Editorial, J Pharm Sci Emerg Drugs Vol: 9 Issue: 12
Physical interventions to interrupt or reduce the spread of respiratory viruses: a systematic review
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, and with incidence rates as high as 50% during major epidemics worldwide, respiratory viruses strain health services, are responsible for excess deaths, and result in massive indirect costs owing to absenteeism from work and school. 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. A new avian influenza pandemic caused by the H5N1 virus strain threatens greater catastrophe. 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. A recent trial found hand washing 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. We did not include vaccines and antivirals because these have been reviewed. Discussion In this systematic review we found that physical barriers such as handwashing, wearing a mask, and isolation of potentially infected patients were effective in preventing the spread of respiratory virus infections. It is not surprising that methods of the included studies were at risk of bias as these types of interventions are difficult to blind, are often set up hurriedly in emergency situations, and funding is less secure than for profit making interventions. Hasty design of interventions to minimise public health emergencies, particularly the six included case-control studies, is understandable but not when no randomisation (not even of clusters) was done in the several unhurried cohort and before and after studies, despite randomisation leading to minimal disruption to service delivery. Inadequate reporting often made interpretation of before and after studies difficult. The settings of the studies, carried out over four decades, were heterogeneous, ranging from suburban schoolsw to military barracks, intensive care units, paediatric wards in industrialised countries, slums in developing countries,w1 and day care centres for children with special needs.w22 Few attempts were made to obtain socioeconomic diversity by, for example, involving several schools in the evaluations of one programme. We identified few studies from developing countries where the most burden lies and where cheap interventions are needed. Even in Israel, the decrease in acute respiratory tract infections subsequent to school closure may have been related to atypical features: the high proportion of children in the population (34%) and limited access to over the counter drugs, which together with the national universal comprehensive health insurance means that symptomatic treatment is generally prescribed by doctors. Compliance with interventions�??especially educational programmes�??was a problem for several studies, despite the importance of such low cost interventions. Routine long term implementation of some would be problematic�??particularly maintaining strict hygiene and barrier routines for long periods, probably only feasible in highly motivated environments such as hospitals without the threat of an epidemic. Global and highly resource intensive measures such as screening at entry ports and social distancing lacked proper evaluation. The handful of studies (mostly done during the SARS epidemic) did not allow us to reach any firm conclusions, although a recent analysis of historical and archival data from the influenza pandemic in the United States suggests an effect of social distancing measures such as school closures and bans on public gatherings. Nevertheless our systematic review of available research does provide some important insights. Perhaps the impressive effect of the hygienic measures aimed at younger children derives from their poor capability with personal hygiene. Simple public health measures seem to be highly effective at reducing the transmission of respiratory viruses, especially when they are part of a structured programme including instruction and education and when they are delivered together. Further large pragmatic trials are needed to evaluate the best combinations. In the meantime we recommend implementing the following interventions combined to reduce the transmission of respiratory viruses: frequent hand washing (with or without antiseptics), barrier measures (gloves, gowns, and masks), and isolation of people with suspected respiratory tract infections.
Abstract
idemics 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, and with incidence rates as high as 50% during major epidemics worldwide, respiratory viruses strain health services, are responsible for excess deaths, and result in massive indirect costs owing to absenteeism from work and school. 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. A new avian influenza pandemic caused by the H5N1 virus strain threatens greater catastrophe. 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. A recent trial found hand washing 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. We did not include vaccines and antivirals because these have been reviewed.
