COVID-19 vaccines may provide protection for at least a year, and possibly even a lifetime to people who were previously exposed to the virus, two new studies suggest.
Both of them looked at people who had been exposed to the coronavirus (SARS-CoV-2) that causes COVID-19 about a year earlier, The New York Times reported.
Cells that remember the virus persist in the bone marrow and may produce antibodies whenever needed, according to a study published in the journal Nature.
The other study found that these memory B cells continue maturing and strengthening for at least 12 months after initial infection with the coronavirus. It was posted online at the biology research site BioRxiv.
Together, the findings suggest that most people who've recovered from SARS-CoV-2 infection and were later vaccinated will not require booster shots, the Times said.
But it's likely that vaccinated people who were never infected will still need booster shots, as well as some people who were infected but did not produce a strong immune response against the virus.
"The papers are consistent with the growing body of literature that suggests that immunity elicited by infection and vaccination for SARS-CoV-2 appears to be long-lived," Scott Hensley, an immunologist at the University of Pennsylvania who was not involved in the research, told the Times.
The memory B cells that are produced in response to coronavirus infection and boosted by vaccines are so powerful that they can fight off even variants of the virus, eliminating the need for boosters, according to Michel Nussenzweig, an immunologist at Rockefeller University in New York who led one of the studies.
"People who were infected and get vaccinated really have a terrific response, a terrific set of antibodies, because they continue to evolve their antibodies," Nussenzweig told the Times. "I expect that they will last for a long time."
Scientists Say They've Found Cause of Rare Blood Clots Linked to Some COVID Vaccines
The cause of rare blood clots in some people who've received the AstraZeneca and Johnson & Johnson COVID-19 vaccines has been found, researchers report.
The vaccines use adenovirus vectors (common cold viruses) to transfer the vaccine's components into cells, but some of the material slips into the nucleus of cells, which isn't an ideal location for the virus to make proteins, the German scientists explained, the Washington Post reported.
These inferior proteins, some of which may split apart inside the body, could trigger blood clots in a small number of people who receive the vaccines, according to the non-peer-reviewed study posted online.
Russia's Sputnik V coronavirus vaccine also uses an adenovirus vector, the Post reported.
COVID-19 vaccines that use mRNA technology, including Pfizer and Moderna, work in a different way and "should represent safe products," the study said.
Rolf Marschalek, one of the study's authors, told the Financial Times that adenovirus vector vaccines can be tweaked to eliminate the risk of blood clots, and said that Johnson & Johnson "is trying to optimize its vaccine now," the Post reported.
Restrictions Eased on Use of Embryos in Research
An international standard that limits how long human embryos can be grown in a laboratory has been extended under limited conditions, which will remove a barrier to stem cell research.
But the International Society for Stem Cell Research didn't specify how much longer embryos could be grown beyond the 14-day limit specified in 2016 guidelines, the Associated Press reported.
That restriction has blocked research of a crucial period in embryo development, typically between 14 and 28 days, according to Robin Lovell-Badge, a stem cell expert at the Crick Institute in London and chair of the group that wrote the new guidelines.
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