A new strain of influenza virus responsible for 99.8% flu infections in the US now could be responsible for some of the deaths in the recent swine flu outbreak in India, says a visiting scientist and director of Atlanta Emory Vaccine Centre.

The H3N2 virus, is one of the three sub-types of swine flu but labs in India are only looking for H1N1 strains. H2N2 is the other strain.

Dr Rafi Ahmed, who is leading an inter-governmental vaccine development programme of the Emory Centre and New Delhi-based International Centre for Genetic Engineering and Biotechnology (ICGEB), called for studying the strains of the influenza virus in the current outbreak.

At least 20 deaths in Telangana could have been caused by other strains of swine flu, agree doctors.

With similar symptoms to H1N1 infected cases, these patients who were sent home after showing negative results for H1N1 died within a few days.

A panic-driven rush for vaccines at drug stores is sending the stocks low.

The trivalent influenza vaccine gives protection against H1N1, H3N2 and Influenza B. The vaccine takes at least two weeks to develop immunity and provides about 60-80% protection for about a year.

Following consultations with experts, the Indian government has recommended vaccination only for health workers.

Toll crosses 900

Meanwhile, the Indian Health Minister JP Nadda has urged the public not to panic, even as the number of deaths from swine flu crossed 900 in less than two months, while the number of infected cases stood at 16,000.

Almost 51 deaths were reported in a single day.

Most of the deaths have been from complications arising from other diseases or disorders present in the patient. Patients have been coming into hospitals very late, further aggravating their condition, said a statement issued by the ministry.

The drug oseltamivir remains effective for treatment, it said.

Virologists have recommending the use of N-95 face masks which filter out over 95% of small air droplets if worn correctly.

But the masks should not be worn for more than two hours and need to be disposed off carefully.

Washing hands thoroughly for a good two minutes using a soap solution has also been recommended as a way to reduce exposure risks.

Thirty five fresh swine flu cases have been reported in the state of Telangana on a single day.

According to the ministry, Rajasthan accounts for the highest number of deaths at 234, along with 4,884 infections. Gujarat ranks second at 231 deaths and 3,527 infections. Rise in infections has been seen in Delhi with 2571 cases.

Curfew in Ahmedabad

The Ahmedabad district collector invoked the Criminal Procedure Code's Section 144 on Tuesday, prohibiting mass gatherings without prior permission in a bid to check the spread of swine flu. Marriages and death processions have been exempted.

Madhya Pradesh, Maharashtra, Telangana, Karnataka and Punjab have reported some deaths too.

The World Health Organization has said it was "carefully watching" the swine flu situation in India while ruling out signs of a large outbreak as yet.

The outbreak is expected to subside as temperatures rise during the summer but will pick up when temperatures drop after the rains in July.