CDC finds booster protection wanes after 4 months, but UCSF doctor says immune response continues

ByLuz Pena KGO logo

Sunday, February 13, 2022

Doctor says immune response continues after booster shot wanes

The CDC announced the protection from a third COVID vaccine shot decreases after 4 months, but UCSF doctors say immune response continues.

SAN FRANCISCO (KGO) -- Roughly three months since boosters became available for Californians 18 and older, the CDC announced the protection from a third shot decreases after four months.

"What the booster did is increase production of antibodies for a while, 10 weeks to four months. Those antibodies are going to come down with time, but that doesn't mean your immune response wanes. It just means one aspect of the immune response. Your T-cells and B-cells are still there to protect you against severe disease," said Dr. Monica Gandhi, UCSF Infectious Disease and Professor of Medicine.

Dr. Gandhi highlighted that the first two doses of the vaccine continue to be highly effective against the virus. Those doses prime the body to respond anytime.

Long COVID symptoms can include pain, fatigue and brain fog weeks or months after the initial infection.

"Our T-cells and our B-cells are still there. The B-cells are the recipe to make more antibodies and they can make antibodies anytime they see COVID and may take a couple days. T-cells will help them make antibodies," said Dr. Gandhi.

During this early look at the performance of the booster, researchers found that the vaccine effectiveness against hospitalization remained high at 78%, four months after the third dose. Dr. Maria Raven, Chief of Emergency Medicine at UCSF has noticed the difference in patients.

"People that are getting the booster seem to be getting less sick. They are not necessarily protected from getting infected 100%, but they are getting less sick," said Dr. Raven.

As we are inching up to month four since many got boosted, Dr. Raven has a new concern.

"High risk people whose booster immunity may be waning might be at high risk of hospitalization now that we are coming to that 3-4 month mark. I would say the encouraging thing though is that case rates over all are decreasing," said Dr. Raven.

Now, the question is:

Luz Pena: "Will we need a fourth shot?"

Dr. Gandhi: "I don't think that as a general population we will, but I think certain groups always will. Immunocompromised already approved for fourth booster and I think older people depending on how much COVID is circulating."

Dr. Gandhi believes we are about one month away from an endemic in California. Meaning there will be COVID cases in our population, but it will be easier to manage the virus.

"We have the tools to control it and keep our hospitalizations low. Those two tools are vaccination and therapeutics," said Dr. Gandhi.

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