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In an effort to stretch the supply of Covid-19 vaccines, some have advocated for further spacing out the two doses required for some of the shots or, in the case of the Moderna vaccine, lowering the dosage given with each jab.

But Nancy Messonnier, the director of the Centers for Disease Control and Prevention’s National Center for Immunization and Respiratory Diseases, reiterated Tuesday that federal health authorities continue to stand behind the current recommendations about the timing and strength of the shots, which were proven to be protective in clinical trials. She added that regulators and officials would continue to review new data as it was released.


“We have to stick with what we know works,” she told STAT reporter Helen Branswell during a live virtual conversation. “This is the regimen that’s been carefully studied. We’ve promised the American public that we would follow the data and follow the science, and that’s what we’re doing.”

So far, U.S. regulators have authorized three Covid-19 vaccines, a one-shot immunization from Johnson & Johnson and two-dose regimens from Moderna and Pfizer-BioNTech. The interval between Moderna doses is 28 days; for the Pfizer shot, it’s 21 days.

Some lawmakers and scientists have called for extending that period to get more people an initial dose, a step that some other countries have pursued. They’ve also called for looking into giving a lower dosage of the Moderna vaccine, which, as given now, contains about three times as much vaccine as the Pfizer shot. The U.S.’s vaccine development program has asked Moderna to study if the dosage could be reduced without pinching the amount of protection it confers.


But without additional data, Messonnier cautioned against such a move. She questioned whether lowering the dosage might have an effect on how long the vaccine guards people or reduce the quality of protection it provides.

“What folks have to understand is that there’s not just the efficacy today that we’re looking at,” she said. “We also want a vaccine that’s going to offer long duration of protection, because I frankly don’t want to have to do this more often than we need to, in terms of booster doses. We want a vaccine that not only protects the individual, but also protects the individual from transmitting.”

Messonnier also highlighted how, in the coming weeks, the vaccine supply in the country will increase, which will put greater pressure on immunization campaigns to reach people beyond those who are eagerly lining up for their shots. Some people remain hesitant about the vaccines, whereas others — including incarcerated people, people who are homebound, or people who don’t have internet access — will need special outreach to ensure access.

“This campaign has to be local,” she said. “In every local health department, and every local community, we need everybody to identify those populations and help us figure out how to access them.”

Branswell asked about plans to connect with young conservative men, a group that polling indicates are among the least likely to get immunized, but Messonnier answered generally, speaking about the need to reach out to community leaders and influencers no matter the demographic in question. She cited going to a vaccine clinic over the weekend that a pastor from a local Black church helped arrange.

Still, Messonnier acknowledged that health officials should have started their outreach and education efforts earlier last summer, “to really give people the time to grapple with what we were asking them to do in the winter.” She said that public health workers can help expand vaccine coverage by listening to people’s questions and by providing honest, forthright answers that specifically address how the questions were asked.

Messonnier, who has been vaccinated, described getting the shots as “an empowering choice” and that it was her goal to help people understand what a vaccine could do for them in terms of protecting them from Covid-19, but also protecting their families and communities.

“It’s an incredible feeling of relief to feel like, after such a long year and such a long winter, you actually have that measure of protection yourself,” she said. “I really hope everyone will understand that and want to feel that way.”

  • When the Chief Of Fear-Mongering, Fauci, took his B-12 shot in an arena of media blitz, my STEM hubby said “I assume he needed that B-12 shot”.
    Honestly, what about Enhanced Immune Response aka Pathogenic Priming, from these mRNA vaccines? What people don’t know might kill them when the wild virus hits them down the road. Just say’in…

  • EUA Emergency Use Authorization is not approval, for the COVID vaccines.
    The date it can be approved is 2023, and is still in trial.
    The public at large that takes these experimental vaccines are
    guinea pigs.
    What ever happen to the Nuremberg Codes?
    They seem to be using a lot of soft language, in “invitation” to vaccinate
    The CDC is a captured (follow the $) organization, along with the FDA, NIH, and our worthless govt. (Political Atheist, here)

  • Shocked to read this: “We also want a vaccine that’s going to offer long duration of protection”

    More than 1000 people are dying every single day, and she wants to think about the long term, because she doesn’t want to have to vaccinate everybody again? Despite the fact that we probably will have to vaccinate everybody again anyway, as the virus mutates? I will stop now before profanity ensues.

    • Why shocked that, all else held equal, the longer the protection the better? Everything in life has a cost consideration. If cost were no object there would not be hunger, homelessness and everyone would have the best medical care that current scientific advancement allows. I don’t understand your anger and frustration over what seems common sense.

  • As a researcher, I have had a look at the per reviewed paper that Pfeizer used to get approval. It looks very straight forward. around 20 000 are given the vaccine and the same number placebo. And surprisingly the placebo is saline.But there is a problem with the design.

    A general flu vaccine or fever medication could give the same results as the vaccine in this trial design.
    In principle if the Pfeizer vaccine just works on general flu or colds but not Covid, the results could be exactly the same, 90-95%. Only people with symptoms get tested, so if the vaccine reduces general flu or cold symptoms and there is a certain percentage of covid positive persons who are non symptomatic for Covid but have the flu, they would b counter as suffering from Covid.

    Flu symptoms that come after a jab could easily be counted by a motivated doctor as just vaccine side effects and not genuine Covid, and this person would not be tested. A motivated doctors who have guessed that a patient has got placebo will be very inclined to getting this person tested and counter as Covid.
    The more Covid patients you get in the Placebo group and the fewer you get in the Vaccine group, the better the result for Pfeizer.
    And a smart, motivated doctor could easily guess very accurately which group a patient belongs to.

    • Huh?
      “Per reviewed paper” what does that mean?

      Although seemingly not relevant to your argument, why is saline surprising?

      Then you lose a logical progression in saying the vaccine gives the same result as a flu medicine. Side effects aren’t the same as protection offered to a vaccine in fighting the virus it intends to fight.

      One of us is very confused.

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