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Family Planning:
SOCIAL DISTANCING
An official look at a national plan for Social Distancing during an influenza
pandemic related to H5N1 avian and bird flu
Working on the basic principle that the influenza virus cannot be transmitted
unless there is contact between individuals, prevention measures need to be
focused on reducing close contact. This is called Social Distancing.
Here are the key issues and reasons for Social Distancing.
Social Distancing applies particularly to public gatherings and schools since these are situations in which the presence of large groups of people is especially conducive to the spread of influenza. Appropriate restrictions and bans on events should reduce the burden of disease by slowing its spread and flattening the pandemic wave (by reducing morbidity, mortality and the impact on the health service and by gaining time to develop a vaccine).
In short
Most countries will adopt a policy to prevent or ban public or private gatherings of more than 50 people who do not normally live, work or study together. This will include sports events, church meetings (weddings and funerals), public events and of course all school and university events.
Large gatherings of people, particularly in the context of public transport, shopping (apart from one-off trade fairs and exhibitions), the health service, the exercise of political rights and the armed forces, will be evaluated on a per-case basis. As each wave of a pandemic occurs, it is expected that public transport will cease including air travel, train travel and so on.
Past Pandemics
There is little scientific evidence that Social Distancing measures are an efficient way of slowing the spread of an influenza pandemic, and findings to date are very difficult to extrapolate to a future pandemic. Efforts were made during the three pandemics that occurred during the 20th century to stop the spread of influenza, but on the whole these proved to be not very effective. It is practically impossible to stop the spread of the infection once sustained human-to-human transmission has been established. However, non-medical measures seem to be efficient provided that they are initiated as early as possible and combined with other measures. The window of opportunity for preventing a pandemic or for appreciably slowing its spread lasts from Phase 4 to Phase 5. In Phase 6, Social Distancing attempts more to limit the damage caused by the pandemic (to reduce its extent) than to prevent the infection from spreading to new groups or zones.
Children
Children are particularly likely to fall victim to a flu epidemic or pandemic, and are particularly likely to spread the influenza virus, because of their behavior and certain biological factors. For this reason schools can play a major role in a pandemic, as was observed in the USA in 1918 and 1957. The same observation was made in the United Kingdom in 1957, although not during the 1968 pandemic. A pandemic wave can be of relatively short duration (four weeks) within a school, even if it is severely affected. During a pandemic, each wave can affect a different age group particularly severely. The age group most severely affected may also vary within a single wave; this has been observed during epidemics of seasonal flu, when school children were affected first, followed by preschoolers and finally adults.
Experience has shown that when schools are closed for or reopen after holidays, this affects the way influenza spreads during a pandemic. Individual reports indicate that outbreaks of pandemic and seasonal influenza can be contained by closing schools. Mathematical models show that closing schools reduces the total burden of the disease, particularly if they are closed at the start of an outbreak.
The efficiency of Social Distancing measures depends on a number of factors: their nature, the speed with which they can be implemented, how systematically they are employed, how well they are accepted by the population, the degree to which they are adapted to the new influenza virus subtype or pandemic virus, and prior experience. Social Distancing should only be considered in conjunction with a package of control measures in order to derive benefit from synergy effects.
Objectives
Remember, the object of any social distancing is to prevent a new influenza virus subtype or pandemic virus being brought into the country and to prevent or slow its spread in the population.
Assumptions About Social Distancing
− Once a pandemic wave reaches a country, it will take 2 to 3 weeks for the pandemic virus to spread throughout the country.
− The disease will be transmitted from human to human (at a distance of < 1 meter), mainly in droplets. Cramped, poorly ventilated rooms are conducive to virus transmission.
− The incubation period for influenza is 1 to 4 days (within 2 days).
− Individuals are contagious from approximately 1 day before until 7 days after the symptoms appear. The contagious phase lasts longer in children and immune-suppressed individuals: up to 21 days.
− There are presumably major differences between the seasonal influenza virus and a pandemic virus in terms of spread, distribution among age groups and the severity of the illness. These differences will not be quantifiable until human-to-human transmission begins. However, it is assumed that the attack rate among school-age children will be between 40 and 50%, i.e. considerably higher than the attack rate among adults (25%).
It is also assumed that:
- At no time will an international border be closed.
- It will be possible to halt the development of the situation in the inter-pandemic alert period (Phase 4 or 5), so there is no transition to the pandemic period. Once the pandemic stage has been reached, it will be practically impossible to prevent influenza from spreading.
- A pandemic vaccine will not be available during the first wave.
- Irrespective of the extent of the pandemic, essential government services will continue to operate.
- Organizers will be requested to withdraw voluntarily from holding international events.
- Depending on the epidemiological situation, the workload of the public administration and the prevailing mood (anxiety or uncertainty), authorities may issue a general ban on events for their region as a precautionary measure; however, provision may be made for exceptions. A measure of this kind should be decided in conjunction with the federal authorities or imposed on the entire country by the federal authority.
- Maximum efforts will be made to limit the new influenza virus subtype to the initial foci or to slow its spread, thus gaining time for control measures; these will comprise restricting or forbidding sick or potentially infected people from attending events and schools.
References
- Ferguson NM, Cummings DA, Cauchemez S, Fraser C, Riley S, Meeyai A, Iamsirithaworn S, Burke DS. Strategies for containing an emerging influenza pandemic in Southeast Asia. Nature 2005; 437: 209-14.
- Frost WH. The epidemiology of influenza. J Am Med Assoc 1919; 73: 313-8.
- Ghendon YZ, Kaira AN, Elshina GA. The effect of mass influenza immunization in children on the morbidity of the unvaccinated elderly. Epidemiol Infect 2005; 134: 1-8.
- Glezen WP. Serious morbidity and mortality associated with influenza
epidemics. Epidemiol Rev 1982; 4: 25-44.
Glezen WP. Emerging infections: pandemic influenza. Epidemiol Rev 1996; 18: 64-76. - Hall CB, Douglas RG Jr., Geiman JM, Meagher MP. Viral shedding patterns of children with influenza B infection. J Infect Dis 1979; 140: 610-3.
- Jordan WS Jr., Denny FW Jr., Badger GF, Curtiss C, Dingle JH, Osaasohn
R, Stevens DA. A study of illness in a group of Cleveland families. XVII.
The occurrence of Asian influenza. Am J Hyg 1958; 68: 190-212.
Jordan WS Jr. The mechanism of spread of Asian influenza. Am Rev Respir Dis 1961; 83(2) Pt 2: 29-40. - Longini IM Jr., Monto AS, Koopman JS. Statistical procedures for
estimating the community probability of illness in family studies:
rhinovirus and influenza. Int J Epidemiol 1984; 13: 99-106.
Longini IM Jr., Nizam A, Xu S, Ungchusak K, Hanshaoworakul W, Cummings DA, Halloran ME. Containing pandemic influenza at the source. Science 2005; 309: 1083-7. - National Health Service. Pandemic flu: UK influenza pandemic contingency plan. October 2005. 177 p.
- Semple AB, Davies JB, Disley PJ. Influenza in Liverpool. Lancet 1958; 1: 95-7.
- United States, Department of Health and Human Services. Pandemic influenza plan. November 2005. 396 p.
- Viboud C, Boelle PY, Cauchemez S, Lavenu A, Valleron AJ, Flahault A, Carrat F. Risk factors of influenza transmission in households. Br J Gen Pract 2004; 54: 684-9.
- Swiss Influenza Pandemic Plan 2006, page 57 of 190.
Poll Results: Our
Quick Poll for December asked, "Are we spending too much on bird
flu?"
Yes : 21.7%
No : 73.9%
Unsure : 4.3%
Some 800 people polled.
Next: » Case Study: How our community reacted to H5N1 when it came.
All Articles
in this series:
» Family Planning Practical steps (part 1)
» Family Planning Practical steps (part 2)
» Social Distancing and How the National Plan Will Effect
You
» Case Study: How our community reacted to H5N1 when it came.
» Specific advise for your children.
» Face masks, which ones work and when to change them,
details
Video Presentation:
(Requires free Google video software) (21 min)
Brent Woodworth, head of the IBM Crisis Response Team, explains in
this 21-minute presentation some of the critical aspects of preparing your
business to meet the threat of an avian influenza pandemic.
This presentation was made at the 2nd International Bird Flu Summit in
Washington, DC, held June 28-29, 2006.
(This
is a link to the Google Video site only - opens new window.)