Single-dose swine flu vaccine in the works

A single-dose H1N1 swine flu vaccine may soon happen. Contrary to what was earlier expected, the vaccine against H1N1 may not be multi-dose, as results from a pilot study of Novartis H1N1 candidate vaccine revealed a strong immune response after just one shot. The vaccine might be used in trials in India as well.

Scientists from the University of Leicester, who tested the vaccine on 100 healthy volunteers aged between 18 and 50, found that more than 80% of the volunteers showed a strong, potentially protective immune response after one dose, with more than 90% showing the same response after two doses.

Trial leader Dr Iain Stephenson said, "The clinical trial of Novartis MF59-adjuvanted cell-based H1N1 vaccine indicates that the swine flu vaccine elicits a strong immune response and is well-tolerated. The results showed that the serum antibody responses were highest among subjects who received two doses of vaccine. However, a single vaccine may be sufficient to protect against H1N1."

The trails have a significance for India as it is one of the vaccines being eyed by India to be given to healthcare and emergency workers around February next year.

Novartis, which is presently carrying out global trials of this vaccine in more than 6,000 adults and children, has written to director general of Indian Council of Medical Research

Dr V M Katoch agreeing to carry out a separate trial in India to prove the vaccine's safety and efficacy on the Indian population.

India has been categorical that any vaccine it imports would have to undergo safety and efficacy trials on the Indian population before being introduced in the country.

The fear is that the vaccine may behave differently in Indians in comparison to people of other nationalities and may cause serious side effects like paralysis, urticaria and toxic reactions.

Dr Katoch told TOI, "Novartis has agreed to supply us this vaccine and has asked us to conduct our own trials with it. It won't really be a largescale trial but a two-month bridge study on hundreds of healthy volunteers. We will not accept data from the trials conducted in foreign countries."

According to scientists from the University of Leicester, the trial findings showed that it is possible to induce protective antibody against H1N1 infection within two weeks of administration of a single low-dose adjuvanted vaccine. This trial evaluated the tolerability and immunogenicity of the vaccine, and tested different schedules of vaccination, in terms of time between vaccinations.

Dr Stephenson said, "The aim of the trial was to find out how many doses and what type of vaccine is needed to give protection. These initial results should help to plan vaccination campaigns in the future. The research found the vaccine is well tolerated, with pain at the injection site the most frequent adverse event."

India plans to vaccinate 20 lakh healthcare and emergency services personnel against the deadly H1N1 virus by the end of January to start with, using an imported swine flu vaccine.

The health ministry has set aside Rs 100 crore as an interim budget to purchase these vaccines from any one the four international manufacturers -- Novartis, GSK, Sanofi Pasteur and Baxter -- whose candidates are presently undergoing human trials.

India expected the vaccine to be a double-dose vaccine and expected it to cost around Rs 500 per dose.

Interestingly, Dr Stephenson, before starting the trial had said it is almost certain two doses of vaccine will be needed. Unlike seasonal flu, where peoples bodies are partly primed to fight the virus as swine flu is a new infection none of us has met before. That’s why our body would need a priming dose and then a boosting dose. The vaccinations during the trails are being given between one-three weeks apart.