This week's roundup of some of the latest scientific studies on the coronavirus and efforts to find treatments and vaccines for COVID-19 investigates the possible link between influenza outbreaks and the spread of the coronavirus, newly discovered proteins SARS-CoV-2 has that may be responsible for immune triggers and how other drugs can be utilized in the fight against this infectious disease.

Flu may be linked to coronavirus spread

Influenza outbreaks may be linked with the spread of COVID-19 infections, according to a European study.

The researchers created a mathematical model of transmission of the coronavirus in Belgium, Italy, Norway and Spain. It calculates that higher rates of influenza infections would be associated with increased coronavirus transmission in each of the countries, Matthieu Domenech de Celles of the Max Planck Institute for Infection Biology in Berlin told Reuters. He said the estimates, published Wednesday on the medical website medRxiv in advance of peer review, align with earlier research.

In Italy, he noted, higher rates of flu vaccination have been linked with lower rates of death from COVID-19. Also, he said, a U.S. study of nearly 11,700 people tested for COVID-19 found that those who had flu vaccines were less likely to have a positive test.

None of these studies proves that flu vaccines affect the spread of COVID-19 or an individual's risk for it, and other factors might explain the associations. Still, de Celles said, in advance of "the upcoming 'twindemic'" of seasonal flu and COVID-19 in the northern hemisphere, "our results suggest the need to increase vaccination against influenza," which may not only reduce the burden of influenza but also limit COVID-19 cases. (Here's why you should consider having a flu shot this year)

Rheumatoid arthritis drug found to aid COVID-19 recovery

Hospitalized COVID-19 patients being treated with Gilead Sciences Inc.’s antiviral medication remdesivir recovered about a day sooner, on average, if they also received Eli Lilly and Co.’s rheumatoid arthritis drug baricitinib, clinical trial investigators found.

The trial, sponsored by the U.S. National Institute of Allergy and Infectious Diseases (NIAID), included more than 1,000 patients. The study also showed that compared to patients who did not receive the arthritis drug, those who did had better outcomes at 15 days after they enrolled in the trial. Based on the data, Lilly plans to discuss the potential for emergency-use authorization with the U.S. Food and Drug Administration (FDA). The company announced the results of the so-called ACTT-2 trial in a news release Monday. The results have not been formally published yet.

Experts tell when to test for COVID-19 antibodies

COVID-19 antibody tests – so-called serology tests – are widely available, but evidence of their usefulness is limited, the Infectious Diseases Society of America said as it unveiled new guidelines published earlier this month in the journal Clinical Infectious Diseases.

Antibodies to the coronavirus do not show up in the blood for quite a while after someone becomes infected, so serology tests are unreliable for diagnosing COVID-19 unless a patient has been sick for weeks, according to the guidelines.

The panel of authors, led by Dr. Kimberly Hanson of the University of Utah, listed three instances in which a test for antibodies to the coronavirus would be warranted. The first one is when doctors strongly suspect a patient has COVID-19 but gold-standard diagnostic PCR molecular tests that look for genetic components of the virus have been negative and at least two weeks have passed since the onset of symptoms.

The second is when a child has signs and symptoms of multisystem inflammatory syndrome, a life-threatening condition that has been linked with previous coronavirus infection. The third is when public health officials conduct so-called serosurveillance studies to track the proportion of the population that has been exposed to the virus.

Newly discovered coronavirus proteins may be immune triggers

Scientists have discovered 23 previously unknown proteins made by the coronavirus, including four that might be triggering patients’ immune system to act – or in some cases, to overreact – and cause severe illness.

For the most part, proteins in this new virus have been identified based on computational predictions and similarities with other coronaviruses. But these researchers took a different approach.

By tracking protein-producing “machines” in cells called ribosomes, they were able to map exactly which parts of the genetic code of the virus were being translated into proteins, study co-leader Yaara Finkel of the Weizmann Institute of Science in Israel told Reuters. Most of the newly discovered proteins probably have regulatory functions in the virus – that is, they help keep it active – except for the four “full-fledged proteins” that might be alerting the immune system to the presence of a foreign invader, Finkel and colleagues wrote in a study published in the journal Nature on Wednesday.

More work is required to determine the roles these proteins play in infection, Finkel said, but that knowledge could "lead to a better understanding of the progression of the infection, as well as better ways of either treating COVID-19 or preventing the dangerous immune over-response."