A new study suggests that T cells might provide individuals who had a mild or asymptomatic case of Covid-19 with lasting immunity against future infection, even if their blood contains no neutralizing antibodies.
Most people who are exposed to SARS-CoV-2, the coronavirus that causes Covid-19, only experience mild symptoms or none at all.
However, the infection can still pass from them to other people, and the overall case fatality rate appears to be converging on 0.5–1.0%.
It is, therefore, important to establish whether individuals who have contracted the virus once can contract it again and become contagious, or whether they are immune to future infection.
Their participants fell into five categories:
• people with ongoing moderate or severe Covid-19
• individuals convalescing after a mild or severe infection
• asymptomatic family members exposed to the infection
• healthy individuals who donated blood during the pandemic
• healthy individuals who donated blood in 2019, before the pandemic
IS COVID-19 MORE DANGEROUS BECAUSE SARS-COV-2 REDUCES SPECIFIC MICRORNAS?
A team of researchers proposes that the SARS-CoV-2 virus acts as a microRNA “sponge” to reduce microRNA levels in ways that assist viral replication and block the host immune response.
Coronaviruses (CoVs) are single-stranded RNA viruses that experts originally considered to be relatively mild. They include the viruses that cause the common cold.
However, researchers have stopped thinking of these viruses as mild after the outbreaks of severe acute respiratory coronavirus (SARS-CoV) in 2002, Middle East respiratory syndrome (MERS-CoV) in 2012, and the current global COVID-19 pandemic, for which the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible. Currently, there is no vaccine available for SARS-CoV-2. Research has focused on understanding virus pathogenicity and, importantly, on restoring and enhancing patients’ immunity. Researchers are now considering innovative approaches, such as the use of human microRNAs (miRNAs). Our immune systems are primed to fight off viruses. As evidence about how our bodies react to SARS-CoV-2 emerges, we look at how different immune cells work together to fend off the new coronavirus.
