MasterofDope έγραψε: 25 Μάιος 2021, 00:39
Protection lasts for at least 6 months, likely longer
Separately, Pfizer-BioNTech said that the ongoing phase 3 clinical trial of its mRNA vaccine shows that strong immunization persists for at least 6 months among vaccinated individuals.
Researchers found that the vaccine was 100 percent effective against severe disease as defined by the CDC, and 95.3 percent effective against severe COVID-19 as defined by the Food and Drug Administration (FDA).
The vaccine was also found to be 100 percent effective against one of the main COVID-19 variants (known as B.1.351) currently circulating widely in South Africa.
A study that included 12,000 vaccinated individuals also found “no serious safety concerns” with the Pfizer-BioNTech vaccine, the companies announced.
“The good news is that in the 6-month status report from Pfizer, immunity stays very strong, and we anticipate that it will continue to stay strong,” said Bailey.
“These people [in the study] have had the vaccine the longest, and it tells us it lasts at least 6 months,” added Bailey. “But it’s definitely longer than that — it’s not just going to drop off after 6 months. I would have been concerned if efficacy had dropped by a third or half.”
The fact that COVID-19 vaccine effectiveness remained almost unchanged over the span of the study period is an indication that protection will be enduring.
Bailey noted that some vaccines, such as those for measles, mumps, and rubella, generally confer lifetime immunity. Others, such as the flu vaccine, require a new shot every year.
“We don’t know which camp the COVID-19 vaccine will fall into,” she said. “If we do need a booster shot for COVID-19, we do know that it will be easy to produce” thanks to the new mRNA technology, she added.
Bailey said that the vaccines now in use appear to be effective against the COVID-19 variants circulating in the United States. But as the coronavirus continues to mutate, variants could emerge that are more resistant.
“My prediction is that a situation in which we would need to have a booster shot in the future is not because the first dose of vaccine faded but because there is a new variant that might emerge,” she said.