Health Highlights: May 27, 2021

COVID-19 Vaccines May Give Protection for Years: Studies

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.

"We think a lot of congenital abnormalities are developing quite early during this period," said Lovell-Badge, the AP reported. "By understanding these early stages better, it might allow us to adopt simple procedures to reduce the amount of suffering."

But not everyone is comfortable with the new guidelines, and some worry they could allow human embryos to be grown at more advanced stages in the lab.

Marcy Darnovsky, executive director of the Center for Genetics and Society, told the AP that it's tough to find scientific justification for the new guidelines.

"When an embryo is in a petri dish outside the body, are you going to really be able to tell anything meaningful about miscarriage or embryonic development?" she said.

Darnovsky was also worried the guidelines don't impose a limit on how long human embryos could potentially be grown.

The new guidelines do prohibit human cloning, transferring human embryos into an animal uterus and the creation of human-animal chimeras, saying such work "lacks scientific rationale or is ethically concerning."

U.S. Intelligence Told to 'Redouble' Efforts to Determine Source of COVID-19

The U.S. intelligence community been told to "redouble" their efforts to learn the origins of the COVID-19 pandemic, President Joe Biden said Wednesday.

The move was prompted by a new report questioning whether the new coronavirus originated in a lab in Wuhan, China, according to CBS News.

The intelligence community has 90 days to "collect and analyze information that could bring us closer to a definitive conclusion" about how the pandemic began, Biden said.

"As of today, the U.S. Intelligence Community has 'coalesced around two likely scenarios' but has not reached a definitive conclusion on this question," he said, CBS News reported.

"Here is their current position: 'while two elements in the IC leans toward the former scenario and one leans more toward the latter -- each with low or moderate confidence -- the majority of elements do not believe there is sufficient information to assess one to be more likely than the other.'"