COVID: Earlier detection; reinfection in young

Detecting severe COVID-19 earlier

There is some very good news to report in the battle against COVID-19 as researchers may have discovered a way to detect early those who will become severely ill. Most people who are infected with SARS-CoV-2 develop no or only mild symptoms. However, some individuals suffer severe life-threatening cases of COVID-19 and require intensive medical care and a ventilator to help them breathe. Many of these patients eventually succumb to the disease or suffer significant long-term health consequences. To identify and treat these individuals at an early stage, a kind of “measuring stick” is needed. So, there has been intense interest in identifying predictive biomarkers that can recognize those who are at risk of developing severe COVID-19.

A team led by Professor Burkhard Becher at the Institute of Experimental Immunology at the University of Zurich, working with researchers from France, has now discovered such a biomarker. It appears to be the number of natural killer T cells in the blood. These cells are a type of white blood cell and part of the early immune response.

“The number of natural killer T cells in the blood can be used to predict severe cases of COVID-19 with a high degree of certainty, even on a patient’s first day in a hospital,” says Burkhard Becher.

The researchers are hoping that these new findings also will make it possible to investigate new therapies against COVID-19. The rapid deterioration in the health of COVID-19 patients is caused by an overreaction of the body’s immune system. A closer look at this process may lead to important new lifesaving therapies.

Past infection does not fully protect young people against reinfection

Although antibodies induced by COVID-19 infection are largely protective, they do not completely protect against reinfection in young people. A new longitudinal, prospective study of more than 3,000 young, healthy members of the U.S. Marines Corps conducted by researchers at the Icahn School of Medicine at Mount Sinai and the Naval Medical Research Center, has turned up some interesting clues.

“Our findings indicate that reinfection by SARS-CoV-2 in healthy young adults is common,” said senior study author Dr. Stuart Sealfon, who is a Professor of Neurology at the Icahn School of Medicine at Mount Sinai. “Despite a prior COVID-19 infection, young people can catch the virus again and may still transmit it to others. This is an important point to know and remember as vaccine rollouts continue. Young people should get the vaccine whenever possible, since vaccination is necessary to boost immune responses, prevent reinfection and reduce transmission.”

The study was conducted between May and November 2020 and it revealed that around 10% (19 out of 189) of participants who were previously infected with SARS-CoV-s became reinfected, compared with new infections in 50% (1.079 out of 2,247) of participants who had not been previously infected.

The study population consisted of 3,249 predominantly male, 18 to 20-year-old Marine recruits who, upon arrival at a Marine-supervised two-week quarantine prior to entering basic training, were assessed for COVID-19. Recruits who tested positive for a new second COVID-19 infection during the study were isolated and the study team followed up with additional testing. The researchers found participants who became reinfected had lower antibody levels against the SARS-CoV-2 virus than those who did not become reinfected.

The authors found the amount of measurable SARS-CoV-2 virus in reinfected recruits was on average only 10 times lower than in infected seronegative participants, which could mean that some reinfected individuals could still have a capacity to transmit infection. The authors note that this will need further investigation.

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