Study: COVID-19 booster shots less effective after 4 months but still provides protection

Posted at 4:12 PM, Feb 14, 2022
and last updated 2022-02-14 17:16:47-05

(WXYZ) — A new study looking at the effectiveness of COVID-19 booster shots found they offered high protection, but levels waned after four months.

I’m concerned the most for people who are at high risk for severe COVID-19. But I do want to point out that this study is just an early look at how effective Pfizer or Moderna shots were over a five-month period. Now, here’s what the researchers did: They analyzed over 241,000 visits to emergency or urgent care, as well as over 93,000 hospitalizations across 10 states.

They looked at people who were boosted and those who were only fully vaccinated. I'll break it all down:

I’ll start with people who were fully vaccinated and boosted, meaning they’ve received three shots. Researchers found the vaccines to be 87% effective against emergency or urgent care visits during the first two months. But at four months, that number dropped to 66%.

Regarding hospitalizations for people who were boosted, the vaccines were found to be 91% effective at two months, and that number dropped to 78% at the four-month mark.

Now not surprisingly, the numbers were lower for people who were fully vaccinated with two shots. Vaccine effectiveness against hospitalization fell from 71% at two months to 54% by at least five months.

To me, what the numbers show here is how effective booster shots are and that even though the vaccines wane, they still offer pretty good protection at month four.

Changing topics slightly, COVID-19 vaccine authorization for younger children 6 months to 5 years has been delayed.

Pfizer had initially filed with the Food and Drug Adminstration the first week of February. That was to review Pfizer’s data regarding two doses. But with omicron spreading so quickly and infecting so many children, new data showed that many children in Pfizer’s trials were getting infected at a higher rate than with the delta variant.

This indicated that the omicron variant is better at evading the vaccine’s two-dose protection, which wasn't that great to begin with for kids aged 2 to 4. Trials had shown it did not generate a very strong immune response for this age group. So, the FDA agreed to wait and see how well three shots work against omicron. This means more time is needed. Pfizer says the earliest they’ll have this data is in April.

Now, I know this is not making parents happy. I hear from many of my patients how anxious they are to get their youngest vaccinated, but it’s best to make sure the vaccines generate neutralizing antibodies.

In the meantime, parents should continue with pandemic precautions. It’s best that people around young children be fully vaccinated, preferably boosted. Masks should continue to be worn and I would recommend parents be choosy about who they see and where they go.

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