CDC offers guidance on H1N1, seasonal flu vaccine timing

Oct 28, 2009 (CIDRAP News) – Some clinicians and public-heath workers are experiencing understandable confusion about the timing of doses for H1N1 and seasonal influenza vaccines, as well as other childhood vaccines, officials at the US Centers for Disease Control and Prevention (CDC) said today in a conference call for health professionals.

To clarify the potentially complex dosing schedules, Dr. Anthony Fiore and Dr. Bill Atkinson of the CDC offered this guidance:

Doses of H1N1 flu vaccine and of seasonal flu vaccine can be administered at the same time so long as both vaccines are not in the live attenuated aerosol (nasal spray) format. An injectable version of either vaccine may be given at the same time as an injectable, or a live attenuated, version of the other vaccine. Administering both vaccines in the same visit in the aerosol live attenuated form is not recommended, they said.

In addition, they said, the H1N1 and seasonal vaccines can be administered at the same time as most other childhood vaccines. Inactivated influenza vaccine of either variety can be administered either at the same visit as, or any time after, other inactivated vaccines such as pneumococcal vaccine, or other live-organism vaccines such as MMR. And live attenuated flu vaccine can be administered at the same time as, or at any interval after, an inactivated vaccine such as pneumococcal vaccine.

However, they said, the CDC has proposed some restrictions on administering the live attenuated flu vaccine at the same time as an injectable live-organism vaccine: They should be administered either on the same day, or 4 weeks apart.

The officials said there have also been questions regarding the timing of successive doses of the H1N1 vaccine, which requires two doses in order to establish full immunity in children from the ages of 6 months through 9 years. As approved, they said, the two doses of H1N1 vaccine of either type should be separated by 4 weeks. If that is not possible, they said, then the two doses of live attenuated aerosol vaccine should be given at least 14 days apart, and two doses of injectable vaccine should be given at least 21 days apart.

Because the H1N1 vaccine is in short supply, health authorities have worked out prioritizations within the high-risk groups for whom the vaccine was first recommended. Those original priority groups are: pregnant women; children and young people from 6 months through 24 years old; household contacts and caregivers of children younger than 6 months; healthcare workers and emergency medical services personnel; and people between the ages of 25 and 64 years who have chronic medical conditions.

Where vaccine is limited, Fiore said, jurisdictions are refining those categories to focus first on children younger than 4 years or with chronic medical conditions, as well as on contacts of children younger than 6 months. But he urged call participants not to hold back if children within those narrow ranges do not come to vaccination clinics, but to use the vaccine for older children who might be present instead. "Don't let vaccine sit," he said, noting that many more doses are slated for delivery in coming weeks.

See also:

CDC Clinician Outreach and Communication Activity, "Children and H1N1 Influenza—H1N1 Vaccination and Treatment Information for Nurses, PA's and other Healthcare Professionals," Oct. 28

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