The Health Department has lifted almost all of the restrictions on the H1N1 vaccine for the last weekend of a free citywide immunization program. New Yorkers four years old or older can get vaccinated against the virus on Saturday and Sunday. More than 37,000 people have taken advantage of the free shots. The clinics will be open from 9 a.m. to 6 p.m. on Saturday, and from 9 a.m. to 5 p.m. on Sunday.

For more information of vaccination locations, go to nyc.gov/flu.

According to the New York Times, health officials are reporting that a review of side effects from the H1N1 flu vaccine indicates that the vaccine is safe, with adverse effects no different from those of seasonal flu vaccines.

Dr. Thomas R. Frieden, director of the Centers for Disease Control and Prevention, noted that the results were still preliminary, because the vaccine for the H1N1 flu has been in widespread use for about only two months. Adverse effects might not show up until later, after many more people are vaccinated.