(Reuters)

Older adults exposed to seasonal flu strains that circulated before 1968 may be less vulnerable to bird flu as they are likely to have antibodies that recognize and attack the H5N1 avian flu virus, researchers reported in Nature Medicine.

Younger adults and children do not have such antibodies and might benefit more from bird flu vaccines, even if the vaccines are not specifically tailored to the current strain circulating in birds and cattle, the researchers said.

Testing blood samples from 157 people born between 1927 and 2016, they found that an individual’s birth year was closely linked to the amount of H5N1-fighting antibodies in their blood.

Early childhood influenza exposures can elicit immune responses that last a lifetime, study leader Scott Hensley of the University of Pennsylvania said in a statement.

Antibody responses that were primed by the seasonal flu viruses H1N1 and H3N2 “decades ago can cross-react to H5N1 avian viruses circulating today,” Hensley said of their findings.

Most of these antibodies cannot prevent infections, but they will likely limit severity of disease if there is a bird flu pandemic, he added.

When a separate group of 100 volunteers received a vaccine designed to target an older bird flu strain that circulated in 2004, antibodies that could recognize modern bird flu strains increased slightly in older adults but “substantially” in children, the researchers reported.

In the event of a pandemic, younger individuals are therefore more likely to benefit from bird flu vaccines, even those not tailored to a current strain, they said.

The U.S. Centers for Disease Control and Prevention currently considers the risk from bird flu to the general public to be low. But scientists worry the virus could mutate in ways that will allow it to spread more easily among people.

Shorter-course radiation safe in prostate cancer

When patients need radiation therapy for localized prostate cancer, a shorter course of treatment is just as effective and safe as a longer course, as long as the same dose is administered, a new study found.

The shorter approach delivers slightly higher doses of radiation per session, allowing a total treatment duration of four to five weeks instead of seven to eight weeks, researchers reported in The Lancet Oncology.

So-called moderately hypofractionated radiotherapy (MHFRT) is already the most commonly used radiation regimen for prostate cancer, but it had not been clear whether the higher daily dose increased risks for side effects such as urinary incontinence, chronic diarrhoea and rectal bleeding.

The researchers analyzed data pooled from more than 5,800 participants in earlier trials who had received either the traditional longer course of therapy, or isodose MHFRT, which maintains the total radiation dose, or dose-escalated MHFRT, which increases the total dose in hopes of improving tumor control.

While the researchers expected better outcomes with the dose-escalated MHFRT, they saw no difference in recurrence rates after a median follow-up of 5.4 years, regardless of regimen. Side effects were more troublesome with the dose-escalated MHFRT but not when the radiation dose was the same as in the standard longer-term regimen.

“These findings reinforce isodose MHFRT as the standard of care, offering the same cancer control as conventional treatment but with fewer side effects than dose-escalated MHFRT,” study leader Dr. Amar Kishan of the UCLA Health Jonsson Comprehensive Cancer Center said in a statement.

“Less time in treatment can still mean the best possible results,” Kishan said.

An editorial published with the study notes that dose-escalated MHFRT may be advantageous when utilizing newer techniques that focus radiation directly at the tumour rather than the entire prostate.

Choosing the right blood component for specific injuries may be beneficial

Giving specific blood components to trauma patients depending on their injuries might improve their odds of survival, researchers say.

For example, giving plasma that has been separated from other parts of donated blood improves outcomes in patients with head injuries or shock, whereas giving unseparated, or whole, blood may be best for other hemorrhaging patients, the researchers reported in Cell Reports Medicine.

The researchers looked at more than 1,000 injured patients who were likely to need emergency surgery and sampled their blood at set time points. They also studied 134 injured patients who received at least one unit of a blood product – red blood cells, plasma, platelets or whole blood – before admission to the hospital.

They found that receiving a higher proportion of separated plasma before arriving at the hospital, as opposed to plasma in whole blood, was associated with improved blood clotting in patients with severe shock and signs of head injury. It also reduced post-admission transfusions in patients with head injuries.

In blood sample analyses, researchers found the plasma likely had an impact on the proteins that help with inflammation, clotting and wound repair.

It is not clear, however, why patients who received separated plasma fared better and had blood sample findings more conducive to healing, compared to patients who received the same amount of plasma but in whole blood.

Whole blood can be kept for 21 days, while plasma alone has a five-day shelf life, the researchers noted.

“Perhaps when kept in whole blood the proteins in the plasma change over time, possibly because the blood cells release enzymes that act on the plasma proteins,” study leader Dr. Jason Sperry of the University of Pittsburgh Medical Center said in a statement.

Sperry noted that it isn’t practical for ambulances to carry plasma, since it expires so quickly and must be refrigerated.

“Our findings indicate that it is worthwhile to overcome these challenges,” Sperry said.