Some 2,000 Israelis have been diagnosed with swine flu, the Health Ministry announced Sunday, 15 of whom are currently hospitalized in serious condition. However, the ministry estimated that the actual number of people infected with the H1N1 virus in Israel was much higher, due to carriers who have not yet been tested. Health Ministry Director-General Prof. Avi Yisraeli told Israel Radio on Sunday that thousands of Israelis have most probably contracted swine flu and mistaken it for regular flu. Such people would most likely have suffered mild symptoms such as "a bit of a fever, and slight shortness of breath," he said. Yisraeli also noted that children and young adults up to the age of 21 who had contracted the H1N1 virus tended to have symptoms very similar to the regular flu, and that people aged 60 and above were less likely to contract the H1N1 virus. The director-general reiterated previous advice to the public to "watch their hygiene as much as possible," by washing hands often, and staying home from work or school if ill. Also Sunday, Deputy Health Minister Ya'acov Litzman was set to leave for a US visit, part of which will be spent trying to get options on H1N1 flu vaccines from various companies. He reportedly wants US health officials to set aside some of the vaccines they are to receive for sale to Israel, with the aim of vaccinating high-risk groups. Prime Minister Binyamin Netanyahu is expected to ask German Chancellor Angela Merkel and British Prime Minister Gordon Brown for vaccine supplies as well. On Friday, a fifth Israeli died of H1N1 swine flu virus. The man, 50, who like the previous victims suffered from a chronic illness, died at the capital's Shaare Zedek Medical Center. On Friday afternoon, Litzman and senior ministry officials signed the ministry's first agreement with a pharmaceutical company that has produced an H1N1 vaccine, obtaining options for the purchase of NIS 7 million worth after it is tested, proven safe and approved by regulators. This represents only a small amount of vaccine; it would cost about NIS 450m. to purchase enough vaccine for the entire Israeli population. The agreement was signed with the French company Sanofi Pasteur, which has started human trials of its vaccine on some 2,000 healthy Americans. Besides testing for safety, the company also needs to conduct clinical trials to determine how many doses are required to protect those injected from swine flu. The pharmaceutical company, which products about two-fifths of the world's influenza vaccines, has applied to the US Food and Drug Administration for fast-track licensing for the vaccine. The World Health Organization said late last week that it will approve H1N1 flu vaccines for sale and use within a month. Magen David Adom said it is boosting its preparations for the possibility of an H1N1 epidemic here. It has purchased advanced masks and other protection equipment (including disinfection sprays for ambulances) for its staffers and volunteers, organized briefings for them and prepared a national MDA preparedness plan. Meanwhile, Dr. Bruria Ben-Ze'ev, head of the pediatric neurology department at Safra Children's Hospital at Sheba Medical Center in Tel Hashomer and director of the national Rett Syndrome clinic there, urged doctors and parents of Rett Syndrome children (most of them girls) to regard them as being at high risk for complications of swine flu. The 12-year-old girl who died last week of flu complications suffered from Rett Syndrome. When any flu symptoms appear in these children, they should quickly be prescribed the anti-viral drug Tamiflu, Ben-Ze'ev said.