Vaccination Second Dose Information

If you received your first dose at one of the Waco-McLennan County Public Health District Vaccine Clinics, you will be contacted to receive your second dose from there as well. 

When are my second doses needed?

People who receive the Pfizer-BioNTech vaccine should get their second dose 21 days after the first ones. A follow-up Moderna vaccine should be administered 28 days after the initial dose.

According to the Centers for Disease Control and Prevention, there is a four-day window when the second dose is considered valid, if someone were to get the vaccine early.

The second dose of the Pfizer-BioNTech is still valid on day 17 after the first injection, and the second dose of the Moderna vaccine is still valid on day 24 after the first injection.

The second doses need to be from the same manufacturer as the first ones.

What if someone can’t get a second dose on time?

Patients should plan to get their second doses as close to the recommended time as possible. If it’s not possible to do so, people can receive their second doses up to six weeks after the first, according to the CDC.

The CDC said that there is limited data for the effectiveness of the vaccines beyond the six-week interval but that the series of either vaccine does not need to be restarted if patients get their second doses more than six weeks after the first.

Do people have to go to the same providers for both shots?

State health officials recommend that people return to the same providers who administered their first doses.

If patients can’t get an appointment with their original providers, they can try registering with a vaccine hub if the hub accepts people who didn’t get their first shots there, or try contacting providers on the state’s availability map.

Why is a second shot needed?

Vaccines are intended to hardwire immunological memory to generate a rapid, targeted and durable response by antibodies and T-cells to an invading virus. Typically booster shots are intended to provide the immune system with advanced “training” to make better antibodies.

Some vaccines requiring multiple doses are administered four months apart to optimize immune memory. COVID-19 vaccines may work the same way, but it will take additional studies to know this for sure. Some companies are studying a single-shot COVID-19 vaccines, with results expected to be analyzed soon.