COVID shots still work, but researchers are chasing new improvements

COVID-19 vaccinations are at a critical time as companies test whether new approaches such as combination syringes or nasal drops can keep up with a mutating coronavirus – although it is not clear if changes are needed.

There is already public confusion about who should get a new booster now and who can wait. There is also debate as to whether just about anyone may need an extra dose in the fall.

“I am very concerned about booster fatigue,” which causes a loss of confidence in vaccines that still provide very strong protection against COVID-19’s worst outcome, said Dr. Beth Bell of the University of Washington, counselor for the U.S. Centers for Disease Control and Prevention.

Despite success in preventing serious illness and death, there is growing pressure to develop vaccines that are also better at warding off milder infections – as well as opportunities to counter scary variants.

“We undergo a fire drill, it looks like every quarter, every three months or so,” when another mutant does hectic tests to determine if the shots last, Pfizer vaccine chief Kathrin Jansen told a recent meeting of the New York Academy of Sciences.

Still, seeking improvements for the next round of vaccinations may seem like a luxury to American families eager to protect their youngest children – children under the age of 5 who are not yet eligible for a shot. Modernas Dr. Jacqueline Miller told the Associated Press that her application to provide two low-dose injections to the youngest children would be submitted to the Food and Drug Administration “pretty soon.” Pfizer has not yet reported data on a third dose of its extra small shot for children after two did not prove to be strong enough.


The original COVID-19 vaccines remain highly protective against serious illness, hospitalization and death, especially after a booster dose, even against the most contagious variants.

It is risky to update the vaccine recipe to match the latest variants because the next mutant may be completely independent. So companies are based on the flu vaccine, which provides protection against three or four different strains in one shot each year.

Moderna and Pfizer are testing 2-in-1 COVID-19 protection, which they hope to offer this fall. Each “bivalent” shot would mix the original, documented vaccine with an omicron-targeted version.

Modern has a hint the access could work. It tested a combination shot 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 just beta but also newer mutants like omicron . Moderna is now testing its omicron-targeted bivalent candidate.

But there is a looming deadline. FDA’s Dr. Doran Fink said that if any updated shoots are to be given in the fall, the agency must decide on a recipe change before early summer.


For the average person, “two doses of the Pfizer or Moderna vaccine plus a booster – a total of three shots – will get you ready” and ready for what could become an annual booster, said Dr. David Kimberlin, a CDC adviser from the University of Alabama at Birmingham.

After the first booster, CDC data suggest that an extra dose gives most people a step-by-step, temporary benefit.

Why is emphasis on three shots? Vaccination triggers the development of antibodies that can stave off coronavirus infection but naturally decrease over time. The next line of defense: Memory cells that jump in to create new virus-fighters if an infection sneaks in. Rockefeller University researchers found that these memory cells became more potent and able to target several different versions of the virus after the third shot.

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

However, some people – those with severely weakened immune systems – need more doses in advance for a better chance of protection.

And Americans 50 and older are being offered an extra booster, following similar decisions by Israel and other countries that offer the extra chance to give older people a little more protection.

The CDC is developing advice to help eligible people decide whether to get an extra shot now or wait. Among those who may want an extra booster faster are the elderly, people with health problems that make them particularly vulnerable, or who are at high risk of exposure from work or travel.


It is difficult for a shot in the arm to form lots of antiviral antibodies inside the nose where the coronavirus gets stuck. But a nasal vaccine may offer a new strategy to prevent infections that disrupt people’s daily lives, even if they are mild.

“When I think about what would make me get a new booster, I would actually like to prevent infection,” said Dr. Grace Lee from Stanford University, who chairs the CDC’s Immunization Advisory Committee. “I think we need to do better.”

Nasal vaccines are difficult to develop and it is not clear how quickly anyone could become available. But more are in clinical trials globally. A late-stage test, manufactured by India’s Bharat Biotech, uses a chimpanzee cold virus to deliver a harmless copy of the coronavirus tip protein to the nasal mucosa.

“I certainly do not want to give up the success we have had” with COVID-19 shots, said Dr. Michael Diamond from Washington University in St. Louis, who helped create the candidate now licensed for Bharat.

But “we’re having a hard time stopping the transmission with the current systemic vaccines,” Diamond added. “We have all learned that.”


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

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