Will I Need a Booster Shot If I Got the J&J Vaccine?

A bunch of COVID vaccine ampules neatly lined up on a blue background.

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Key Takeaways

  • Data release by Johnson & Johnson has shown that when a booster dose of the vaccine was given two months after the initial shot, it amplified antibodies 4-fold. When a booster dose was given six months after the first, it amplified the antibody levels 12-fold.
  • The Centers for Disease Control and Prevention recommend a booster of either mRNA COVID-19 vaccine (Pfizer or Moderna) for most people who received the Johnson & Johnson vaccine at least two months prior.
  • Moderately or severely immunocompromised persons who initially received the Johnson & Johnson vaccine should get an additional dose of either COVID-19 mRNA vaccine.

Johnson & Johnson is sharing new research on how long the protectiveness of its COVID-19 vaccine lasts. The findings come as many of the people who received the single-shot vaccine have started to wonder if they're still protected and if they need a booster shot.

Since it was the last COVID vaccine to be authorized for emergency use in the United States, J&J's six-month data on the shot's efficacy has only just appeared this week. The study was released pre-print (which means that it has yet to be peer-reviewed) on September 10.

The study looked at vaccine efficacy anywhere from 14 days after vaccination to 152 days after vaccination, finding no meaningful variation over that timespan. On average, the Johnson & Johnson vaccine appears to be 79% effective against COVID-19. But more research is needed on longer term effectiveness.

On September 21, J&J released a statement regarding the efficacy of its booster shots, which is part of the ongoing study on the vaccine's safety and efficacy.

Preliminary data show that when administered two months after the first shot, the J&J booster has a 94% efficacy rate against moderate to severe COVID infection and 100% efficacy against severe to critical infection. When the time between shots is longer, the booster may be even more effective; data showed a 12-fold increase in antibodies when the booster was administered six months after the first shot.

Do I Need a J&J Booster?

Many people who got the one-shot J&J vaccine—even those who do not have compromised immunity—are expecting to need a booster eventually. However, Sri Banerjee, MD,PhD, MPH, FACE, a faculty member at Walden University's PhD program in Public Health, tells Verywell that while booster shots are likely, they should not be assumed.

"Giving boosters to the immunocompromised is a no-brainer," Banerjee says. "But the caveat is that all the studies have measured is neutralizing antibodies. When it comes to other aspects of immunity, we have no clue what's going on there."

The ambiguity in the study results means that the Food and Drug Administration (FDA) has proceeded more cautiously than first expected when authorizing boosters. Banerjee says that from a public health standpoint, prioritizing unvaccinated people is still more important than boosters for the general population.

The Centers for Disease Control and Prevention (CDC) anticipates authorizing boosters for people who received the J&J shot, but it has not hinted at when that might happen. It took several weeks after Pfizer released its booster results for the shot to get authorization.

Since the J&J vaccine did not debut until 70 days after the Pfizer vaccine, it's unlikely that we'll see an authorization or approval before November, judging by approval timetables for other drugs.

Can I 'Mix and Match' COVID Shots?

For immunocompromised people, J&J's efficacy numbers may not be as reassuring as the efficacy rates demonstrated in the Pfizer or Moderna vaccine data. The Pfizer and Moderna vaccines offer higher initial efficacy rates around 95%, but the one-dose Johnson & Johnson vaccine still demonstrates a 79% efficacy against infections and an 81% effective rate against hospitalization.

The J&J shot uses more traditional double-stranded DNA to "teach" the immune system to recognize the COVID virus, while the Pfizer and Moderna vaccines use a newer mRNA method.

Even among people who do not have a compromised immune system, there has been a question of whether a "mix and match" booster strategy—giving one shot of either Pfizer or Moderna instead of an approved J&J shot—would be safe and effective.

For now, Banerjee says that accepted guidelines advise against the "mix and match" approach.

"You're trying to boost the effectiveness of the initial shot, so it should be with the original vaccine provided," says Banerjee, adding that, more importantly, there has been no hard data on the effects of mixing vaccines.

Some countries, including Israel and Germany, have started offering the option. In the U.S., the CDC will not authorize the practice without having data from peer-reviewed studies specific to mixing shots.

If you received the Johnson & Johnson COVID-19 vaccine, know that a recent study has suggested that the shot is maintaining efficacy over time.

With a booster shot, which will likely be approved in the coming months, the efficacy of the J&J shot will compete with the two-shot series by Pfizer and Moderna.

Currently, experts do not recommend "mixing and matching" COVID doses and are advising J&J shot recipients to be patient.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Polinski JM, Weckstein AR, Batech M, et al. Effectiveness of the single-dose ad26. Cov2. S covid vaccinemedRxiv. Published online September 16, 2021. doi:10.1101/2021.09.10.21263385

  2. Johnson & Johnson. Johnson & Johnson Announces Real-World Evidence and Phase 3 Data Confirming Strong and Long-Lasting Protection of Single-Shot COVID-19 Vaccine in the U.S.

By Rachel Murphy
Rachel Murphy is a Kansas City, MO, journalist with more than 10 years of experience.