Only because Pfizer plans to offer Covid-19 vaccine boosters doesn’t mean people will be lining up anytime soon – U.S. and international health officials say the fully vaccinated appear to be well protected for now.
Experts around the world are closely monitoring whether and when people need another exposure. At the same time, many are suggesting that vaccination should be a priority for now, noting that worrisome coronavirus mutants wouldn’t emerge anytime soon if more of the US and the rest of the world had received the first round of vaccinations.
“If you’re going to stop hearing about the variant of the week,” said Jennifer Nuzzo, a public health specialist at Johns Hopkins University, “we need to do more to ensure that all countries have more access to vaccines.”
Here are some questions and answers about vaccine immunity and boosters.
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WHAT DOES THE WHOLE BOOSTER DEBATE INVITE?
US health officials have long said that one day people might need a booster dose – after all, they will need it for many other vaccines. For this reason, studies are being conducted to test different approaches: simple third doses, mix-and-match tests with a different brand for a third dose, or experimental boosters that are better tailored to different variants.
But last week Pfizer and its German partner BioNTech announced that they were planning to seek approval of a third dose through the Food and Drug Administration in August as it could increase levels of virus-fighting antibodies and ward off potentially worrisome mutants.
The companies haven’t released any data, and US health officials gave a sharp response that boosters are not yet needed and that the government, not vaccine manufacturers, will decide if and when this changes.
The World Health Organization announced on Monday There isn’t enough evidence that a third dose is needed. It was said that the narrow shots should be shared with poor countries rather than used as boosters by rich countries.
WHAT IS THE EVIDENCE THAT VACCINE PROTECTION REMAINS STRONG?
An Associated Press analysis last month found that almost all Covid-19 deaths in the US occur among unvaccinated people.
In recent weeks, infections and hospital stays have increased with the spread of the highly contagious Delta variant. But the Centers for Disease Control and Prevention say the increases are being driven by the least vaccinated parts of a country, where there are lots of vaccinations if only people would take them.
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No vaccine is perfect, which means that people who are fully vaccinated will occasionally become infected, but these so-called breakthrough cases are usually mild. Officials monitoring the need for boosters are watching closely to see if there is any surge in serious breakthrough infections.
So far, the news is good: the people who were in the first place for vaccines in December and January don’t seem to be at any higher risk of breakthrough infections than those who were recently vaccinated, said Dr. Jay Butler of the CDC on Tuesday.
IS THE BOOSTER QUESTION ALL ABOUT NEW VARIANTS?
No, scientists also observe how much the vaccinated people’s overall immunity to the coronavirus decreases. That too might require a booster shot.
Virus-fighting antibodies gradually decrease. This is normal as the body doesn’t have to be on high alert forever.
But antibodies aren’t its only defense. When these levels go down, the body has made backups. These include memory B cells that “explode and divide like crazy” on next contact to make new antibodies, said University of Pennsylvania immunologist Scott Hensley.
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Another backup: T cells that kill virus-infected cells to prevent a breakthrough case from becoming serious.
Laboratory studies signal that antibodies against the Delta variant are not as strong as against some previous versions of the coronavirus, but are still protective. Specialists are more concerned about the prospect of future mutants that could escape today’s vaccines, something that can only be prevented by tackling the spread of the virus everywhere.
HOW ARE OTHER COUNTRIES AGAINST THE DELTA VARIANT?
Real world data from England, Scotland, Canada and Israel show that the vaccines most widely used in Western countries continue to offer strong protection. For example, researchers in the UK found that two doses of the Pfizer vaccine containing the Delta variant were 96 percent effective against hospitalization and 88 percent effective against symptomatic infections.
Israel recently reported preliminary data suggesting protection from mild delta infection has dropped to 64 percent. But the protection against serious illnesses remained high.
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There is less information on how well other vaccines perform against the Delta variant. Thailand announced this week that health workers who had received two doses of a Chinese vaccine would receive a booster shot from AstraZeneca.
COULD SOME PEOPLE NEED A BOOSTER BEFORE THE WHOLE POPULATION?
That is possible. Israel has just started distributing third doses of the Pfizer vaccine to transplant recipients and other patients with weak immune systems. The reason: People who take certain immunosuppressive drugs do not react as strongly to vaccinations – not just to Covid-19 vaccines – as healthy people.
France already had a similar third dose policy for the immunocompromised. And while it’s not approved in the U.S., some transplant recipients are asking for a third dose in hopes of more protection.
It has not yet been proven whether a third dose helps and who needs which and when. The strategy’s first major study begins with thousands of patients in Norway.
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