Pfizer and BioNTech announced on Thursday that they are developing a version of the coronavirus vaccine that targets Delta, a highly infectious version that has spread to nearly 100 countries. The companies expect the clinical trial of the vaccine to start in August.
Pfizer and BioNTech also reported promising results from studies of people who received third dose of original vaccine. The booster, given six months after the second dose of the vaccine, increases the potency of antibodies against the original virus and the beta version by five to ten times, the companies said.
The vaccine’s effectiveness may decrease six months after vaccination, the companies said in a news release, and booster doses may be needed to prevent the types of virus.
The data has not been published, nor is it peer-reviewed. Vaccine makers said they expected to submit their findings to the Food and Drug Administration in the coming weeks, a step toward obtaining authorization for booster shots.
But the companies’ claims contradict other research, and many experts clamored against the claim that boosters would be needed.
“Given the variants we have at this time, there’s really no indication for a third booster or a third dose of an mRNA vaccine,” said Dr. Céline Gounder, an infectious disease specialist at Bellevue Hospital Center in New York. “In fact, many of us question whether you’ll ever need a booster.”
Federal agencies also made a questionable remark on Thursday night. In general, Americans who have been fully vaccinated do not need a booster shot at this time, the FDA and the Centers for Disease Control and Prevention said in a joint statement.
“We are ready for booster doses when the science shows they are needed,” the agencies said.
The delta version, which was first identified in India, is believed to be about 60 percent more contagious than the alpha, the version of the virus that spread to the UK and much of Europe earlier this year , and was probably twice as contagious as the original coronavirus.
The delta variant is now causing outbreaks among illiterate populations in countries such as Malaysia, Portugal, Indonesia and Australia. Delta is also Major version now in USA, the CDC reported this week.
Until recently, infections in the United States had reached their lowest level since the start of the pandemic. Hospitalizations and virus-related deaths continue to decline, but new infections may rise.
It is not yet clear to what extent the variant is responsible; A slow vaccination campaign and rapid reopening are also playing a role.
Citing data from Israel, Pfizer and BioNTech suggested the efficacy of their vaccines “in preventing both infection and symptomatic disease declined six months after vaccination.” Given the rise of Delta and other variants, the companies stated that “a third dose may be needed within 6 to 12 months after full vaccination.”
Health officials in Israel have estimated that complete vaccination with Pfizer-BioNTech provides only 64 percent efficacy against the delta variant. (Efficacy against the original virus is over 90 percent.)
But Israel’s guess Many other studies have been refuted Finding out that the vaccine is highly effective in preventing infection – against all types. A recent study showed, for example, that mRNA vaccines like Pfizer trigger a persistent immune response in the body that may protect against coronavirus for years.
“Pfizer looks opportunistic by hanging a declaration behind too early and inappropriate data from Israel,” said John Moore, a virologist at Weill Cornell Medicine in New York. “It’s not theirs to decide when the time is right to use a booster here.”
The companies described their plan to develop a new vaccine against Delta as a sort of backup effort in case the original vaccine’s boosters fail. The new vaccine will target the entire spike protein, as opposed to a single part, and the first batch has already been produced.
The delta version poses challenges to the immune system. In the journal Nature, French researchers reported new evidence Thursday that the delta variant May partially bypass the body’s immune response Changes in the spike protein on its surface make it more difficult for the antibody to attack.
After receiving the first and second doses of vaccines, the team analyzed blood samples from 59 people. Blood samples from only 10 percent of people immunized with a single dose of the AstraZeneca or Pfizer-BioNTech vaccines were able to neutralize the delta and beta variants in laboratory experiments.
“A single dose of Pfizer or AstraZeneca was either poor or not efficient at all against beta and delta variants,” the researchers concluded. Data from Israel and the UK broadly support this finding, although those studies also suggested that a single dose of the vaccine was still sufficient to prevent hospitalization or death from the virus.
But the second dose increased the efficacy to 95 percent.. There was no major difference in the levels of antibodies elicited by the two vaccines.
“If you receive two doses of an mRNA vaccine, you are very well protected against serious illness, hospitalization and death in any regard,” Dr. Gounder said.
The researchers also looked at blood samples from 103 people who were infected with the coronavirus. delta The study found that this group was much less sensitive than alpha to samples from unrelated people.
A single dose of the vaccine significantly increased susceptibility, suggesting that people who have recovered from COVID-19 still need to be vaccinated to prevent certain types.
Taken together, the results show that the two doses of the vaccine are potently protective against all variants, as is one dose for people who have recovered from COVID-19 and have some natural immunity.
Some experts also questioned the discussion about boosters for Americans, while the world has yet to receive a single dose.
“The global situation is impossible to ignore,” said Natalie Dean, a biostatistician at Emory University in Atlanta. “It’s hard for me to imagine taking the third dose when there are frontline workers treating COVID patients who are still not vaccinated.”
Dr. Gounder said that every illiterate person provides additional opportunities to convert the virus into dangerous forms.
“If we are concerned about variants,” she said, “our best protection is to vaccinate the rest of the world, not hoarding more doses to give people in the US a third dose of mRNA vaccines.”