Immune cells may recognize the coronavirus years later; Low interferon levels identify high-risk COVID-19

Researchers in Singapore are not worried that antibodies to the novel coronavirus fade quickly. 

More important, they said, is that immune system cells called T cells and B cells "remember" the virus and can trigger an immune response.

As reported on Wednesday in the journal Nature, the researchers looked for "memory" T cells in 36 COVID-19 survivors, 23 survivors of the 2003 coronavirus that caused SARS, and 37 people who never had either illness.

All COVID-19 survivors had T cells that recognized the novel coronavirus. The SARS survivors all had T cells that remembered the 2003 virus - and their T cells also recognized the new coronavirus.

Furthermore, more than half of those who were never infected with either coronavirus had protective T cells, suggesting they may have encountered other coronaviruses in the past, and there may be some pre-existing immunity to the new coronavirus in the general population.

"We find the present discussion about 'antibodies are fading away' a little pointless," three of the researchers told Reuters in a joint email.

"What is important is that a level of B and T cell memory remain to be present to quickly start an effective immune response able to stop viral spread," said Anthony Tanoto Tan of Duke-NUS Medical School, along with colleagues Nina Le Bert and Antonio Bertoletti.

T cells can kill infected cells to slow the virus down, and they also help instruct B cells to produce antibodies, the researchers said.

Low interferon levels identify high-risk COVID-19

Low blood levels of a type of interferon (IFN) could identify COVID-19 patients at high risk for severe pneumonia and acute respiratory distress syndrome.

Interferons are naturally occurring proteins that help the body's immune system fight infection.

In a study published on Wednesday in the journal Science, researchers found that severely and critically ill COVID-19 patients had severely impaired production of IFN type I, persistent virus in the blood and an excessive inflammatory response.

They said the findings support the potential value of treating these patients early on with IFN, combined with anti-inflammatory drugs or steroids such as dexamethasone in the most severely ill people.

They also found that low plasma levels of type-I IFN were seen before patients began to deteriorate and require intensive care.

"Levels of circulating Type 1 IFN could even characterize each stage of disease, with the lowest levels observed in the most severe patients," they said in a news release. -- Reuters