Menactra is a conjugate vaccine that protects against four types of bacteria (serogroups A, C, W-135, and Y) that cause meningococcal disease, a serious infection of the brain and spinal cord lining or the bloodstream. It was one of the most widely used meningococcal vaccines in the United States for nearly two decades, though its manufacturer Sanofi Pasteur transitioned to a newer replacement vaccine in 2022.
What Menactra Protects Against
Meningococcal disease is caused by bacteria called Neisseria meningitidis. These bacteria come in several serogroups, and Menactra covers four of them: A, C, W-135, and Y. Together, these serogroups are responsible for a significant share of meningococcal infections worldwide. The disease can progress rapidly from flu-like symptoms to life-threatening meningitis or bloodstream infection within hours, which is why vaccination is so important.
Menactra does not cover serogroup B, which requires a separate vaccine. If you’ve heard of vaccines like Bexsero or Trumenba, those target serogroup B specifically.
How the Vaccine Works
Menactra is a conjugate vaccine, meaning it links pieces of the bacterial outer coating (polysaccharides) to a protein carrier. This pairing is what makes the vaccine effective across a wide age range, including young children whose immune systems don’t respond well to polysaccharides alone. The protein carrier essentially teaches the immune system to recognize and remember the bacterial coating, so it can mount a fast defense if you’re ever exposed to the real bacteria.
Conjugate vaccines also trigger a type of immune memory that polysaccharide-only vaccines cannot, which is why they provide longer-lasting protection and work in younger age groups.
Who Should Get It and When
Menactra was FDA-approved for people ages 9 months through 55 years. The dosing schedule depends on age:
- Children 9 through 23 months: Two doses, given three months apart.
- Individuals 2 through 55 years: A single dose.
The CDC’s routine recommendation focuses on adolescents. All 11- to 12-year-olds should receive a MenACWY vaccine, with a booster dose at age 16 because protection fades over time. That booster at 16 is timed so teens have strong immunity heading into their highest-risk years, particularly when they leave for college or military service, where close-quarters living increases exposure.
For children under 7 who are at ongoing higher risk (due to certain immune conditions or travel to areas with frequent outbreaks), the CDC recommends a booster 3 years after completing the primary series and then every 5 years after that.
How Effective It Is
Menactra’s effectiveness varies somewhat by age group and serogroup, based on the percentage of people who develop protective antibody levels after vaccination. In clinical studies reported by the CDC:
- Infants (two doses at 9 and 12 months): 89% to 96% developed protective levels against serogroup A, 98% or higher against C, 81% to 92% against W, and 95% to 97% against Y.
- Toddlers (two doses at 12 and 15 months): 85% reached protective levels against serogroup A, and 96% or more against C, W, and Y.
- Adolescents and adults (ages 10 to 55, single dose): 64% to 71% against serogroup A, 72% to 99% against C, 64% to 90% against W, and 39% to 82% against Y.
The wider ranges in adolescents and adults reflect variation across different study populations. Protection also wanes over time, which is exactly why the booster at age 16 is part of the routine schedule. Even when antibody levels decline, the immune system retains memory that can be reactivated by a booster dose.
Common Side Effects
Like most vaccines, Menactra’s side effects are typically mild and short-lived. The most common reactions include pain, redness, or swelling at the injection site. Systemic reactions like headache, fatigue, and mild fever are also reported, particularly in adolescents and adults. These generally resolve within a day or two.
One safety concern worth knowing about involves Guillain-Barré syndrome (GBS), a rare neurological condition. The CDC has noted a small number of GBS cases reported after Menactra vaccination, though a definitive causal link was never established. As a precaution, the CDC advises that people who have previously had GBS and are not at high risk for meningococcal disease should generally avoid the vaccine.
Menactra vs. MenQuadfi
If you’re searching for Menactra now, you may find it’s no longer available. Sanofi Pasteur transitioned to MenQuadfi as their sole meningococcal conjugate vaccine in 2022. MenQuadfi covers the same four serogroups (A, C, W, Y) and uses updated conjugate technology. It also has a broader approved age range, starting at 2 months old.
For practical purposes, if your child or teen is due for a meningococcal vaccine today, they’ll likely receive MenQuadfi or another currently available MenACWY vaccine like Menveo. These vaccines serve the same purpose as Menactra and follow the same CDC schedule. If your child previously received a first dose of Menactra, a different brand of MenACWY vaccine can be used for the booster.
Who Needs a MenACWY Vaccine Beyond Routine Schedules
Beyond the standard adolescent schedule, certain groups benefit from earlier or additional MenACWY vaccination. These include people with complement deficiencies or a missing or damaged spleen, since these conditions make it harder to fight off the bacteria. Microbiologists who work with meningococcal samples in the lab are also recommended to stay up to date. Travelers to the “meningitis belt” in sub-Saharan Africa, or anyone heading to the Hajj pilgrimage in Saudi Arabia, should be vaccinated before departure.
College freshmen living in dormitories who haven’t been vaccinated or boosted after age 16 are another priority group. Outbreaks on college campuses, while uncommon, do occur, and close living arrangements increase transmission risk significantly.