Health District Urges Second Dose of Vaccine Upon Eligibility

New CDC Guidance Expands Time Window for Second Dose

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CORPUS CHRISTI, TX. - The City - County Public Health Department wants all those who have received the first dose of the Moderna vaccine to make getting their second dose on time a top priority. Waiting until the end of the CDC’s newly released six-week time frame for the second dose is not advised, as vaccines may not be available. The Health District advises planning to get the required second dose of vaccine on time based on the original schedule – three weeks for the Pfizer vaccine, four weeks for the Moderna vaccine. All vaccines administered at the mega drive thru clinic at the Richard M. Borchard Regional Fairgrounds to date have been the Moderna vaccine.

“Our concern is not that a second dose on the last day of the six-week interval isn’t safe and effective, our concern is that we can’t guarantee availability on that day,” said Annette Rodriguez, M.P.H., Director of Public Health. “If you wait until the end of the six-week period, there may be no vaccine on hand at that time to deliver a second dose. The sooner you attempt to get it, the sooner it can be done within the window.”

The CDC recently released guidance ( stating the second dose of vaccine can be safe and effective if administered up to six weeks after the first dose. While this expanded window of opportunity provides a longer time frame and helps address the issue of unpredictable vaccine supplies, those who have received the first dose should get their second dose as soon as they are eligible. Do not delay getting your dose when supplies are available.

The new six-week window is a MAXIMUM interval, not a minimum interval. The recommended time intervals between the first and second vaccine doses are:

  • Pfizer-BioNTech (30 µg, 0.3 ml each): 3 weeks (21 days) apart
  • Moderna (100 µg, 0.5 ml): 1 month (28 days) apart

“Based on the enthusiastic response, we anticipate that most of those who have received their first dose need no encouragement to get their second dose as soon as possible,” said Rodriguez. “But we also know that some will interpret the guidance as a six-week minimum delay or will simply put off getting their second dose as a matter of convenience. Make it a priority to get it as soon as you are eligible.”