• The U.S. Centers for Disease Control and Prevention (CDC) has approved a second COVID-19 booster shot of the Moderna or Pfizer messenger RNA (mRNA) vaccine for people over 50 years old and those who are immunocompromised.
• Recent studies found most people who were immunocompromised had a strong immune response to mRNA vaccines for COVID-19.
• With the omicron variant waning and COVID-19 control measures ending, now is an ideal time to get up to date on vaccinations before new variants arise.

The CDC and U.S. Food and Drug Administration (FDA) have authorized and recommended a second COVID-19 booster shot for all adults 50 and older and people with suppressed immune systems. Some people living with multiple sclerosis (MS) may be immunocompromised from taking certain disease-modifying therapies (DMTs). Immunocompromised people are at an increased risk for severe disease and hospitalization from COVID-19, so additional protection against infection is important.

These recommendations are based on research findings that receiving an initial booster of the Moderna or Pfizer vaccine is safe and effective in preventing severe disease and hospitalization. These vaccines both use mRNA to teach cells how to make a protein that will trigger an immune system response and help prevent a COVID-19 infection.

The CDC has also found that the effectiveness of the first booster decreases over time, so the organization is now recommending a second booster to help maintain protection against COVID-19 infection.

The New Recommendations and Second Booster Eligibility

On March 29, the FDA authorized a second booster for the following groups:

• Individuals aged 50 or older who received a first booster dose of the Pfizer or Moderna vaccine are eligible to receive a second booster dose of the Pfizer or Moderna vaccine.
• Individuals aged 12 or older with certain immunocompromising conditions who received a first booster dose of either vaccine are eligible for a second booster dose of the Pfizer vaccine.
• Individuals aged 18 or older with certain types of immunocompromising conditions who received a first booster dose of either vaccine are eligible for a second booster dose of the Moderna vaccine.

Some important details about these recommendations include the following:

• This booster vaccine is for people who received their first booster at least four months ago.
• This fourth shot would be of either the Moderna or Pfizer vaccines, not the Johnson & Johnson vaccine.
• Even if you were previously vaccinated with the Johnson & Johnson vaccine, it is now recommended that this booster be a Moderna or Pfizer vaccine only.
• For those who are immunocompromised and received a three-dose primary vaccination followed by an initial booster, this booster would count as their fifth shot.

Are People With MS Eligible for a Second Booster?

The National Multiple Sclerosis Society supports COVID-19 vaccination for people with multiple sclerosis. Your eligibility for a second booster depends on your age and the status of your immune system. If you have MS and are over 50 years old, it is recommended that you receive a second booster at least four months after your first booster shot.

Not all people with MS are immunocompromised. Some disease-modifying therapies for MS can suppress your immune system. According to the CDC, you may be considered immunocompromised if you take any of the following DMTs:

• Sphingosine 1-phosphate receptor modulators such as fingolimod (Gilenya), siponimod (Mayzent), ozanimod (Zeposia), and ponesimod (Ponvory)
• Alemtuzumab (Lemtrada)
• Anti-CD20 monoclonal antibodies including ocrelizumab (Ocrevus), ofatumumab (Kesimpta), rituximab (Rituxan), and biosimilars

People with MS who are immunocompromised and over the age of 12 are technically eligible for a second booster, but it is advised that you make that decision with your MS care team.

Read more about vaccine guidance at the National Multiple Sclerosis Society website. If you need help finding a location to get a second booster or any COVID-19 vaccine, use the vaccines.gov website.

How Effective Is the Moderna Vaccine in Immunocompromised Individuals?

These recommendations follow promising new results about the effectiveness of the vaccines in immunocompromised people. A recent study from Moffitt Cancer Center included people diagnosed with blood cancers, like leukemia, and people with solid tumors in their organs. Researchers tested levels of antibodies, the proteins the immune system makes to help destroy a target. In this case, the antibodies were to the SARS-CoV-2 virus that causes COVID-19, made in response to the Moderna COVID-19 vaccine.

After the second vaccine dose, about 90 percent of the people in the study developed antibodies against the coronavirus. About 98 percent of people with solid tumors showed an antibody response, while nearly 85 percent of people with blood cancers responded.

The lowest response — around 30 percent — was seen among people with chronic lymphocytic leukemia or B-cell non-Hodgkin lymphoma who were also receiving immunosuppressive therapy. But their response was much higher — nearly 73 percent — when they were not receiving treatment at the time of vaccination.

People receiving certain treatments, including rituximab less than six months before vaccination, had a lower immune response to the vaccine. People who’d had autologous (self) stem cell transplants in the past year or allogeneic (donor) stem cell transplants had a stronger response to the vaccine.

How Effective Is the Pfizer Vaccine in Immunocompromised Individuals?

Other research has looked at the response of immunocompromised individuals to the Pfizer vaccine. In one study, around 72 percent of people who were immunocompromised produced antibodies in response to the Pfizer vaccine. Another study showed immune system response in people with a wide variety of immunocompromising conditions was, on average, about 67 percent.

However, people with some health conditions were much more responsive to the Pfizer vaccine than others. For instance:

• People with HIV made antibodies in response to the Pfizer vaccine 98.7 percent of the time (a similar rate as the general population).
• People with multiple myeloma responded nearly 80 percent of the time.
• About 45 percent of people with kidney transplants responded to the vaccine.

A study looking at both mRNA vaccines in immunocompromised people living with HIV or solid organ transplants found the Pfizer vaccine had a similar response rate (about 94 percent) to the Moderna vaccine (around 92 percent).

Why These Results Matter

Although these studies do not directly address third doses or booster shots, additional doses of mRNA vaccines may increase detectable antibodies in a similar way to the first and second doses. Other research tells us antibody levels are likely to decrease over time, so getting booster doses at recommended intervals is necessary — even for vaccinated people who made antibodies after their initial shots.

Simply making antibodies does not always translate to complete immunity from COVID-19 infection. The findings from these studies are a good sign that mRNA vaccines for COVID-19 can trigger strong responses, even from people with compromised immune systems. It’s evidence that vaccines can protect people at higher risk of severe infections.

According to the CDC, getting vaccinated is still the best way to protect yourself and slow the spread of the virus. If you are unvaccinated because you had an immunodeficiency or autoimmune disease, were being treated for cancer, or are an organ transplant recipient, this new research should give you confidence to speak with your health care provider about when a COVID-19 vaccine would be right for you.

With the CDC now recommending a second COVID-19 booster and the omicron variant declining, now is an excellent time to get vaccinated and give your body a chance to build up immunity before a possible next wave of the pandemic.

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