New estimates provide more accurate data for public health officials to track vaccine reach
May 13, 2021
  • county of san mateo joint information center

    Redwood City – New population estimates for San Mateo County will change some of the percentages on COVID-19 data dashboards while providing public health officials with more accurate data.

    The state of California recently issued new estimates for the county’s population. These estimates drop the number of residents from 780,273 to 774,990, or 5,283 fewer residents than prior estimates.

    While the change is not large (roughly a drop of 0.68 percent), it does impact several key dashboards used to track the percentage of residents who have received the COVID-19 vaccine. In short, the updated demographic estimates show the makeup of San Mateo County as slightly smaller and slightly older.

    The estimated number of residents age 65 and older increases from 129,975 to 155,155, and the number of residents 75 and older rises from 55,739 to 69,895.

    Based on these new estimates, the overall percentage of eligible San Mateo County residents who have been vaccinated will increase. The percentage of vaccinated residents 65+ and 75+ will go down.

    Similarly, with the demographic data estimates, County Health will also be able to provide improved estimates of vaccination rates for particular populations by race/ethnicity. These may be different from prior estimates and projections, since they are based on the new calculation.

    County Health’s Epidemiology Unit has vetted the new numbers and believe they will provide a sharper picture of the demographics of the community and the reach of the vaccine:

    With the 12-15 year old population now eligible to receive the Pfizer vaccine, more current denominator numbers are available for this age group.

    More accurate and detailed population estimates by race/ethnicity and gender, and for all age categories, will show the reach and the gaps in vaccination.

    Dashboards with demographic information will be using the most current denominator data available, in line with the state and other county health departments.

    These new population projections are neither better nor worse than prior projections but will standardize County Health’s approach with many neighboring counties and with the State of California, using the most up-to-date population estimates available.

    The new numbers are from an annual update of population and other demographic updates for counties across California from the state Department of Finance. These updates were made available to county health departments in late April. San Mateo County Health will implement these changes this week.

    County Health has been using population estimates from the American Community Survey, which is the data from the US Census Bureau. This location-specific data set informs County Health dashboards related to vaccine reach in cities, ZIP codes, and census tracts.

    The Department of Finance data is not location specific but a county-wide estimate of demographic factors, such as age, race/ethnicity, and gender.

    Since the two sets of data cannot be cross mapped, County Health dashboards showing information related to location will continue to rely on the data from the American Community Survey, while those presenting demographic information will be based on data from the California Department of Finance.

    The data dashboards can be found at

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