The number of confirmed swine flu cases continues to rise: 4,298 in the US, 2,446 in Mexico, and a total of 7,520 worldwide in 34 countries. Much of the increase is just because labs are working through the samples that had been sent to them previously, but recent news from New York shows that the H1N1 virus is still spreading. Yesterday, three schools in Queens announced week-long closures after several students reported flu-like symptoms or were absent (241 students at one school, 50+ at another, and 29 at a third). The assistant principal from one of the schools, who is confirmed as having swine flu, has been hospitalized and placed on a ventilator; he reportedly had underlying health problems.

The fourth US swine flu death has been reported – an Arizona woman with an underlying lung condition – and Mexico has confirmed 60 H1N1 deaths. Canada and Costa Rica have reported one death each, out of 449 and eight lab-confirmed cases, respectively.

This virus is still spreading, and measures like school closures are still necessary. So far in the US, it seems that the virus has been relatively mild – but that could change quickly as it evolves. Reducing opportunities for further transmission and evolution is key. Keep washing your hands, covering your cough, and reducing contact with others if you feel sick.

This morning, President Obama announced his choice to head the CDC: New York City health comissioner Dr. Thomas Freiden, who’s an infectious disease specialist. Acting CDC Director Dr. Richard Besser has been doing a great job responding to the swine flu outbreak, but it’s important to have long-term leadership in place to make decisions about how the agency will address pressing issues – including a possible swine-flu vaccine – in the coming months and years.