

If this does occur in the SOUTHERN Hemisphere, th= en in the Northern Hemisphere’s next autumn-winter (September 2009-March 2010), this swine flu virus H1N1, or an evolved/mutated version, could be transmitted back with subsequent WHO Phase 5 spread, or even true pandemic spread i.e., WHO Pandemic Phase 6.

Thus, it is in everyone’s interest to maximize eff= orts immediately to diagnose and treat each patient anywhere in the world with t= his novel swine flu virus infection, and prevent (or mitigate) the transmission= of this virus anywhere it occurs as soon as possible.

Daniel R. Lucey, MD, MPH

EROne Institutes, Department of emergency medicine<= /o:p>

Washingt= on Hospital Center

Adjunct Professor of Microbiology and immunology

Georgetown University m= edical Center, Washington,= DC

Website for this posting: www.BePast.org (requires Internet Explorer)

e-mail: DRL23@Georgetown.edu