COVID-19 single-shot vax cleared for use again

Johnson & Johnson’s single-shot COVID-19 vaccine is safe for use in individuals 18 years of age and older, but it will likely come with a warning label, says the US Centers for Disease Control and Prevention (CDC).

After a careful review, the US Food and Drug Administration and the CDC on April 23 lifted their earlier recommendation to temporarily hold the use of the vaccine over reports of rare blood clots, saying the benefits of inoculation outweighed the potential risks. Their decision followed a vote of 10-4 and one abstention, by the CDC Advisory Committee on Immunization Practices (ACIP), to recommend the use of the J&J vaccine again.

“This vaccine was shown to be safe and effective for the vast majority of people,” said CDC director Dr Rochelle Walensky, though she cautioned that some women might be at risk of rare blood-clotting issues.

Dr Rochelle Walensky

To alert doctors and vaccine recipients of the potential but exceedingly rare risk, J&J and the FDA plan to add a warning about the risks of thrombosis with thrombocytopenia syndrome (TTS) to the vaccine label and the FDA emergency use authorization fact sheet. This could help younger women and their doctors decide if they should take the shot or opt for an alternative.

The decision clears the way for the distribution of millions of doses to vulnerable groups who need the one-shot vaccine the most.

Health & safety first

The April 13 pause on J&J mass vaccination was prompted by reports of six cases of cerebral venous sinus thrombosis (CVST) with thrombocytopenia out of the more than 7 million people who received the shots. Since then another nine cases had been reported. All were women, three of whom died. Of the 15 TTS cases, 12 were CVST.

The CDC was then worried that cases could increase as the new vaccine is rolled out in the country. Thankfully, the clotting risk was rare as officials had hoped it would be. The overall rate of events was 1.9 cases per million people.

“Above all else, health and safety are at the forefront of our decisions,” said Walensky. “We’ve identified exceptionally rare events out of millions of doses administered, and we paused to examine those events more carefully. As we always do, we will continue to watch all signals closely as more people are vaccinated.”

The J&J vaccine (Ad26.COV2.S) is FDA-approved for emergency use in adults. The vaccine is composed of a recombinant, replication-incompetent human adenovirus type 26 (Ad26) vector. It is intended to encode a stabilized form of SARS-CoV-2 spike (S) protein.

By comparison, the Pfizer and Moderna vaccines use a different mechanism that relies on mRNA. This approach mimics what the SARS-CoV-2 does in nature, but the vaccine mRNA codes only for the critical fragment of the viral protein. This gives the immune system a preview of what the real virus looks like without causing disease and time to design powerful antibodies that can neutralize the real virus if the person gets infected.

No vaccine is better than another

Meanwhile, experts urged people against parsing vaccine studies in minute detail and seeking to choose their shots. “It is important that we do not think that one vaccine is better than another,” said FDA adviser Dr H. Cody Meissner from Tufts University School of Medicine in Boston, Massachusetts, US.

“We recommend people with questions about which vaccine is right for them to have those discussions with their healthcare provider,” added acting FDA commissioner Dr Janet Woodcock.

One-shot vaccine better-suited for some

The J&J vaccine was 66 percent effective overall in preventing moderate-to-severe COVID-19, 28 days after vaccination. At least 14 days after vaccination, vaccine efficacy was 72 percent in the US, 68.1 percent in Brazil,  and 64 percent in South Africa.

The vaccine is not only easier to give, it is also easier to store as it only requires normal fridge temperatures of 2–8°C (36–46°F) unlike other vaccines that require ultracold temperatures.

“In terms of benefits, we found that for every 1 million doses of the J&J vaccine, we could prevent over 650 hospitalizations and 12 deaths among women aged 18-49,” Walensky reported. In women 50 years or older, the benefits were greater as the vaccine could prevent 4,700 hospitalizations and 650 deaths.

Some experts say the one-dose shot is better-suited for a population that can be difficult to reach twice, including the homeless or the disabled. The strategy is to bring the vaccine to the person, rather than the person to the vaccine.