Pandemic Influenza: July 2006
Pandemic Influenza: July 2006
Ferguson NM, Cummings DA, Fraser C, Cajka JC, Cooley PC, Burke DS. Strategies for mitigating an influenza pandemic. Nature. 2006 Apr 26; Epub ahead of print. This is a follow-up report by experts in epidemic modeling to deal with global public health priorities in the event of pandemic influenza. Here the authors examine 4 issues in prevention models:
Internal or border travel restrictions: This and other analyses are based on data for the United States and Great Britain. The results show that border control to restrict passage by 90%, 99%, or 99.9% of people might delay the peak of a US pandemic by 1.5, 3, or 6 weeks, respectively. Their analysis also showed that eliminating travel in and out of the affected areas would delay the spread by up to 2 weeks. Closing airports for domestic travel had minimal impact.
Treatment of cases: The analysis showed that this would be effective in curtailing the epidemic only if there was very rapid treatment, meaning "same day treatment" of 90% of cases. This would reduce the attack rate from 34% to 29% and peak attack rate from 1.9% to 1.6%, assuming an antiviral stockpile sufficient for 25% of the population was available. The urge for early therapy was based on the fact that transmission is at a peak soon after symptoms develop. The investigators also note that effectiveness of antiviral treatment is based on the assumption that there would not be drug-resistant strains with efficient transmissibility similar to that of wild-type virus. They point out that such strains have not been reported to date.
Social distancing: Isolation such as school closings during the peak of the epidemic could reduce the peak attack rate by up to 40%, but this has little impact on the overall attack rate. However, case isolation or household quarantine could have substantial impact. Antiviral prophylaxis to household contacts would reduce the cumulative attack rates, but this would require a stockpile of antivirals sufficient to treat 46% to 57% of the population, which was considered unlikely.
Vaccine: Evaluations were based on the assumption that a single dose would give 70% protection. Vaccination at a rate of 1% of the population/day would need to begin 2 months before the pandemic outbreak to have a substantial impact. A delay of 4 months from the start of the pandemic would mean that the vaccine was available when the pandemic was over.
The authors conclude by noting the limitation of their data, which would be quite different if the modeling was based on the 1968 or 1957 pandemic rather than the 1918 pandemic.
Comment: It should be noted that this is the team that provided one of the initial strategies that received substantial attention, including adoption of many of the recommendations by the World Health Organization (WHO). This report seems rather depressing in terms of strategies that are likely to be effective, because we have all wanted the "quick fix." Nevertheless, it is somewhat reassuring that the avian influenza spread has slowed in both people and poultry.
Mounier-Jack S, Coker RJ. How prepared is Europe for pandemic influenza: analysis of national plans? Lancet. 2006;367:1405-1411. The authors surveyed the National Pandemic Influenza plans for 25 European Union countries, Bulgaria, Romania, Norway, and Switzerland using the WHO checklist for influenza epidemic preparedness. The results were based on 21 national plans that were eligible by inclusion criteria; these represented 93% of the population reviewed.
The highest scores were for France, Germany, Ireland, The Netherlands, Sweden, Switzerland, and the United Kingdom. Review of the plans indicated that attack rates were estimated at 15% to 50%, anticipated mortality was usually estimated at 230 to 465/100,000, hospital admissions were projected at 40 to 2770/100,000, the coordinating body was always the Ministry of Health, and the most common legal issues included were: quarantine, compulsory vs voluntary vaccination, and liability for adverse reactions related to the vaccine.
Public health issues included surveillance plans, availability of an in-country lab, restricted travel, public gatherings, and school closures and quarantine. Most of the plans addressed these issues; in each of the designated categories among the 21 plans reviewed, at least 15 of the plans addressed the individual public health issue.
For medical management, antivirals were recommended by all plans for treatment and by 18/21 plans for prophylaxis. In the majority of the plans, healthcare workers were the highest priority for both antivirals and vaccine administration. A summary of these plans is provided in the Table .
Conclusions: The authors conclude that there is "strong" governmental commitment in most European countries for pandemic influenza preparedness.
Comment: The data reviewed appear to show that Europe is substantially ahead of the United States in virtually every category. In large part, this is related to the fact that in the United States, much of the planning reviewed is relegated to states and major metropolitan areas. Problems are that response has been slow and poorly funded at this level. Further, in Europe, the great majority of healthcare is managed by national plans that have ownership and control. By contrast, the US system of healthcare is largely private, independent, financially distressed, and poorly coordinated for any integrated response to a healthcare crisis.
Ferguson NM, Cummings DA, Fraser C, Cajka JC, Cooley PC, Burke DS. Strategies for mitigating an influenza pandemic. Nature. 2006 Apr 26; Epub ahead of print. This is a follow-up report by experts in epidemic modeling to deal with global public health priorities in the event of pandemic influenza. Here the authors examine 4 issues in prevention models:
Internal or border travel restrictions: This and other analyses are based on data for the United States and Great Britain. The results show that border control to restrict passage by 90%, 99%, or 99.9% of people might delay the peak of a US pandemic by 1.5, 3, or 6 weeks, respectively. Their analysis also showed that eliminating travel in and out of the affected areas would delay the spread by up to 2 weeks. Closing airports for domestic travel had minimal impact.
Treatment of cases: The analysis showed that this would be effective in curtailing the epidemic only if there was very rapid treatment, meaning "same day treatment" of 90% of cases. This would reduce the attack rate from 34% to 29% and peak attack rate from 1.9% to 1.6%, assuming an antiviral stockpile sufficient for 25% of the population was available. The urge for early therapy was based on the fact that transmission is at a peak soon after symptoms develop. The investigators also note that effectiveness of antiviral treatment is based on the assumption that there would not be drug-resistant strains with efficient transmissibility similar to that of wild-type virus. They point out that such strains have not been reported to date.
Social distancing: Isolation such as school closings during the peak of the epidemic could reduce the peak attack rate by up to 40%, but this has little impact on the overall attack rate. However, case isolation or household quarantine could have substantial impact. Antiviral prophylaxis to household contacts would reduce the cumulative attack rates, but this would require a stockpile of antivirals sufficient to treat 46% to 57% of the population, which was considered unlikely.
Vaccine: Evaluations were based on the assumption that a single dose would give 70% protection. Vaccination at a rate of 1% of the population/day would need to begin 2 months before the pandemic outbreak to have a substantial impact. A delay of 4 months from the start of the pandemic would mean that the vaccine was available when the pandemic was over.
The authors conclude by noting the limitation of their data, which would be quite different if the modeling was based on the 1968 or 1957 pandemic rather than the 1918 pandemic.
Comment: It should be noted that this is the team that provided one of the initial strategies that received substantial attention, including adoption of many of the recommendations by the World Health Organization (WHO). This report seems rather depressing in terms of strategies that are likely to be effective, because we have all wanted the "quick fix." Nevertheless, it is somewhat reassuring that the avian influenza spread has slowed in both people and poultry.
Mounier-Jack S, Coker RJ. How prepared is Europe for pandemic influenza: analysis of national plans? Lancet. 2006;367:1405-1411. The authors surveyed the National Pandemic Influenza plans for 25 European Union countries, Bulgaria, Romania, Norway, and Switzerland using the WHO checklist for influenza epidemic preparedness. The results were based on 21 national plans that were eligible by inclusion criteria; these represented 93% of the population reviewed.
The highest scores were for France, Germany, Ireland, The Netherlands, Sweden, Switzerland, and the United Kingdom. Review of the plans indicated that attack rates were estimated at 15% to 50%, anticipated mortality was usually estimated at 230 to 465/100,000, hospital admissions were projected at 40 to 2770/100,000, the coordinating body was always the Ministry of Health, and the most common legal issues included were: quarantine, compulsory vs voluntary vaccination, and liability for adverse reactions related to the vaccine.
Public health issues included surveillance plans, availability of an in-country lab, restricted travel, public gatherings, and school closures and quarantine. Most of the plans addressed these issues; in each of the designated categories among the 21 plans reviewed, at least 15 of the plans addressed the individual public health issue.
For medical management, antivirals were recommended by all plans for treatment and by 18/21 plans for prophylaxis. In the majority of the plans, healthcare workers were the highest priority for both antivirals and vaccine administration. A summary of these plans is provided in the Table .
Conclusions: The authors conclude that there is "strong" governmental commitment in most European countries for pandemic influenza preparedness.
Comment: The data reviewed appear to show that Europe is substantially ahead of the United States in virtually every category. In large part, this is related to the fact that in the United States, much of the planning reviewed is relegated to states and major metropolitan areas. Problems are that response has been slow and poorly funded at this level. Further, in Europe, the great majority of healthcare is managed by national plans that have ownership and control. By contrast, the US system of healthcare is largely private, independent, financially distressed, and poorly coordinated for any integrated response to a healthcare crisis.
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