If you are immunocompromised, you should get your third dose of a COVID-19 vaccine when you can, doctors say.

Last week, the Centers for Disease Control and Prevention authorized third doses of the Moderna and Pfizer vaccines for those who are moderately to severely immunocompromised. This includes people being treated for cancer, organ and stem cell transplant recipients, those taking high-dose corticosteroids, HIV patients and patients with moderate to severe immunodeficiency.

The hope is that a third dose will boost the immune response in people who are most vulnerable to adverse effects should they contract COVID-19.

Studies of people with specific conditions that make them more vulnerable to COVID-19 found that the two-dose mRNA vaccines might not have produced high enough antibody levels to fight off the virus. One study of more than 600 transplant patients found that just 54% of those who were fully vaccinated developed antibodies.

Limited studies so far show that a third dose might boost those low antibody levels in these patients. Countries including France, Germany, the United Kingdom and Israel also plan to authorize third doses for similar patient populations.

The pandemic has been more risky for patients with underlying health conditions, and that reality persists today with the fast-spreading delta variant causing a surge in cases and hospitalizations state and nationwide.

Immunocompromised patients can receive a third dose as soon as four weeks after their second dose of either the Pfizer or Moderna mRNA vaccine.

Those who received the single-dose Johnson & Johnson vaccine are not included in the third dose recommendation yet, as the CDC weighs data on the effectiveness of a second dose .

Dr. Arvind Chaudhry, the director of Summit Cancer Centers, said the phones have been ringing off the hook with patients trying to get their third dose. Chaudhry recommends it, noting that some cancer patients have tested positive for the virus, despite being fully vaccinated.

“There is an actual need for the shot,” Chaudhry said.

Breakthrough cases, while rare, are increasingly common with the delta variant circulating, and patients who are immunocompromised or with underlying health conditions are at higher risk for this.

There have been 5,879 breakthroughs statewide as of Aug. 11, including 380 in Spokane County . So while rare, the risk is still there. More than 8.3 million doses of vaccine have been given statewide.

The hope is that a third dose will offer enough protection to keep immunocompromised patients out of the hospital should they test positive for the virus.

One study found that 40% to 44% of breakthrough cases who are hospitalized are also immunocompromised, according to an analysis presented to the Advisory Committee on Immunization Practices.

The third dose is different from a booster dose, according to the CDC, which might become available later this fall to all fully vaccinated people when vaccines have potentially waned in effectiveness.

Vaccination is highly effective at keeping people out of the hospital with COVID-19, even with the delta variant on the rise. In recent weeks, more than 90% of those people hospitalized with the virus in Spokane County have not been vaccinated against the virus, according to the health district.

With the vast majority of breakthrough cases, while they might bring symptoms, they are not requiring hospitalization.

At Cancer Care Northwest, most patients were eager to get vaccinated and now get their third dose, said Dr. Hakan Kaya, a medical oncologist.

Some cancer patients, like those with leukemia or other blood cancers, already have stressed immune systems. For other cancer patients, chemotherapy and radiation can weaken the immune system too, Kaya said.

Vaccines are available at most pharmacies, some grocery stores and many health care providers throughout the county.

The best way to protect immunocompromised individuals beyond their own third doses is for more people in the community at large to get vaccinated against the virus and help reduce virus transmission.

As Kaya noted, one of his patients is at much higher risk even walking into a grocery store or an environment where not everyone is vaccinated than someone with no underlying medical conditions. Vaccination then, is the way to protect the most vulnerable.

“Not receiving a vaccine is actually putting other people’s lives at risk, especially my patients,” Kaya said.