CDC Panel Updates Info on Rare Side Effect After J&J Vaccine

Brenda Goodman, MA

July 22, 2021

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Despite recent reports of Guillain-Barré Syndrome (GBS) after the Johnson and Johnson vaccine, independent experts who advise the Centers for Disease Control and Prevention (CDC) on the use of vaccines agree the benefits of the one-dose shot still outweigh its risks. 

The company also presented new data suggesting that the shots generate strong immune responses against circulating variants and that antibodies generated by the vaccine stay elevated for at least 8 months.

Members of the Advisory Committee on Immunization Practices (ACIP) did not vote, but discussed and affirmed their support for recent decisions by the US Food and Drug Administration and CDC to update patient information about the very low risk of Guillain-Barré Syndrome that appears to be associated with the vaccine, but to continue offering the vaccine to people in the US.

The Johnson and Johnson shot has been a minor player in the US vaccination campaign, accounting for less than 4% of all vaccine doses given in this country. Still, the single-dose inoculation, which doesn't require ultra-cold storage, has been important for reaching people in rural areas, through mobile clinics, at colleges and primary care offices, and in vulnerable populations — those who are incarcerated or homeless.

The FDA says it has received reports of 100 cases of GBS after the Johnson and Johnson vaccine through its Vaccine Adverse Event Reporting System database through the end of June. The cases are still under investigation.

To date, more than 12 million doses of the vaccine have been administered, making the rate of GBS 8.1 cases for every million doses administered.

Although still extremely rare, that's above the expected background rate of GBS of 1.6 cases for every million people, said Grace Lee, MD, a Stanford pediatrician who chairs the ACIP's Vaccine Safety Technical Work Group. 

So far, most (61%) GBS cases have been among men. The midpoint age of the cases was 57 years. The average time to onset was 14 days, and 98% of cases occurred within 42 days of the shot.  Facial paralysis has been associated with an estimated 30%-50% of cases. One person, who had heart failure, high blood pressure, and diabetes, has died.

Still the benefits of the vaccine far outweigh its risks. For every million doses given to people over age 50, the vaccine prevents nearly 7500 COVID hospitalizations, and nearly 100 deaths in women and more than 13,000 COVID hospitalizations and more than 2400 deaths in men. 

Rates of GBS after the mRNA vaccines made by Pfizer and Moderna were around 1 case for every 1 million doses given, which is not above the rate that would be expected without vaccination.

The link to the Johnson and Johnson vaccine prompted the FDA to add a warning to the vaccine's patient safety information on July 12.

Earlier this month, the European Medicines Agency recommended a similar warning for the product information of the AstraZeneca vaccine Vaxzevria, which relies on similar technology.

Good Against Variants

Johnson and Johnson also presented new information showing its vaccine maintained high levels of neutralizing antibodies against four of the so-called "variants of concern" — Alpha, Gamma, Beta, and Delta. The protection generated by the vaccine lasted for at least 8 months after the shot, the company said.

 "We're still learning about the duration of protection and the breadth of coverage against this evolving variant landscape for each of the authorized vaccines," said Mathai Mammen, MD, PhD, global head of research and development at Janssen, the company that makes the vaccine for J&J.

The company also said that its vaccine generated very strong T-cell responses. T cells destroy infected cells and, along with antibodies, are an important part of the body's immune response.

Antibody levels and T-cell responses are markers for immunity. Measuring these levels isn't the same as proving that shots can fend off an infection. 

It's still unclear exactly which component of the immune response is most important for fighting off COVID.

Mammen said the companies are still gathering that clinical data, and would present it soon.

"We will have a better view of the clinical efficacy in the coming weeks," he said.

Brenda Goodman, MA, is a senior news writer for WebMD based in Atlanta.  Her work has appeared in The New York Times, Scientific American, Psychology Today, The Boston Globe, Self, Shape, Parade, U.S. News and World Report, and Atlanta Magazine. She has a master's degree in science and environmental reporting from New York University.

Follow me on Twitter: @ReporterGoodman

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