Tag: revaccination

Can I Get a Second Flu Shot for Extra Protection?

If one flu shot is good, wouldn’t two be better?

Can I Get a Second Flu Shot for Extra Protection?

Some people do get a second flu shot.

In fact, all kids eight years and younger, if it is their first time getting a flu vaccine, get two doses of flu vaccine.

How many doses of flu vaccine will your kids need this year?
How many doses of flu vaccine will your kids need this year?

The first dose is a priming dose and the second, at least 28 days later, is a booster dose.

Why do we do it that way?

Because studies have shown that is the best way to do it.

We don’t need to use this same priming/booster strategy in older children and adults though.

But with recent talk that protection against the flu after a flu vaccine might wane before the end of a flu season, some folks are likely wondering if they should just get another flu shot later in the season.

“Revaccination later in the season of persons who have already been fully vaccinated is not recommended.”

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices—United States, 2018–19 Influenza Season

And the official answer is no, except for younger children getting vaccinated for the first time, you should just get one dose per season.

Why not?

Mostly because a lot of studies haven’t been done to see what effect that second dose will have. And since some studies have even suggested that regular annual flu vaccines could actually lower vaccine effectiveness, you would want to know if getting an extra flu vaccine was safe and effective before we started to do it.

Not surprisingly, someone has looked into this already. One small study, Influenza revaccination of elderly travelers: antibody response to single influenza vaccination and revaccination at 12 weeks, actually showed that a second dose in the same season “did not enhance the immune response.”

So just one flu vaccine per season.

“Prior-season vaccination history was not associated with reduced vaccine effectiveness in children, supporting current recommendations for annual influenza vaccination of children.”

McLean et al on Association of Prior Vaccination With Influenza Vaccine Effectiveness in Children Receiving Live Attenuated or Inactivated Vaccine

But do get a flu vaccine every season.

Again, while there were some reports that an annual flu vaccine could lower vaccine effectiveness, other studies have disproven this.

More on Getting a Second Flu Shot

Vaccines After Cancer and Chemotherapy

Most people know that children being treated for cancer have a suppressed immune system and are at extra risk for vaccine-preventable diseases.

Many children with cancer and other medical conditions benefit from herd immunity.
Many children with cancer and other medical conditions benefit from herd immunity. (CC BY 2.0)

That’s one of the reasons that it is important for everyone to be vaccinated, so that herd immunity levels of protection can protect those who can’t get vaccines.

Vaccines After Cancer and Chemotherapy

But what happens after they complete their cancer treatments?

“The interval until immune reconstitution varies with the intensity and type of immunosuppressive therapy, radiation therapy, underlying disease, and other factors. Therefore, often it is not possible to make a definitive recommendation for an interval after cessation of immunosuppressive therapy when inactivated vaccines can be administered effectively or when live-virus vaccines can be administered safely and effectively.”

Red Book on Immunization in Immunocompromised Children

After they complete therapy for cancer, whether it is chemotherapy or a bone marrow transplant, many children need to get extra vaccines.

In the UK, for example, 6 months after completing “standard antileukemia chemotherapy,” children get a booster dose of DTaP, IPV, Hib, MenC, and MMR.

Why just a single booster dose?

Because most kids can continue to get non-live vaccines on schedule while they are getting standard chemotherapy. They get a booster dose when they finish chemotherapy because those vaccine doses they got while receiving treatment might not be as effective as usual and typically don’t count as valid doses.

Of course, if they were missing any doses, then they might need extra doses to catch up too.

“Three months after cancer chemotherapy, patients should be vaccinated with inactivated vaccines and the live vaccines for varicella; measles, mumps, and rubella; and measles, mumps, and rubella-varicella according to the CDC annual schedule that is routinely indicated for immunocompetent persons.”

2013 IDSA Clinical Practice Guideline for Vaccination of the Immunocompromised Host

In contrast to those getting standard chemotherapy, if treatment involved a hematopoietic stem cell transplant (HSCT), then these children are essentially revaccinated:

  • beginning at 6 months after the HSCT, they should get 3 doses of DTaP if they are less than 7-years-old vs a dose of Tdap and 2 doses of Td if they are already 7-years-old
  • beginning at 3-6 months after the HSCT, they should get 3 doses of Prevnar
  • beginning at 6-12 months after the HSCT, they should get 3 doses of Hib
  • beginning at 6-12 months after the HSCT, they should get 3 doses of hepatitis B, followed by postvaccination anti-HBs titer testing
  • beginning at 6-12 months after the HSCT, they should get 3 doses of IPV
  • beginning at 6-12 months after the HSCT, they should get 2 doses of a meningocococcal vaccine (if they are already 11 to 18 years old)
  • beginning at 6-12 months after the HSCT, they should get 3 doses of  HPV vaccine (if they are already 11 to 26 years old)
  • beginning at 12 months after the HSCT, one dose of the Pneumovax vaccine
  • beginning at 24 months after the HSCT, two doses of MMR
  • beginning at 24 months after the HSCT, two doses of the chicken pox vaccine
  • a yearly flu shot

Why not just check titers instead of repeating all of those vaccines?

“protective” concentrations or titers in this population may not be as valid as in healthy children, leaving open the question regarding what levels to use as the basis for revaccination. Furthermore, there are some vaccines for which no serological correlate of protection exists (e.g., pertussis) or for which, in routine practice, it is too difficult to have levels measured (e.g., polio).

Soonie R. Patel et al. on Revaccination of Children after Completion of Standard Chemotherapy for Acute Leukemia

In Canada, they used to check titers at 1, 3, and 5 years after the end of chemotherapy and just vaccinate when titers dropped, but they switched to giving all kids a booster dose, as it works better.

What will your child’s immunization look like after completing treatment for cancer?

Although the specific recommendations will come from your child’s treatment team, they will likely look something like the guidelines included here.

What to Know About Vaccines After Cancer and Chemotherapy

Kids often have to get revaccinated, or at least get booster doses of their vaccines, after completing treatment for cancer.

More on Vaccines After Cancer and Chemotherapy