On Friday, the Center for Disease Control and Prevention’s Advisory Committee for Immunization Practices (ACIP) unanimously greenlit a new vaccine from Merck that protects against 21 strains of Streptococcus pneumoniae (S. pneumoniae), bacteria that can cause invasive pneumococcal diseases, including pneumonia. The move follows approval from the Food and Drug Administration earlier this month.

The vaccine, called Capvaxive (PSV21), is now recommended for the following groups:

• Adults 65 and older, regardless of whether or not they’ve had a prior pneumonia vaccine.
• Adults 19-64 years of age with certain underlying medical conditions or risk factors who have not previously received a pneumonia vaccine (or are uncertain if they’ve ever had one).
• Adults 19 years and older who received a previous dose of pneumonia vaccine Prevnar 13 or a complete series of Pneumovax 23.

The committee also recommended that individuals 65 and older who received both Prevnar 13 and Pnumovax 23 ask their providers if a dose of Capvaxive would be appropriate for them.

“We are very happy to have the formal approval from the Food and Drug Administration (FDA), which supports our indication for preventing invasive pneumococcal disease in adults,” Heather Platt, MD, Distinguished Scientist for Merck, told Verywell.

Here’s what you should know about the updated vaccine and whether it might be one to add to your immunization to-do list this year.

Why Do We Need a New Vaccine Against Pneumococcal Disease?

Over 100 strains of S. pneumoniae are known to cause illnesses like ear infections, sinus infections, bacterial meningitis, and pneumonia. Pneumonia vaccines protect against the most common strains of pneumococcal bacteria that cause these illnesses.

Invasive pneumococcal disease (IPD) occurs when S. pneumoniae grows in a normally sterile body site, such as blood, cerebrospinal fluid, pleural fluid surrounding the lungs, and the fluid around the joints.

Pneumococcal infections can be serious and are responsible for over 150,000 hospitalizations for pneumonia and 2,000 cases of meningitis in the United States annually. Pneumonia is the most common type of pneumococcal infection.

Merck’s first pneumonia vaccine, Pneumovax 23, received FDA approval in 1983, and it is still one of the most frequently administered pneumonia vaccines. Since then, other FDA-approved pneumonia vaccines developed include Vaxneuvance and Prevnar.

Epidemiologists follow the strains of S. pneumoniae that are causing invasive pneumococcal disease and pneumonia in the general public. Between 2018 and 2021, they found that eight S. pneumoniae serotypes not covered by existing vaccines were responsible for around 27% of invasive pneumococcal disease in adults over 50 and about 31% in those aged 65 and older.

“Capvaxive covers these specific serotypes which are not covered by the existing pneumococcal vaccine options,” said Shirin Mazumder, MD, an infectious disease specialist at Methodist Le Bonheur Healthcare in Tennessee.

While Capvaxive is only recommended for people 19 and older, individuals 18 and younger can still get other pneumonia vaccines that are currently on the market. A clinical trial will begin soon to assess Capvaxive’s safety and efficacy in children ages 2 to 17.

How Are New Vaccines Tested for Safety?

New vaccines are being developed all the time, but it takes many safeguards to actually bring them to market.

“Vaccines undergo rigorous scientific testing before they are approved by the FDA. There are several layers of approval by different committees and groups that new vaccines must go through before becoming available to the general public,” said Mazumder. “This process helps ensure that the vaccine is safe and benefits from the currently available options.”

Capvaxive was studied in multiple phase 3 clinical trials, which consistently demonstrated a significant immune response when compared to several other pneumococcal vaccines that are currently available.

“The various trials involving Capvaxive demonstrated both efficacy in the vaccine’s protection and safety,” said Mazumder.

Public health advocates like Mazumder are optimistic that the vaccine will provide a more effective guard against pneumonia-causing bacteria and their complications once it reaches the public.

“Capvaxive will help prevent more pneumococcal infections, hospitalizations, and death due to invasive pneumococcal disease,” said Mazumder.