COVID shots still work, but researchers seek further improvements

COVID-19 vaccines are at a critical juncture as companies test whether new approaches such as combination injections or nasal drops can keep up with a mutating coronavirus, though it’s unclear if changes are needed. .

There is already public confusion about who should get a second booster now and who can wait. There is also debate about whether almost everyone might need an extra dose in the fall.

“I’m very concerned about booster fatigue” causing a loss of confidence in vaccines that still offer very strong protection against the worst outcomes of COVID-19, said Dr. Beth Bell of the University of Washington, an adviser to the US Centers for Disease Control and Prevention.

Despite success in preventing serious illness and death, there is growing pressure to develop better vaccines to fend off milder infections, as well as options to counter terrifying variants.

“It seems like we do a fire drill every quarter, every three months or so” when another mutant sparks frantic testing to determine if injections are working, Pfizer vaccines chief Kathrin Jansen said at a recent Academy meeting. of Science in New York.

Still, seeking improvements for the next round of vaccines may seem like a luxury for American families anxious to protect their youngest children, children under 5 who are not yet eligible to receive a vaccine. Dr. Jacqueline Miller of Moderna told The Associated Press that her request to give two low-dose injections to the youngest children would be submitted to the Food and Drug Administration “fairly soon.” Pfizer has not yet reported data on a third dose of its extra-small injection for young children, after two were not strong enough.

COMBINATION SHOT MAY BE NEXT

The original COVID-19 vaccines continue to strongly protect against serious illness, hospitalization, and death, especially after a booster dose, even against the most contagious variants.

Updating the vaccine recipe to match the latest variants is risky, because the next mutant might not be related at all. So companies are following the example of the flu vaccine, which offers protection against three or four different strains in a single shot each year.

Moderna and Pfizer are testing the 2-in-1 COVID-19 protection they hope to offer this fall. Each “bivalent” injection would combine the original vaccine tested with a version targeted at omicrons.

Modern has a clue the approach might work. He tested a combined injection targeting the original version of the virus and an earlier variant called beta, and found that vaccine recipients developed modest levels of antibodies capable of fighting not only beta but also newer mutants like omicron. Moderna is now testing its bivalent candidate targeting omicron.

But there is an imminent deadline. The FDA’s Dr. Doran Fink said that if updated injections are to be given in the fall, the agency would have to decide on a prescription change in early summer.

DON’T EXPECT REINFORCEMENTS EVERY FEW MONTHS

For the average person, two doses of the Pfizer or Moderna vaccine plus a booster — a total of three shots — “sets you up” and prepares you for what may turn into an annual booster, said Dr. David Kimberlin, an adviser to the University of Alabama at Birmingham CDC.

After that first booster, CDC data suggests that an additional dose offers most people an incremental temporary benefit.

Why the emphasis on three shots? Vaccination triggers the development of antibodies that can defend against coronavirus infection, but which naturally decline over time. The next line of defense: memory cells that spring into action to create new virus fighters if an infection infiltrates. The Rockefeller University researchers found that those memory cells become more powerful and capable of attacking more diverse versions of the virus after the third shot.

Even if someone who’s vaccinated gets a mild infection, thanks to those memory cells “there’s still plenty of time to protect against serious illness,” said Dr. Paul Offit of the Children’s Hospital of Philadelphia.

But some people, those with severely weakened immune systems, need more doses up front to have a better chance of protection.

And Americans over the age of 50 are being offered a second booster, following similar decisions by Israel and other countries that offer the additional opportunity to give older people a little more protection.

The CDC is developing tips to help eligible people decide whether to get an extra shot now or wait. Among those who might want a second booster sooner are the elderly, people with health conditions that make them particularly vulnerable, or those who are at high risk of exposure through work or travel.

COULD NASAL VACCINES BLOCK INFECTION?

It is difficult for an injection in the arm to form many virus-fighting antibodies inside the nose, where the coronavirus attaches itself. But a nasal vaccine could offer a new strategy to prevent infections that disrupt people’s daily lives, even if they are mild.

“When I think about what getting a second booster would do to me, I really want to prevent infections,” said Dr. Grace Lee of Stanford University, who chairs the CDC’s immunization advisory committee. “I think we have to do better.”

Nasal vaccines are difficult to develop and it is unclear how quickly they might be available. But several are in clinical trials worldwide. One in late-stage testing, made by India’s Bharat Biotech, uses a chimpanzee cold virus to deliver a harmless copy of the coronavirus spike protein to the lining of the nose.

“I certainly don’t want to abandon the success we’ve had” with COVID-19 vaccines, said Dr. Michael Diamond of Washington University in St. Louis, who helped create the candidate now licensed to Bharat.

But “we are going to have a hard time stopping transmission with current systemic vaccines,” Diamond added. “We’ve all learned that.”

___

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.

Add Comment