Published Date: 2009-11-25 16:00:10
Subject: PRO/AH> Influenza pandemic (H1N1) 2009 (115): USA (WV) repeat infection
Archive Number: 20091125.4047

INFLUENZA PANDEMIC (H1N1) 2009 (115): USA (WEST VIRGINIA) REPEAT INFECTION
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Comments re: Influenza pandemic (H1N1) 2009 (115): USA (WV), repeat
infection 20091124.4039
----------------------------------------------------------------------

[1]
Date: Tue 24 Nov 2009
From: Allen Lenoir <alenoir@bioterrorism-vaccines.com> [edited]


Comment
-------
I've seen H1N1 patients with severe leukopenia and lymphocytopenia
during the acute infection. Such severe lymphocytopenia might
interfere with the ability to mount an adequate immune response. I've
also wondered what effect prompt antiviral therapy might have on the
immune response.

--
Allen Lenoir, MD
Miami, FL
USA
<alenoir@bioterrorism-vaccines.com>

*****
[2]
Date: Wed 25 Nov 2009
From: Julian Tang <julian_wt_tang@nuhs.edu.sg> [edited]


Comment
-------
The ProMED-mail report entitled "Influenza pandemic (H1N1) 2009
(114): USA (WV), repeat infection" regarding Dr Parsons reinfection
with A/H1N1/2009 is useful and I would encourage her to publish these
findings, if only to fill the data gap on this subject to which Dr
Gupta alludes.

Studies in humans (as opposed to mouse models) performed over 20
years ago with natural infection by different influenza A subtypes
suggest that influenza reinfection is not so uncommon, as the CDC has
indicated: rates of reinfection with influenza A/H3N2 have been as
high as 63 percent in consecutive seasons in one family study, which
included young children (1976/77 and 1977/78) (1); with influenza
A/H2N2 as high as 27 percent (17/62) within 6 months (2). This same
report also found a reinfection rate of 17 percent with A/H3N2
amongst students in 1970 and of 32 percent and 69 percent in 2 groups
of students in 1972, and of 32 percent in 1983 -- with the A/H3N2
viruses showing various degrees of antigenic drift. With A/H1N1,
reinfection rates of 9.3 percent and 20 percent were reported for 2
other student groups in 1980 (2).

Given the above, there may be no reason to expect this pandemic
human-adapted swine influenza virus A/H1N1/2009 to behave any
different?

The related question, of course, is how long one can expect the
A/H1N1/2009 vaccine-induced immunity to last -- though of course,
running parallel to this is ongoing A/H1N1/2009 viral mutation that
may require a change in vaccine antigen-specificity and
re-immunisation at a later date, anyway.

References
---
1. Sonoguchi T, Sakoh M, Kunita N, et al: Reinfection with influenza
A (H2N2, H3N2, and H1N1) viruses in soldiers and students in Japan. J
Infect Dis. 1986 Jan; 153(1): 33-40 [abstract available at
<http://www.ncbi.nlm.nih.gov/pubmed/3941288>].
2. [No authors listed] Reinfection with influenza. Lancet. 1986 Aug
16; 2(8503): 372-4.

--
Dr Julian W Tang PhD, MRCP, FRCPath
Consultant/ Virologist
Division of Microbiology/Molecular Diagnostic Centre
Department of Laboratory Medicine
National University Hospital
5 Lower Kent Ridge Road
Singapore 119074
<julian_wt_tang@nuhs.edu.sg>

[Out correspondents suggest 2 explanations for this case of pandemic
(H1N1) 2009 virus reinfection in a mother and son. Dr Lenoir's
observations suggest that reinfection may on occasion be a
consequence of transient immune suppression, whereas Professor Tang
cites evidence that reinfection may occur more frequently than
currently supposed. These issues are relevant to the strategy of
vaccination and further comments would be welcomed. - Mod.CP]

See Also

Influenza pandemic (H1N1) 2009 (114): USA (WV), repeat infection 20091124.4039
Influenza pandemic (H1N1) 2009 (113): Saudi Arabia, Hajj fatalities
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Influenza pandemic (H1N1) 2009 (112): Canada (MB), vaccine reaction
20091121.4009
Influenza pandemic (H1N1) 2009 (111): Norway, mutants 20091121.4005
Influenza pandemic (H1N1) 2009 (110): UK (Wales), Tamiflu resistance
20091120.4000
Influenza pandemic (H1N1) 2009 (100): Ukraine (DT) 20091114.3940
Influenza pandemic (H1N1) 2009 (90): Venezuela, Yanomami 20091105.3820
Influenza pandemic (H1N1) 2009 (80): Ukraine susp. RFI 20091031.3764
Influenza pandemic (H1N1) 2009 (70): Nepal 20091016.3563
Influenza pandemic (H1N1) 2009 (60): bacterial coinfection 20090930.3410
Influenza pandemic (H1N1) 2009 (50): oseltamivir-resistance 20090917.3260
Influenza pandemic (H1N1) 2009 (40): global update 20090906.3138
Influenza pandemic (H1N1) 2009 (30): assumptions 20090813.2879
Influenza pandemic (H1N1) 2009 (20): Peru, 33 percent asymptomatic
20090730.2668
Influenza pandemic (H1N1) 2009 (10): vaccine 20090720.2577
Influenza pandemic (H1N1) 2009 - Viet Nam: patient data 20090708.2450
...................................cp/mj/lm

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