I Got the J&J COVID Shot, Now What? Scientists Say Don't Worry as CDC Changes Guidance

People who have already had the Johnson & Johnson (J&J) COVID vaccine shouldn't panic after the recommendation to get another shot instead, scientists have said.

On Thursday, the U.S. Centers for Disease Control and Prevention (CDC) and the Advisory Committee on Immunization Practices (ACIP) met to discuss the risks versus the benefits of J&J's Janssen vaccine as well as a reported side effect known as TTS, or thrombosis with thrombocytopenia syndrome.

They recommended that people should receive an mRNA-type COVID vaccine like the Moderna or Pfizer shot instead of the J&J vaccine where possible.

The decision was based on "vaccine effectiveness, vaccine safety and rare adverse events, and consideration of the U.S. vaccine supply," the CDC said.

The J&J vaccine as well as the AstraZeneca shot—both adenoviral vector-type vaccines—are linked to higher rates of TTS than their mRNA counterparts.

TTS is a condition characterized by blood clots with a low platelet count, and is described by the CDC as serious, but rare.

As of December 8, 2021, there had been 57 confirmed reports of people developing TTS after getting the J&J vaccine out of more than 16.9 million doses administered. This compares to three confirmed TTS cases in people who had gotten the Moderna mRNA vaccine shot. There have been more than 458 million mRNA vaccines administered in the country.

Dr Alexander Edwards associate professor in biomedical technology at the Reading School of Pharmacy, the University of Reading, told Newsweek: "I'd advise anyone to follow the advice of their local healthcare professional, and not be concerned by rare side effects of any medicine.

"The most important thing to remember is that there is far more risk of serious illness from COVID-19 infection than for the vaccine. In that sense the vaccine remains safe and effective.

"It's really hard to make sense of these very rare risks, so what does it mean for people who have received the J&J vaccine? If you have had the J&J vaccine recently, and experience unusual symptoms, check with a healthcare professional. The adverse events typically happen within 1-2 weeks of the vaccine so if you had the vaccine a while ago, you'll be protected from harm from COVID-19 and there is no long-term risk."

The point was echoed by Ian Jones, a professor of virology also at the University of Reading. He told Newsweek that the CDC's recommendation marks a preference for mRNA vaccines due to "unrivalled performance, safety and availability."

Future Vaccination Plan

"The shift is all about future vaccination, including boosters. It does not imply that anyone who has had one is at risk," he added.

According to the CDC and ACIP, the median time from people getting the J&J shot to developing TTS symptoms was nine days with a range of zero to 18 days.

The median time from symptom onset to admission was five days with a range of zero to 30 days.

This was based on analysis of 54 TTS cases observed in people vaccinated between March 2 and August 31, according to a CDC/ACIP update on Thursday. Of those 54, all were hospitalized and eight died. There have been nine deaths due to TTS in total following a J&J vaccination, the CDC noted as of December 16.

The CDC noted on November 15 that "women younger than 50 years old especially should be made aware of a rare risk of blood clots with low platelets after vaccination" and that people should be "on the lookout" for possible symptoms several weeks after vaccination, including: severe or persistent headaches or blurred vision; shortness of breath; chest pain; leg swelling; persistent abdominal pain; and easy bruising or tiny blood spots under the skin beyond the injection site.

It said people should seek medical care right away if one or more of these symptoms develop.

In a statement following the CDC/ACIP recommendation, J&J said: "Johnson & Johnson remains confident in the overall positive benefit-risk profile of its COVID-19 vaccine.

"Johnson & Johnson continues to collaborate with health authorities around the world to ensure healthcare professionals and individuals are fully informed on reports of TTS, enabling correct diagnosis, appropriate treatment, and expedited reporting."

Janssen COVID vaccine
A pharmacist holds a vial of the Janssen vaccine at the U.S. Department of Veterans Affairs' VA Boston Healthcare System's Jamaica Plain Medical Center in Boston, Massachusetts, on March 4, 2021. The CDC has recommended that people get an mRNA vaccine instead if possible. Joseph Prezioso/AFP/Getty