Vaccines against COVID-19 are saving countless lives, but they can't stem the chaos when a highly contagious new variant arrives on the scene, leaving people wondering: Are we going to need frequent boosters? A new formula? A new type of vaccine?
That's unclear, but now that current vaccines are doing their job, many experts caution against setting your sights too high.
"We have to reconsider what the goal of vaccination is," said Dr. Daniel Kuritzkes, chief of infectious diseases at Brigham & Women's Hospital. “It is unrealistic to think that any type of vaccination is going to protect people from infection, from mild symptoms, forever.”
If the goal is to prevent severe symptoms, "we might not need to make so many adjustments to the vaccines every time a new variant emerges."
The virus essentially changes by mutating, with no way of knowing how soon the next variant will be. A subvariant of -ómicron with its own unique mutations is already circulating. Studies are underway to create the next generation of vaccines that could offer as broad protection against future variants but they won't be ready any time soon.
The immediate fix: Vaccinating more people now "will reduce the opportunities for the virus to change and create new Greek letters that we have to worry about," said Jennifer Nuzzo of the Johns Hopkins Center for Health Security.
WHY ISN'T IMMUNITY PERFECT?
The task of blocking infection falls to antibodies, which are formed after a vaccination or infection with COVID-19, ready to respond the next time a person is exposed.
One problem: The mutations change the appearance of the protein that covers the coronavirus in the same way that a criminal changes his costume to evade capture.
This is why omicron was better able to penetrate the first defense than previous variants — its shell was more difficult for existing antibodies to recognize.
Also, the immune system isn't designed to be on constant alert, so infection-fighting antibodies wear off over time. Several months after two doses of the Pfizer or Moderna vaccines, people had little protection against an omicron infection — a result of both the disappearance of the antibodies and the mutation of the variant.
Luckily, other soldiers of the immune system, called T cells, are key to keeping an infection from turning into a serious illness — and that protection lasts longer because those cells recognize other parts of the virus that don't change as easily.
A THIRD DOSE MATTERS
After a booster dose, protection against symptoms caused by omicron is around 70% — not as good as the 94% for previous variants, but still very effective. Importantly, the dose strengthened protection against severe symptoms.
Scientists are closely monitoring to see if the antibodies persist after a third dose — but at some point, those levels are going to drop. The so-called memory cells can produce more the next time the body feels they are needed.
However, Israel is offering a certain dose for some people, including those 60 and older, and is considering giving the extra booster to all adults.
The debate is whether repeated boosters are really the best strategy, especially since dangerous new variants are less likely to form when more people around the world are vaccinated.
Constant boosters to keep antibody levels constantly elevated "is not a public health strategy that works," said Dr.
Paul Offit, a vaccine expert at the Children's Hospital of Philadelphia.
Pfizer and Moderna are testing boosters targeting the omicron variant among some adults in the United States, though it's unclear whether authorities would abandon a proven life-saving vaccine formulation in favor of an altered version in hopes of fewer infections than the others. vaccinated. Preparing a single injection with two types of vaccine is possible, but they would have to prove that the mixture does not weaken the original protection against severe symptoms.
NEW APPROACHES IN THE FUTURE
No matter what happens with omicron, it is clear that the coronavirus is not going to go away and the National Institutes of Health (NIH) in the United States are dedicating 43 million dollars to projects to develop the so-called “pan-coronavirus” vaccines, for protection against more than one type. One possibility: Nanoparticles that carry peplomer fragments of four and up to eight variants of the virus instead of just one type, as in the current ones.
It's a promising idea, but NIH infectious disease chief Dr. Anthony Fauci says it's years in the making. "I don't want anyone to think pan-coronavirus vaccines are close," he said.
A possibly more direct approach: Create vaccines for COVID-19 that can be sprayed into the nose to form ready-made anti-viruses to fight the disease where they initially find it. Nasal vaccines are more difficult to produce than injected versions, but efforts are underway including a large study announced by Bharat Biotech in India.
PROTECTION VARIES GLOBALLY
Complicating any change in vaccine strategy is the grim reality that only 10% of people in poor countries have received at least one dose. In addition, recent studies indicate that some types of vaccines used in the world seem to be more easily evaded by omicron than others, which means that strategies for boosters have to be adapted.
Studies at Yale University found no antibodies against omicron in the blood of people who received two doses of the Sinovac vaccine from China. Initial injections of Pfizer's booster — a very different vaccine — helped, but not enough, raising antibody levels only in those registered by Pfizer vaccinates who did not receive the booster.
Overshadowing all of that is the fact that "we don't know how to predict the next variant," said Dr. Jesse Goodman of Georgetown University, a former head of vaccinations for the US Food and Drug Administration. Goodman wants a new global strategy that defines what triggers a vaccine switch. "Otherwise we're going to have confusion in the public again," he said.