While the majority of people receiving either the Pfizer or Moderna COVID-19 vaccine are completing the full two-dose series, there are still some who aren’t showing up for their second-dose appointments.
But does it really matter?
“Yes, it matters. The second dose gives you more protection than you might think,” said Sandy Salverson, PharmD, vice president of Pharmacy Operations for OSF HealthCare. “Both the Centers for Disease Control and Prevention and the U.S. Food and Drug Administration would have approved just a single dose of Pfizer and Moderna if the vaccines provided enough immunity after a single dose. That’s just not the case. A single dose is not good enough.”
The difference in doses
The first dose, Sandy said, primes the immune system to recognize the virus that causes COVID-19.
“The second shot boosts your immunity, further providing you more protection from becoming seriously ill from the virus that causes COVID-19,” she said. “The second dose not only induces cellular immunity for longer protection, but it provides you with better protection against variant strains.”
The COVID-19 vaccines manufactured by Pfizer and Moderna aren’t the first vaccines requiring two doses. Several required childhood vaccines require two or more doses to provide the best protection against disease possible.
Is supply an issue?
Earlier in the vaccinations, supply may have been an issue for second doses. But that’s no longer the case, Sandy said.
“There is plenty of supply now,” she said. “When you get your first dose and if your second dose appointment isn’t automatically scheduled, ask for that appointment to be made and confirmed.”
And while it’s encouraged to get your second dose at the same location where you received the first, if that’s not possible, some of the national retail pharmacies can administer a second dose. Just make sure to take your vaccination card with you so you confirm you receive the same manufacturer – Pfizer or Moderna – that you did for the first dose.
Need a COVID-19 vaccination?
If you are traveling or just not available on the day your second shot is scheduled, get it as soon as possible.
“The timing of the second dose doesn’t need to be exact,” Sandy said. “If you have to miss your scheduled appointment for some reason, there is wiggle room to get the second dose, even though it is optimal to get your second Pfizer dose 21 days after your first and Moderna 28 days after the first.”
CDC guidelines state the second shot may be given up to six weeks (42 days) after the first dose, if necessary, but you should not get it earlier than 21 for Pfizer or 28 days for Moderna.
Concerns about side effects
Some people are skipping their second dose out of concerns they’ll have stronger side effects following the second dose than what they experienced with the first.
Experiencing side effects, Sandy said, is a normal reaction to a vaccine and is really very individualized. Everyone has their own story about what they experienced following their first and second dose shots.
“For many, the side effects like soreness where the shot is given, redness, minor swelling, are not any more noticeable between the first and second dose,” she said.
And it depends on if you had COVID-19.
“If someone had COVID-19 and received the vaccine, typically the side effects of fever, fatigue or headache could be more noticeable after the first dose,” Sandy said. “For people who did not have COVID-19, those same side effects may be more noticeable after the second dose.
“But remember, these side effects are typical with all vaccines. They begin within 12 hours of receiving the shot and often end within 24 hours,” she said.
Get the second dose
What it comes down to is that receiving only one dose of a two-dose COVID-19 vaccine is not as useful as receiving the full series. Given the spread of the virus and its variants and the serious health risk it poses, the second dose is strongly recommended.
When you’re fully vaccinated – 14 days from receiving the second dose of either Pfizer or Moderna or the one-dose vaccine from Johnson & Johnson – you’ll be able to start doing a lot of the activities you haven’t been able to do throughout the pandemic.
Last Updated: February 16, 2024