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Does Infection with the Pandemic H1N1 Influenza A Virus/2009 Confer Protection Against Re-Infection? Print E-mail
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อาทิตย์, 11 ตุลาคม 2009

8 October 2009

From www.bepast.org

BY Daniel R. Lucey, MD, MPH

EROne Institutes, Department of Emergency Medicine

 Washington Hospital Center

 Department of Microbiology and immunology

 Georgetown University Medical Center, Washington, D.C.

 Website for this posting: www.BePast.org



In an extensive interview with USA Today’s Editorial Board, Dr. Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases (NIAID) at the National Institutes of Health (NIH) was asked “If you suspect that you’ve been exposed to swine flu, should you still get vaccinated?”(See “Swine Flu: What You Need to Know”, October 7, page 9A).

Dr. Fauci’s was:  “Yes, because you just don’t know. There are a lot of viruses out there that aren’t necessarily influenza. If I had a laboratory test that definitively said, yes, you did get infected with H1N1, I would tell you no, don’t get vaccinated because natural vaccination is the best vaccine you can give for yourself. But unless you’re sure, I would go ahead and take it.”

Today’s (Oct 8) NY Times front page contains a detailed article titled “Areas Hard Hit by Flu in Spring See Little Now” by Anemona Hartocollis and Donald G. McNeil, Jr.  (p.A1 and A4).  The pandemic H1N1/2009 influenza A experience in New York City is cited:

   “…New York City health officials now believe that while 10 percent to 20 percent of New Yorkers were reportedly ill with flu last spring, as many as 20 percent to 40 percent may have been exposed to the disease and developed immunity that has prevented it from spreading”.

 “Although it is too early to be sure, they said, the high level of immunity may mean that the second wave of swine flu infection ends up being far less extensive than expected.”

   “The immunity theory has gained enough credence that Dr. Thomas A. Farley, New York City’s health commissioner, put it forward at a conference on the national preparations for H1N1 last Friday in New York, led by Kathleen Sebelius, the health and human services secretary, and Dr. Thomas R. Frieden, director of the disease control centers…”

Unfortunately, routine laboratory tests with a rapid turn-around time are not available to prove whether or not protective immunity is certain in persons who were already infected and recovered from this pandemic influenza A H1N1/2009 virus. If such protection could be proven, then indeed such “immune survivors” might not need to receive the pandemic flu vaccine, take anti-influenza drugs, or perhaps require the same personal protective equipment (PPE) as non-immune persons. 

This writer, along with many others such as John Barry, has raised this concept previously. For example, in a letter to the Washington Post three years ago, on April 29, 2006 and in this www.BePast.org Newsletter space on May 2, 2006, and again three years later on May 4, 2009, as well as in a slide presentation Feb 24, 2007 at the first International Meeting on Emerging Diseases (IMED 2007) in Austria and in a similar presentation to the FDA (CDER) on April 30, 2007. 

The influenza historian John Barry, and colleagues, concluded in a paper in the 15 Nov 2008 Journal of Infectious Diseases that “Exposure to influenza in the spring and summer of 1918 provided mortality and morbidity protection during the fall pandemic wave. The intensity of the first wave may have differed across US cities and countries and may partly explain geographic variation in pandemic mortality rates in the fall. Pandemic preparedness plans should consider that immune protection could be naturally acquired during the first wave of mild influenza illness.” 

In my opinion, we can hope that both epidemiological data and immunological data will be forthcoming this fall 2009 and in the winter 2010 that will either prove or disprove this immunity hypothesis regarding pandemic influenza.  If so, such evidence should help national and international preparedness efforts for future waves of this pandemic flu virus, and future influenza pandemics.



 1.       Barry JM, Viboud C, Simonsen L. Cross-Protection between successive waves of the 1918-1919 Influenza Pandemic: epidemiological Evidence from US Army Camps and from Britain. J Infectious Diseases 2008; 198: 1427-34.

 2.       Lucey D. Letter to the Editor. The Washington Post. April 29, 2006.

 3.       Lucey D.  “Will Persons who recover from pandemic flu be immune (protected) from re-infection, and thus able to return to work even without vaccination or antiviral prophylaxis”? Washington Newsletter. May 2, 2006. www.BePast.org. Accessed on October 8, 2009.

 4.       Lucey D.  “Immune Survivors in the Management of Pandemic Influenza”. First International Meeting on Emerging Diseases (IMED 2007) and Surveillance. Vienna, Austria. Feb 24, 2007.

 5.        Lucey D. “Immune Survivors in the Management of Pandemic Influenza”  US Food and Drug Administration (FDA)/CDER. April 30, 2007. Bldg 29, Bethesda, Maryland. (DVD available---copy made by CDER  hosts for the FDA Commissioner’s Office).

6. Lucey D.  “Will survivors of the New Influenza a (H1N1) 2009 virus be Immune to Re-Infection, Protected from Severe Disease if Infected with a Related Flu Virus, and/or Able to donate Immune Plasma?” Washington Newsletter May 4, 2009 posted on www.BePast.org. accessed on October 8, 2009.


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