Pandemic Flu Containment Measures Bought Valuable Time

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Pandemic Flu Containment Measures Bought Valuable Time, Vietnam Study Suggests.

ScienceDaily (May 21, 2010) — Containment measures introduced in Vietnam to

prevent the spread of the 2009 pandemic H1N1 influenza did not succeed in

halting the virus, but may have bought health services and clinical researchers

valuable time, according to research carried out at the Wellcome Trust Major

Overseas Programme in Ho Chi Minh City, Vietnam.

The study also showed that patients with mild disease responded favourably in

terms of viral clearance -- and hence reduced transmission of the virus -- to

oseltamivir, the most commonly-used antiviral drug, when given in the first 3-4

days of illness.

On 27 April 2009, when the World Health Organization declared Phase 4 in

response to the H1N1 influenza virus -- indicating a significant increase in

risk of a pandemic -- the Vietnamese Ministry of Health mandated body

temperature scans and symptom questionnaire screening of international

travellers arriving at the airport, and in-hospital isolation of suspected

cases.

Vietnam reported its first case of infection on 31 May 2009, in a Vietnamese

student returning to Ho Chi Minh City from the United States five days earlier.

Twelve days later on 12 June, Hanoi reported its first cases. By February 2010,

there had been over 11,000 confirmed cases in the country, including 58

confirmed deaths.

Researchers from the Wellcome Trust Major Overseas Programme and Oxford

University Clinical Research Unit at the Hospital for Tropical Diseases in

Vietnam analysed reports from the Ministry of Health and relevant health

authorities, and clinical and laboratory data for people infected with the 2009

influenza virus A (H1N1) and isolated in hospital. The researchers used these

reports to reconstruct the initial outbreak and the establishment of community

transmission in Ho Chi Minh City. The results are published in the open-access

journal PLoS Medicine.

The researchers found that in the two months from 26 May to 24 July, 200

positive cases were identified through airport screening, but that around 40

pre-symptomatic -- and hence undetectable -- individuals would have arrived at

the airport in the same period.

" We don't know how many true cases of H1N1 infection there were in Vietnam

during this period, but it is clear to us from mathematical analysis that the

epidemic in Ho Chi Minh City was not containable, " says lead author Dr Rogier

van Doorn from the University of Oxford,.

However, the study showed that the intervention strategies put in place in Ho

Chi Minh City by the Vietnamese authorities -- airport screening, isolation, and

treatment -- shortened the chances of infected individuals transmitting the

virus to others. In addition, as passengers on one in six incoming flights heard

announcements suggesting self-quarantine, mask wearing, and guidelines for

monitoring personal health, this increased patients' likelihood of hygienic

behaviour and self-reporting if they had influenza-like symptoms.

" The containment measures seemed to delay the onset of large-scale transmission

by at least three weeks, " says corresponding author Dr Maciej Boni, also from

the University of Oxford,. " This may not sound like a lot, but in a country like

Vietnam this bought valuable time for the local health services, laboratories

and travel authorities to understand what was happening and start logistical

preparations for the pandemic response. The pandemic was mild and no intense

response was required, but this may have just been lucky. "

The authors say that it is difficult to draw conclusions from this study as to

the effectiveness of similar measures being able to contain future pandemics.

" The problem is that you don't know what kind of virus you're dealing with at

the moment that measures need to be installed, " explains Dr van Doorn. " In

hindsight one could say that too much effort was put into containment efforts

for this virus, but at the time the decisions were made, they were very

sensible. Active case-finding and treatment of severe cases may have been a

better approach for this virus, but again, we can only see this in hindsight.

" For a different type of virus, it will depend what we turn out to be dealing

with. Human H5N1 'bird flu' cases are usually very severe, but not very

transmissible, so they are easy to find and contain, and our strategies of drug

treatment, contact tracing, isolation, poultry vaccination seem to have made

such outbreaks manageable so far. "

Professor Tran Tinh Hien, Director of Clinical Research at the Oxford University

Clinical Research Unit, Hospital for Tropical Diseases, believes the study

highlights the success of the response of the clinical research community to the

outbreak.

" One of the most important features of this work was the speed with which we

were able to establish multidisciplinary clinical research studies in response

to a rapidly emerging problem, " he commented. " Clinical research has become

increasingly complex and therefore slow. This work shows that it is possible to

respond quickly, safeguard patients and learn crucial lessons for the future. "

The study was funded by the Wellcome Trust and the UK Medical Research Council,

with support from the South East Asia Infectious Disease Clinical Research

Network. Story Source:

Adapted from materials provided by Wellcome Trust, via EurekAlert!, a

service of AAAS.

http://www.sciencedaily.com/releases/2010/05/100518180854.htm