Second, both BRFSS and NHFS are telephone-based surveys and thus do not include persons without telephone service.
Additional information about NHFS is available at http://www.
section]) Combined estimates were weighted averages of the BRFSS and NHFS estimates, with weights being determined by the effective sample sizes.
For NHFS, the Council of American Survey and Research Organizations (CASRO) response rate for the weekly sample groups released through January were 35% for landline telephones and 27% for cellular telephones; cooperation rates were 45% and 57% for landline and cellular telephones, respectively.
As of the end of February, based on data from BRFSS and NHFS combined, the estimated coverage rate was 24.
Combining BRFSS and NHFS estimates increased the size of the sample to approximately 200,000 persons and increased precision of estimates but might also constitute a limitation in interpretation of the results.
First, BRFSS is a landline, telephone-based survey and thus excludes persons in households without landline telephones; NHFS includes households with landlines as well as those with only cellular telephone service; and both BRFSS and NHFS exclude households with no telephone service.
CDC will continue to analyze BRFSS and NHFS data to provide updated estimates of vaccine utilization and identify specific aspects of the 2009 H1N1 vaccination program that were successful and could be integrated to improve future season vaccination rates.
For both NHFS and BRFSS, respondents with missing influenza vaccination information were excluded.
From October 10, 2009 to January 2, 2010, the weekly NHFS percentage of U.
According to NHFS estimates, vaccination coverage was 27.
Among the December 27-January 2 NHFS participants who had not yet received 2009 H1N1 vaccination, 10.