Are there human infections with novel H1N1 virus in India?
Yes. Human infections with the new H1N1 virus are ongoing in India. Most people who have become ill with this new virus have recovered without requiring medical treatment.

Ministry of Health & Family Welfare, Government of India is working closely with states to collect, compile and analyse information about novel H1N1influenza, since the beginning of the outbreak. Information is presented on a regular basis through press releases and on the ministry’s website.

Is novel H1N1 virus contagious?
Yes. Novel H1N1 virus is contagious and is spreading from human to human.

How does novel H1N1 virus spread?
Spread of novel H1N1 virus is thought to occur in the same way that seasonal flu spreads. Flu viruses are spread mainly from person to person through coughing or sneezing by people with influenza. Sometimes people may become infected by touching something – such as a surface or object – with flu viruses on it and then touching their mouth or nose.

What are the signs and symptoms of this virus in people?
The symptoms of novel H1N1 flu virus in people include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills and fatigue. A significant number of people who have been infected with this virus also have reported diarrhea and vomiting. Severe illnesses and death have occurred as a result of illness associated with this virus.

How severe is illness associated with novel H1N1 flu virus?
Illness with the new H1N1 virus has ranged from mild to severe. While most people who have been sick have recovered without needing medical treatment, hospitalisations and deaths from infection with this virus have occurred.

In seasonal flu, certain people are at “high risk” of serious complications. This includes people 65 years and older, children younger than five years old, pregnant women, and people of any age with certain chronic medical conditions.

Data on patient morbidity and mortality in India is still accumulating. However, global data suggests that about 70 percent of people who are hospitalised with this novel H1N1 virus have one or more medical conditions previously recognized as placing people at “high risk” of serious seasonal flu-related complications. This includes pregnancy, diabetes, heart disease, asthma, obesity and kidney disease.

One thing that appears to be different from seasonal influenza is that adults older than 64 years do not yet appear to be at increased risk of novel H1N1-related complications. Studies have shown that no children and very few adults younger than 60 years have existing antibody to novel H1N1 flu virus; however, about 1/3 of adults older than 60 may have antibodies against this virus. The level of protection that these existing antibodies can provide against novel H1N1 flu, is still unknown.

How does novel H1N1 flu compare to seasonal flu in terms of its severity and infection rates?
With seasonal flu, we know that seasons vary in terms of timing, duration and severity. Seasonal influenza can cause mild to severe illness, and at times can lead to death. According to WHO’s estimation, seasonal influenza epidemics result in about 3 million to 5 million cases of severe illness worldwide, and about 250 000 to 500 000 of the people with severe illness die each year from complications of influenza. Most of these complications and deaths occur in less than 5 year and more than 65 year-old patients

Since the time of emergence of novel H1N1 flu in mid-April 2009, WHO has been working with countries to collect, compile and analyse information regarding thel H1N1 outbreak, including numbers of confirmed and probable cases and ages of these people. The information analysed supports the following conclusions:

	Most cases of H1N1 infection have had mild typical influenza-like illness with fever, cough, runny nose, headache and malaise. Severe illness was reported in Mexico and United States, in persons who are at risk for complications of seasonal influenza, such as very young, women who are pregnant and persons with underlying medical conditions, as well as healthy young adults
	Factors associated with an increased risk of severe seasonal influenza such as pregnancy, chronic medical conditions, very young or very old age.
	The principal reason for hospitalisation of cases in Mexico and US has been severe respiratory disease. In the Mexican experience, secondary bacterial pneumonia has occurred among hospitalised cases. Data on underlying disease, if any, in death cases in India is being analysed. It appears that majority had underlying conditions as identified above
	Some confirmed cases did not have fever; it is likely there are asymptomatic and very mild cases of infection -- as occurs with seasonal epidemics of influenza
	Some, but not all, countries reported cases with diarrhea. This initial finding requires further confirmation, and studies to determine if virus is shed in the feces. If this is found, it could have significance for countries or situations in which there is inadequate sanitation
	While all age groups have been affected, most cases are occurring in younger age groups with a median age in the mid-20's. Similar pattern is emerging in India as well, though we still have to witness the detailed analysis.
	The virus appears to be easily transmitted from person to person. In US and Mexico, community transmission has been widespread. Based on limited data, the secondary attack rate is estimated to be about 22%t, but could be as high as 30% in some settings
	Mexico experienced a large number of persons over a short period of time seeking care and hospitalisation for respiratory disease. However, health care systems of other affected countries have not had a similar experience to date
	At present, the virus is generally susceptible to oseltamivir (Tamiflu) and zanamivir (Relenza) with sporadic reports of resistance to oseltamivir in few countries (Denmark, Japan and the Special Administrative Region of Hong Kong, China) based on laboratory testing. These sporadic viruses were found in three patients who did not have severe disease and all have recovered. Investigations have not found the resistant virus in the close contacts of these three people. At this time, there is no evidence to indicate the development of widespread antiviral resistance among pandemic H1N1 viruses
	In laboratory studies, there is no evidence so far that the virus has markers for human virulence that have been described for the 1918 H1N1 pandemic virus and avian influenza H5N1 viruses

1. Countries are using different surveillance methods and case definitions to detect cases; this will influence information about clinical disease. For example, case detection focused in hospitals would be expected to preferentially detect cases of H1N1 infection with more severe disease. Conversely, detection and investigation of cases in the community setting may favour finding less severe illness.

2. Most countries are at an early stage of disease spread and have reported a small number of cases. The experience of Mexico and US suggests that only as more cases occur and infection spreads into the wider community can a more complete picture of the epidemiological and clinical characteristics of the H1N1 virus begin to be delineated. Caution must be exercised in interpreting information such as age as it may reflect patterns of travel or the occurrence of outbreaks in special settings such as schools.

3. Early estimates of important epidemiological parameters such as incubation period and attack rate have been derived from a limited number of settings such as households and schools and may not be broadly generalisable.

4. Although Mexico and US reported deaths among persons with confirmed H1N1 infection, it is too early to get a reliable estimate of the case fatality ratio. Additional studies are needed to assess risk factors for infection with H1N1 virus and the severity of illness. The situation is expected to evolve over time and bears careful watching. Though illness to date has been mainly mild, as number of cases and geographic spread of the virus increase, a fuller picture will emerge that will likely include increased numbers of severe illness and deaths -- as occurs with influenza epidemics each year.

How long can an infected person spread this virus to others?
People infected with seasonal and novel H1N1 flu shed virus and may be able to infect others from 1 day before getting sick to 5 to 7 days after. This can be longer in some people, especially children and people with weakened immune systems and in people infected with the new H1N1 virus.