Swine flu update

Swine flu update

Swine flu has killed 95 people in north India since 1^st January.

1.       Swine flu causes fewer deaths than the routine seasonal flu.

2.      The Hong Kong Study of H1N1 (Between April and December 2009)

• Overall attack rate 10.7 percent.
• Case-hospitalization rate 0.47 to 0.87 percent among people aged 5 to 59 years.
• Case-ICU rate 7.9 cases per 100,000 infections in children aged 5 to 14 years.
• Case-ICU rate 75 cases per 100,000 infections in adults aged 50 and 59 years.
• Case-fatality rate 0.4 cases per 100,000 in children aged 5 to 14 years.
• Case-fatality rate 26.5 cases per 100,000 in adults aged 50 to 59 years.

3.   Case fatality is 0.4 – 26.5 cases per 100,000. This means 10 deaths would occur if one lakh people get the flu. To have 95 deaths, almost one crore people need to be infected. This again means 10% of the society suffering from flu or two patients per family. Either the figure 95 is wrong or the number of positive cases is incorrect.

4.   From 1^st Jan to 7^th Feb (flu season), in 38 days, 95 deaths means 2.5 deaths per day in flu season.  According to the Economy Survey of Delhi, a total of 868 people died of pneumonia in 2006 (year average per day 2.4) and 879 in 2007 (year average per day 2.4). This statistics is pre H1N1 era and will be true for seasonal flu.

5. 2.4 deaths in a year should mean that in the flu season the deaths would be many more. This proves the medical fact that swine flu cause fewer deaths than the seasonal flu. Then why panic?

6. US data

• 0.3 percent of cases require admissions in theUnited States.
• The mortality rate of 2009 to 2010 pandemic H1N1 influenza A infection was 0.12 deaths per 100,000 population.
• The mortality is high in severe cases admitted to the ICU: In California, 31 percent of patients were admitted to the intensive care unit and 11 percent died of pneumonia and dehydration.
• Only inMexico, the mortality burden was 0.6 to 2.6 times that of a typical influenza season but lower than that of the severe epidemic in 2003-2004.
• Two-thirds of deaths occur in people with underlying chronic illness.

7.     Severity over time: During the second wave of influenza activity of the pandemic, which peaked in late October 2009 in the United States, there were higher rates of pediatric mortality and higher rates of hospitalization in children and young adults compared with previous influenza seasons. No change in severity was observed among hospitalized children and adults with pandemic H1N1 influenza A in the United States in the fall of 2009 compared with the spring of 2010. We do not expect this year’s H1Ni flu to be more severe.

8.      Age: High rates of morbidity and mortality were noted among children and young adults across the globe. In some regions, older adults also had high rates of morbidity and mortality.

9.      The highest mortality was seen in Mexico. From this trend, the case mortality will be higher in India because of overcrowding.

10.  In seasonal flu, deaths occur more in people above 65 years of age and in H1N1 flu, deaths are more in 50-64 years age group.