Tag Archives: immune responses

Breakthrough infections can lead to long COVID; genes may explain critical illness in young, healthy adults

By Nancy Lapid

(Reuters) – The following is a summary of some recent studies on COVID-19. They include research that warrants further study to corroborate the findings and that have yet to be certified by peer review.

Breakthrough infections can lead to long COVID

The persistent syndrome of COVID-19 after-effects known as long COVID can develop after “breakthrough” infections in vaccinated people, a new study shows. Researchers at Oxford University in the UK reviewed data on nearly 20,000 U.S. COVID-19 patients, half of whom had been vaccinated. Compared to unvaccinated patients, people who were fully vaccinated – and in particular those under age 60 – did have lower risks for death and serious complications such as lung failure, need for mechanical ventilation, ICU admission, life-threatening blood clots, seizures, and psychosis. “On the other hand,” the research team reported on medRxiv on Thursday ahead of peer review, “previous vaccination does not appear to protect against several previously documented outcomes of COVID-19 such as long COVID features, arrhythmia, joint pain, Type 2 diabetes, liver disease, sleep disorders, and mood and anxiety disorders.” The absence of protection from long COVID “is concerning given the high incidence and burden” of these lasting problems, they added.

Genes may explain critical COVID-19 in young, healthy adults

A gene that helps the coronavirus reproduce itself might contribute to life-threatening COVID-19 in young, otherwise healthy people, new findings suggest. French researchers studied 72 hospitalized COVID-19 patients under age 50, including 47 who were critically ill and 25 with non-critical illness, plus 22 healthy volunteers. None of the patients had any of the chronic conditions known to increase the risk for poor outcomes, such as heart disease or diabetes. Genetic analysis identified five genes that were significantly “upregulated,” or more active, in the patients with critical illness, of which the most frequent was a gene called ADAM9. As reported on Thursday in Science Translational Medicine, the researchers saw the same genetic pattern in a separate group of 154 COVID-19 patients, including 81 who were critically ill. Later, in lab experiments using human lung cells infected with the coronavirus, they found that blocking the activity of the ADAM9 gene made it harder for the virus to make copies of itself. More research is needed, they say, to confirm their findings and to determine whether it would be worthwhile to develop treatments to block ADAM9.

Pregnant women get sub-par benefit from first vaccine dose

Women who get the first dose of an mRNA COVID-19 vaccine while pregnant or breastfeeding need the second dose to bring their protective benefit up to normal, according to a new study. Researchers compared immune responses to the mRNA vaccines from Moderna Inc or Pfizer Inc and partner BioNTech SE in 84 pregnant women, 31 breastfeeding women, and 16 similarly-aged nonpregnant, non-lactating women. After the first shot, everyone developed antibodies against the coronavirus. But antibody levels were lower in women who were pregnant or breastfeeding. Other features of the immune response also lagged in the pregnant and lactating women after the first dose but “caught up” to normal after the second shot. In a report published on Thursday in Science Translational Medicine, the researchers explained that in order for a mother’s body to nurture the fetus, “substantial immunological changes occur throughout pregnancy.” The new findings suggest that pregnancy alters the immune system’s response to the vaccine. Given that pregnant women are highly vulnerable to complications from COVID-19, “there is a critical need” for them to get the second dose on schedule, the researchers said.

Coronavirus found to infect fat cells

Obesity is a known risk factor for more severe COVID-19. One likely reason may be that the virus can infect fat cells, researchers have discovered. In lab experiments and in autopsies of patients who died of COVID-19, they found the virus infects two types of cells found in fat tissue: mature fat cells, called adipocytes, and immune cells called macrophages. “Infection of fat cells led to a marked inflammatory response, consistent with the type of immune response that is seen in severe cases of COVID-19,” said Dr. Catherine Blish of Stanford University School of Medicine, whose team reported the findings on bioRxiv on Wednesday ahead of peer review. “These data suggest that infection of fat tissue and its associated inflammatory response may be one of the reasons why obese individuals do so poorly when infected with SARS-CoV-2,” she said.

(Reporting by Nancy Lapid; Editing by Bill Berkrot)

Vaccines effective vs variants despite diminished antibodies; kids may be as contagious as adults

By Nancy Lapid

(Reuters) – The following is a roundup of some of the latest scientific studies on the novel coronavirus and efforts to find treatments and vaccines for COVID-19, the illness caused by the virus.

Vaccines protect against variants despite diminished antibodies

The one-dose Johnson & Johnson COVID-19 vaccine and the two-dose vaccine from Pfizer and BioNTech appear to protect against worrisome coronavirus variants despite diminished levels of antibodies that can neutralize the newer versions of the virus, two studies in the journal Nature suggest. The authors of both studies said other immune responses may be compensating. In one study, published on Wednesday, researchers experimented with blood from people who had received the J&J vaccine two months earlier. Compared to their levels of neutralizing antibodies against the virus that was circulating early in the pandemic, levels of neutralizing antibodies against variants first identified in the UK, South Africa, Brazil and California were about three-fold lower. However, the researchers observed other “robust” immune activity and cells whose responses against the variants were undiminished. In clinical trials, the researchers noted, the J&J vaccine protected against symptomatic COVID-19 in South Africa and in Brazil, where most cases were caused by the variants. Its effectiveness in these regions raises the possibility that these other immune responses may be contributing to protection, coauthor Dr. Dan Barouch of Beth Israel-Deaconess Medical Center in Boston, said in a statement. In a separate study using blood from recipients of the Pfizer/BioNTech shots, levels of antibodies that could neutralize concerning variants first identified in India and Nigeria were lower compared to an earlier version of the virus, researchers reported on Thursday. Still, they reported “robust neutralization” of all tested variants. Neutralizing antibodies, the researchers said, do not reflect all potentially protective vaccine responses.

Children with COVID-19 may be as contagious as adults

In a community-based study of COVID-19 patients who were not hospitalized, U.S. researchers found that children and adults with symptoms had similar viral loads, which suggests children can be just as contagious as grownups. “There has been a lot of debate around school openings and about whether children could transmit the virus and we thought this study could help answer some of these questions,” said Dr. Helen Chu of the University of Washington, who coauthored a report published on Friday in JAMA Pediatrics. Her team looked at 123 children and 432 adults with COVID-19 and found that nearly all of the adults had symptoms, compared to about two-thirds of the children. “Overall, people with symptoms had higher virus levels than people without symptoms,” Chu said. “However, when you looked within these groups – those with symptoms or those without – viral load was the same whether you were a child or an adult.” She noted that swab tests were only done once, so researchers cannot be sure they took place when patients’ viral loads were highest. But overall, she said, children in the community with SARS-CoV-2 infection can have virus levels similar to adults and can transmit it to others.

Oral booster vaccine shows promise in animal tests

An experimental “booster” vaccine against COVID-19 that is taken by mouth has yielded promising early results in studies in rats, Israeli researchers said. The oral vaccine, MigVax-101, targets multiple sites on the coronavirus. Along with the spike protein on the surface of the virus, which is the target of currently available vaccines, the oral vaccine also targets two sites on the virus shell, which encapsulates its genetic material. In laboratory experiments, rats that had received two doses of vaccines that targeted the spike protein were given the oral booster. “These rats developed a much higher level of antibodies for neutralizing the disease than did control group rats that received a placebo or a third injection of the (original) vaccine,” said David Zigdon of MIGAL Galilee Research Institute Ltd, who coauthored a report posted on Wednesday on bioRxiv ahead of peer review. If it is proven safe for humans, an oral vaccine might trigger strong immune responses in the mucosal surfaces of the mouth and upper respiratory tract, which would in turn help block viral entry, the researchers speculated. An oral vaccine could be particularly useful in developing countries because it would avoid the need for distribution of needles and could be self-administered.

(Reporting by Nancy Lapid and Christine Soares; Editing by Bill Berkrot)