単純な方法がインフルエンザを防ぐ

単純な方法がインフルエンザを防ぐ
画像 英国政府は将来の流行に備えて抗ウイルス剤の備蓄を2倍に増やすということだが、もっと簡単で安価な方法にプライオリティを与えるべきである。オーストラリアのボンド大からの報告。
 新型インフルエンザの流行は近い将来には必然的なことであり、SARS などの致死性の呼吸器疾患の蔓延も懸念される。ワクチンと抗ウイルス薬ではインフルエンザの流行阻止には不充分との証拠も増えつつある。
 呼吸器感染防止への簡単な物質的な手段の効果について、51の最新の研究がある。いくつかの研究が2003年の特に南東アジアのSARS流行に集中してなされた。1日10回以上の手洗いとマスク、手袋とガウン、患者の隔離、これらの組み合わせが重要な防御手段であると結論された。
 インフルエンザに関して336もの試験がWHOに登録されているが、物理的な遮断方法についての研究はたった3つしかない。もっと多くの研究が必要ではないだろうか?
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Last Updated: Wednesday, 28 November 2007, 00:09 GMT
Simple measures 'may thwart flu'
http://news.bbc.co.uk/2/hi/health/7114517.stm

Lab test
Drugs play an important part in UK planning

Simple physical measures, such as handwashing and wearing masks, could play a key role in blocking the spread of a flu pandemic, say researchers.

The UK government is doubling its stockpile of antiviral medicines in preparation for any future pandemic.
But researchers believe simple, low- cost physical measures should be given higher priority.
The study, led by Australia's Bond University, features online in the British Medical Journal.
Scientists believe a flu pandemic is inevitable at some point in the future. There are also concerns about the spread of potentially fatal respiratory diseases such as Sars.
There is mounting evidence to suggest the use of vaccines and antiviral drugs will be insufficient to interrupt the spread of flu.
The latest research examined 51 studies on the effect of simple physical measures on preventing respiratory infections. Several of the studies focused specifically on the Sars outbreak in South-East Asia in 2003.
The researchers found handwashing and wearing masks, and gloves and gowns all had a positive effect - and were even more effective when combined.
The researchers concluded that, in combination with measures such as isolation of infected patients, they could potentially provide an important defence against a pandemic.
More research needed
They argue that national governments should carry out more research into their use.
Researcher Dr Tom Jefferson said: "Worried about the flu? Then we have some good news for you.
"Wash your hands, and if it is a really bad epidemic avoid contact with people and keep your distance. You may even consider wearing paper masks and disposable gloves. They work.
"Soap and water is cheap and if you come from a poor country it could save your life or your baby's life."
Dr Martin Dawes, a family medicine expert at McGill University, Montreal, said there had been a lack of research into the best way to prevent spread of respiratory pandemics.
Although 336 trials on influenza have been registered on the World Health Organization international clinical trials registry, only three trials are about reducing transmission by keeping a physical distance from patients, or using barrier methods.
He said: "Because pandemic flu is such a potentially catastrophic event, governments worldwide should have commissioned such a review many years ago and not have left it to the academic community to take the lead."
Professor John Oxford, chair of the Hygiene Council and an expert in respiratory diseases based at Queen Mary College School of Medicine, agreed that barrier methods had a role to play.
However, he said the UK government was right to emphasise the primary importance of stockpiling antivirals and vaccines.
"Any suggestion that a bit of handwashing could replace the need for vaccines and antiviral drugs would be dangerous and foolhardy."
# The Department of Health is launching a campaign to reduce the spread of colds, flu and other viruses.
The Catch It, Bin It, Kill It campaign emphasises the need to cover your nose and mouth with a tissue when you cough and sneeze, dispose of the tissue as soon as possible after use, and clean your hands at the first available opportunity.
------------------------------------------
BMJ, doi:10.1136/bmj.39393.510347.BE (published 27 November 2007)
Research
Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review

Tom Jefferson, coordinator1, Ruth Foxlee, trials search coordinator2, Chris Del Mar, dean3, Liz Dooley, review group coordinator4, Eliana Ferroni, researcher5, Bill Hewak, medical student3, Adi Prabhala, medical student3, Sree Nair, professor of biostatistics6, Alex Rivetti, trials search coordinator1

1 Cochrane Vaccines Field, Alessandria, Italy, 2 Cochrane Wounds Group, Department of Health Sciences, University of York, 3 Faculty of Health Sciences and Medicine, Bond University, Gold Coast, 4229, Qld, Australia, 4 Cochrane Acute Respiratory Infections Group, Faculty of Health Sciences and Medicine, Bond University, 5 Public Health Agency of Lazio Region, Rome, 6 Department of Statistics, Manipal Academy of Higher Education, Manipal, India

Correspondence to: C Del Mar cdelmar@bond.edu.au

Objective To systematically review evidence for the effectiveness of physical interventions to interrupt or reduce the spread of respiratory viruses.

Data extraction Search strategy of the Cochrane Library, Medline, OldMedline, Embase, and CINAHL, without language restriction, for any intervention to prevent transmission of respiratory viruses (isolation, quarantine, social distancing, barriers, personal protection, and hygiene). Study designs were randomised trials, cohort studies, case-control studies, and controlled before and after studies.

Data synthesis Of 2300 titles scanned 138 full papers were retrieved, including 49 papers of 51 studies. Study quality was poor for the three randomised controlled trials and most of the cluster randomised controlled trials; the observational studies were of mixed quality. Heterogeneity precluded meta-analysis of most data except that from six case-control studies. The highest quality cluster randomised trials suggest that the spread of respiratory viruses into the community can be prevented by intervening with hygienic measures aimed at younger children. Meta-analysis of six case-control studies suggests that physical measures are highly effective in preventing the spread of SARS: handwashing more than 10 times daily (odds ratio 0.45, 95% confidence interval 0.36 to 0.57; number needed to treat=4, 95% confidence interval 3.65 to 5.52); wearing masks (0.32, 0.25 to 0.40; NNT=6, 4.54 to 8.03); wearing N95 masks (0.09, 0.03 to 0.30; NNT=3, 2.37 to 4.06); wearing gloves (0.43, 0.29 to 0.65; NNT=5, 4.15 to 15.41); wearing gowns (0.23, 0.14 to 0.37; NNT=5, 3.37 to 7.12); and handwashing, masks, gloves, and gowns combined (0.09, 0.02 to 0.35; NNT=3, 2.66 to 4.97). The incremental effect of adding virucidals or antiseptics to normal handwashing to decrease the spread of respiratory disease remains uncertain. The lack of proper evaluation of global measures such as screening at entry ports and social distancing prevent firm conclusions being drawn.

Conclusion Routine long term implementation of some physical measures to interrupt or reduce the spread of respiratory viruses might be difficult but many simple and low cost interventions could be useful in reducing the spread.

Although respiratory viruses usually cause minor disease, epidemics can occur. Mathematical models estimate that about 36 000 deaths and 226 000 admissions to hospital in the United States annually are attributable to influenza,1 and with incidence rates as high as 50% during major epidemics worldwide, respiratory viruses strain health services,2 are responsible for excess deaths,2 3 and result in massive indirect costs owing to absenteeism from work and school.4 Concern is now increasing about serious pandemic viral infections. In 2003 an epidemic of the previously unknown severe acute respiratory syndrome (SARS) caused by a coronavirus affected about 8000 people worldwide, with 780 deaths (disproportionately high numbers were in healthcare workers), and causing a social and economic crisis, especially in Asia.5 A new avian influenza pandemic caused by the H5N1 virus strain threatens greater catastrophe.6

High viral load and high viral infectiousness probably drive virus pandemics,7 hence the need for interventions to reduce viral load. Mounting evidence suggests, however, that single measures, particularly the use of vaccines or antivirals, will be insufficient to interrupt the spread of influenza. Agent specific drugs are also not available for other viruses.7 8 9 10

A recent trial found handwashing to be effective in lowering the incidence of pneumonia in the developing world.w1 Clear evidence has also shown a link between personal (and environmental) hygiene and infection.11 We systematically reviewed the evidence for the effectiveness of combined public health measures such as personal hygiene, distancing, and barriers to interrupt or reduce the spread of respiratory viruses.12 13 We did not include vaccines and antivirals because these have been reviewed.4 10 14 15 16 17 18

We considered trials (individual level, cluster randomised, or quasirandomised), observational studies (cohort and case-control), and any other comparative design in people of all ages provided some attempt had been made to control for confounding.

We included any intervention to prevent the transmission of respiratory viruses from animals to humans or from humans to humans (isolation, quarantine, social distancing, barriers, personal protection, and hygiene) compared with no intervention or with another intervention. We excluded vaccines and antivirals.

The outcome measures were deaths; numbers of cases of viral illness; severity of viral illness, or proxies for these; and other measures of burden, such as admissions to hospital.

Search strategy
We searched the Cochrane Central Register of Controlled Trials (Cochrane Library issue 4, 2006), Medline (1966 to November 2006), OldMedline (1950-65), Embase (1990 to November 2006), and CINAHL (1982 to November 2006). See bmj.com for details of our search terms for Medline and the Cochrane register (modified for OldMedline, Embase, and CINAHL). We applied no language restrictions. Study design filters included trials; cohort, case-control, and cross-over studies; and before and after and time series. We scanned the references of included studies to identify other potentially relevant studies.

We scanned the titles and abstracts of potentially relevant studies: when studies seemed to meet our eligibility criteria (or when information was insufficient to exclude them), we obtained the full text articles. We used a standardised form to assess the eligibility of each study, on the basis of the full article.

Quality assessment
We analysed randomised and non-randomised studies separately. Randomised studies were assessed according to the effectiveness of the randomisation method, the generation of the allocation sequence, allocation concealment, blinding, and follow-up. Non-randomised studies were assessed for the presence of potential confounders using the appropriate Newcastle-Ottawa Scales19 for case-control and cohort studies, and a three point checklist was used for controlled before and after studies.20

Using quality at the analysis stage as a means of interpretation of the results we assigned risk of bias categories on the basis of the number of items judged inadequate in each study: low risk of bias, up to one inadequate item; medium risk of bias, up to three inadequate items; and high risk of bias, more than three inadequate items.

Data extraction
Two authors (TJ, CDM) independently applied inclusion criteria to all identified and retrieved articles. Four authors (TJ, EF, BH, AP) extracted data from included studies and checked their accuracy on standard field forms used by Cochrane groups for vaccines, supervised and arbitrated by CDM.

Aggregation of data depended on study design; types of comparisons; sensitivity; and homogeneity of definitions of exposure, populations, and outcomes used. We calculated the statistic I2 for each pooled estimate to assess the impact on heterogeneity.21 22

When possible we did a quantitative analysis and summarised effectiveness as an odds ratio with 95% confidence intervals, expressing absolute intervention effectiveness when significant as a percentage using the formula: intervention effectiveness=1–odds ratio. For studies that could not be pooled we used effect measures reported by the authors (such as relative risk or incidence rate ratio, with 95% confidence intervals or, when not available, relevant P values). We calculated numbers needed to treat (NNT) using the formula 1/absolute risk reduction whenever we thought the data were robust enough to allow it.

Overall, 2300 titles of reports of potentially relevant studies were identified and screened. In total, 2162 were excluded and 138 full papers retrieved, totalling 49 reports of 51 studies (fig 1Go).

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